Bird Traffic casualties and road quality for breeding birds
a summary of existing papers with a bibliography.
by Johannes Erritzoe
© Johannes Erritzoe 2002
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Content:
Introduction.
What makes roads so attractive to many birds?
The negative impact of roads for the bird community.
Methods used.
Sources of error.
The quality of habitats along roads as breeding sites.
The importance of habitats along roads for the road
kills.
Highways versus other roads.
The difference in numbers of traffic casualties between
areas.
What is the importance of speed for the number of road-killed
birds?
Does traffic density effect the number of road-killed birds?
How much has the density of traffic increased?
Does the behaviour of different bird species influence
the number of road kills?
Why do many birds fail to estimate the speed of a car?
Crepuscular and nocturnal birds.
Irruptive species.
Scavengers.
Are there species whose decline may be caused by traffic?
Is it possible to monitor a population in a given area
by means of the number of traffic accidents?
In which months are the birds killed by traffic?
How much influence has the weather on road kills?
Other causes of traffic casualties.
At which time of the day and on which day of the week are
most birds road killed?
The percentage of road-killed young birds versus adult
birds?
Are traffic casualties lean, normal or fat?
Overview of the calculated total number of road-killed
birds or animals/year in different countries.
Which species are most commonly road-killed in Europe?
Most commonly killed species in other continents.
Traffic killed House Sparrows and Tree Sparrows calculated
as per cent compared with all other traffic killed species
Has traffic killing any influence on the bird populations?
Proposed measures against traffic kills.
Discussion.
Acknowledgement
Bibliography.
Recommended Citation.
Tables:
1: Which sex is more often killed?
2: Which age-group is more often killed?
3: The ten most common traffic victim species in Europe
4: The ten most often killed birds in the USA
5: House and Tree Sparrow traffic killed per month.
6: Bird kills calculated according to the average number
of km between each carcase.
Introduction
Conducting
a study of traffic accident among birds in South Jutland, Denmark, I got the
idea of undertaking a survey of all previous works upon this theme to gain
new inspiration for profitable research. The result was astonishingly good,
and as there has never before been produced an all- round review (traffic
casualties are not included in the Zoological Record), this may be of some
interest and - I hope - result in new research and future insight into this
serious man-made problem. Birds are only a part of the total road death toll;
mammals, reptiles and amphibians make up together maybe a still greater proportion,
but to include these too would be a formidable task more suitable for a book,
and because the problems are quite different for birds compared with those
of non-flying animals, this separation may be defensible. In the following
the most interesting results from ornithological articles from the whole world
are presented. At the end there is a bibliography which also includes papers
not cited in this account.
Already in 1926 in America Alden H. Hadley wrote: “It is perhaps, too much to state as yet that motor vehicles, at present constitute a menace of major importance to birds and animals, but at least they must be included among those agencies of modern civilization which in the long run are highly detrimental to wild life”. Was his prophecy right or has evolution solved that problem?
The first time a report of animal traffic casualties was published that I know about was in the year 1925 (Stoner) in America, and here the interest in the case was so great that by 1940 an additional 52 papers had been printed, all presenting the results of counting carcasses on the road, usually from a car, narrative and without any analysis of the results. In Europe the interest awoke only slowly. Not till 1927 a little paper was published in England, in Germany in 1937 and two years later another one in England, but only in the fifties did it become a common theme in ornithological periodicals. The first thorough pioneer research was carried out by a Dane, Linhard Hansen, who during three periods, 1957-58, 1964-65 and 1980-81, travelled 23.299 km on a moped and counted all the animals found. The new aspects were that he did it all the year round on the same three sorts of roads: secondary roads, main roads and highways. From this material it was possible for the first time to form a rough estimate of the total number of road-killed animals in a country.
Inspired by Hansen’s work, a Swedish team, Göransson et al., carried out a similar study but collected more data, e. g. the various types of roadside cover and their influence upon bird casualty numbers. Later followed many other important works, of which I will here only emphasize Jesper Bruun-Schmidt’s paper ‘Trafikdræbte dyr’ from 1994, where also the quality of habitats along roads was taken into consideration, but also many other parameters like the influence of the weather, age and sex composition, etc.
What makes roads so attractive to many birds?
Roads
work as ecological traps (Dhindsa et al. 1988) or, as many authors
state, as emergency hunting grounds. Highways should be considered as separate
ecological systems with a character of their own as specific barriers which
separate habitats of varied plant and animal communities (Nankinov & Todorov
1983). Roads have an ’edge effect’, because they are experienced as the end
of a habitat, and there is a tendency for many animals to have a larger population
near the border of the habitat (Dhindsa et al. 1988). Roads break the
uniformity of the farmland and offer a greater variety of food than can be
found in the fields, e. g. garbage that has been thrown into the roads by
car drivers (Dill 1926) or spilt grain after havest (Bräutigam 1978, Slater
1994). In the winter of 1982 a highway with central reserve in France was examined for voles. There were 250-400 voles per ha along the road (Bourquin
1983). The road alsoserves as a larder for scavengers, (Borrmann 1969). Many
stakes and fencing posts along roads give birds of prey fine observation posts
and from these they can rush on prey without a great energy consumption (Robertson
1930, Bourquin 1983). In moist weather there should be more earthworms because
these come up to the surface due to vibration on the road (Tabor 1974), for,
e. g. Rooks Corvus frugilegus to eat, and Song Thrushes Turdus
philomelos use the road as an anvil to smash their snails, and many birds
like sparrows drink from and bathe in puddles along the road (Hodson 1962).
Because of the heat on the road many insects arrive which swallows and Swifts
Apus apus make use of, but also wagtails and Skylarks Alauda arvensis
forage on insects here, most of all, maybe, because they are much easier to
find (Bergmann 1974). After heavy rain numerous insects are washed onto roads
or driven out of the ground (Zumeta & Holmes 1978).
It can be fatal for insectivorous birds in northern regions when bad weather starts in early spring, and in such situations many early arriving forest birds are forced to forage on roads (Zumeta & Holmes 1978), and in winter these are the first places cleared of snow (Lindsdale 1929). Salt on roads used for de-icing in wintertime attracts crossbills in great numbers (Meade 1942, Oeser 1977).
The high concentration of breeding birds along roads can perhaps be explained by the rare occurrence of their enemies there [?] (Nankinov & Todorov 1983). May be mud for swallows’ nest building should maybe also be mentioned (Finnis 1960). The telephone and power pole lines are conspicuous features along most roads used as observations posts and should be considered as part of the road system. Birds also collect grit for their gizzards on roads (Meinertzhagen 1954).
Like stones, road surfaces have the property that they can absorb and keep large quantities of sun heat. The average temperature on the road surface is 6.7 o higher than the air in shade. The greatest number of birds on the roads in America was seen when the road surface was 7-10o warmer than the surroundings (road temperature 26-34o and the air 19-26o). The lower critical temperature for thermoregulation in many passerines is 22-23o, however, for the Common House Sparrow Passer domesticus it has been documented by laboratory test that it is most active at 22o. (Whitford 1985). In Wisconsin, USA, the road temperature is in July and August 22o seven hours longer in the daytime than the surroundings. Birds which use this heat energy save many calories that they would otherwise have to use to maintain their body temperature. A warm and wet road has more birds than a warm and dry one, but the number falls when the wind increases (Whitford 1985).
The negative impact of roads for the bird community
The
environmental impact of the road-traffic complex is greater than usually suspected.
The discharge of substances such as gases, oil. poison and other liquids,
salt and waste may lead to the pollution of air, soil and water and effect
the population of both plants and animals throughout a large area (Zande et
al. 1980). But also the noise from the vehicles is a stress factor. Thus
a study in open grassland areas in the Netherlands showed that shorebirds
like Lapwings Vanellus vanellus and Black-tailed Godwits Limosa
limosa were sensitive to disturbance over surprisingly long distances,
ranging from 5-600m for a quiet rural road to 16-1800m for a busy highway
(Zande et al. 1980). Roads can work like traps. After rain the road
may look like a water surface, which can explain why water birds can occasionally
be found as traffic casualties (Short & Craigie 1958, Haas 1964). But
first of all, the many millions of road killed birds each year is a serious
problem. This work, however, does not treat all the problems in connection
with pollution.
Methods used
There
are great differences among the methods used in the many published accounts,
which makes a comparison of them difficult. Most papers state only how many
dead birds were found on a trip in some vehicle, where date and route are
given (e.g. White 1927, 1929, 1933, Beckmann 1961, Haas 1964, Blumel &
Blumel 1980). Other counts were made by moped, bicycle or on foot (e. g. Barnes
1936, Günther 1979, Hansen 1982, Seibert & Conover 1991). In Sweden the
roads were inspected by car at ‘normal speed’ and the car was stopped only
when it was necessary to identify a bird. On the most thoroughly examined
route the road was inspected at least once every day, but most often both
mornings and evenings from 7-10 and 15-18. Date and site where the road killed
bird was found was recorded and the exact place marked on a map 1: 50.000.
For some sex and age were also registered (Göransson et al. 1978).
Dunthorn & Errington (1964) ringed a great number of young birds from nests directly in connection with the road in order to study mortality. Stewart’s (1971) study noted how many road killed birds were found. The width of the road was measured, and the road was divided into middle, side and ditch to describe exactly where each bird was found. Hansen (1982) rode along different routes on dissimilar road types on a moped every week. In the Netherlands a population of Willow Warblers Phylloscopus trochilus in a 154 ha willow tree habitat was studied both near the highway with 45,000 vehicles passing every day and in the adjoining countryside to compare the condition of the birds. (Reijnen & Foppen 1991, Foppen & Reijnen 1994).
In India on four roads, each of 1km length, a trip was made on all ”bright” days between 12 and 18 o’clock at 50-60km/h, counting all live birds on the roads. During the same study period seven line transects were made at some distance from the road to compare the species diversity with that found on the road (Dhindsa et al. 1988).
In a Spanish study of the Little Owl Athene noctua, a 40km route was gone over by two persons at night, dawn or dusk in a car at 40-50km/h, and the ‘navigator’ used an intensifier to find the owls. All cars coming from the opposite direction were counted, the owls’ foraging height, time, kind of perch, perch posture and habitat were recorded (Hermandez 1988).
Sources of error
Cats
Felis domesticus, Foxes Vulpes vulpes, Stoats Mustela erminea,
Weasels Mustela nivalis, Hedgehogs Erinaceus europaeus, Rats
Rattus norvegicus and small rodents, but also gulls, Ravens Corvus
corax, Magpies Pica pica, crows and many owls take many road killed
birds (Göransson et al. 1978, Blümel & Blümel 1980). Bergmann (1974)
found a traffic killed Hedgehog with a Robin Erithacus rubecula in
its mouth. Cats are the most common nocturnal scavengers both in town and
country, and the Carrion Crow Corvus corone can fly away with carrion
up to approx. 150g (Slater 1994). Road cleaners remove many of the larger
birds (Hodson & Snow 1965). Birds which can be eaten are taken by people,
or the birds are caught on the radiators of cars (Bruun-Schmidt 1994).
Many works have studied the sources of error caused by scavengers, e. g. 42 dead birds were placed on the road, most of them already removed in the late afternoon, about dusk or early next morning (Hodson 1966, Johnson 1989). In another study the average time before a bird was gone was 48 hours (Vignes 1984). In one more work with 53 bird carcasses, 73% of small birds were removed after 32 hours, 17% after 12 hours and 56% of the larger birds already after 5 hours. However, those placed outside the paving were not all gone until after 14 days (Göransson et al. 1978:92).
Many birds are not killed at once and manage to fly some metres into scrub before they die, or they are thrown away from the road by the speed wind from other cars. Göransson et al. (1978) found some animals which had dragged themselves into the surrounding vegetation merely by watching carrion-eating birds like Hooded Crows Corvus conone cornix and Rooks. Haas (1964) tried to find several birds which had collided with his car, but without success
But not only scavengers are a great source of error, the speed with which vehicles totally wear out a carcass on the road is also astonishing: 50 dead sparrows were placed on a heavy traffic highway. After 90 minutes only remains of five were still to be recognized, and 30 minutes later these were also gone. The author also placed 20 sparrows on the roadside in the cut vegetation and the last was not gone till after 16 days (Stewart 1971). On another highway with 9,000 vehicles every day and night small birds were gone after 1.2 days ±0,4 and larger birds after 2.1 ±0,7 (Korhonen & Nurminen 1987). Bruun-Schmidt (1994) in Denmark came to nearly the same result: 50% of small birds gone after 9 hours, average 1.2 days, and larger birds 2.1 days. On average a road kill could be identified for 2.2 days (McClure 1951), 4 days (Scott 1938), and in cool weather even longer (Simmons 1938, Seibert & Conover 1991).
Most studies have been carried out from a car, where many birds are bound to be overlooked, especially the smaller ones. Therefore, these works record a disproportionate number of larger birds (Korhonen & Nurminen 1987). Going in a vehicle, it is often possible to check only one side of the highway (Haas 1964). In order to ascertain the error percentage a road in Sweden was checked every second hour for 25 days and nights. The result was that only about 1/3 of the small birds was found by the normal inspections, against which, birds of the size of a thrush or larger were registered in about ½ of all cases (Göransson et al. 1978:34-35). In an English report in which 76 ornithological researchers participated for a whole year, and 5,269 road kills were found, the following result was published: 12 ornithologists carried out the search by walking and found on average of 30.33 birds per mile in a year. 35 used a bicycle and got an average of 23.90 birds, 18 used a car, and their average was 10.92, or about one third of that of the walking participants. Four used a moped and got an average near that of bicycles: 22.68. The rest used a bus or partly bicycle partly moped (Hodson & Snow 1965). Hansen (1982) used a moped and tried to double-check his findings, which demonstrated that he had overlooked about 10%. Havlin (1987) spotted only 1% from a car on highways compared with the result when walking, and Haas (1964) found only 26% by car compared with bicycle. Other sorts of errors may also be mentioned here. From the early years there is a suspicion of small boys with .22 rifles, slingshots and air guns as an extra hazard (Robertson 1930, Davis 1930, Lincoln 1931). Bad light like low sun ahead also means overlooked birds (Hansen 1982).
From the above it is obvious that all published traffic accident studies are encumbered with great uncertainty, due first of all to scavengers and to cars wearing out on birds on the road, but also the way the study is made, by car, moped, bicycle or by walking makes a great difference to the result.
Results
The quality of habitats along roads as breeding sites
As
a rule the more cultivated an area is, the more roads will there be, and the
fewer different birds species will live there (Linsdale 1929). In England
roadsides are mostly cultivated grasslands, but nevertheless they form the
breeding habitat for 40 breeding species (Slater 1994). Several studies have
shown that the forest population density is lower along roads than in areas
away from roads (Ferris 1979, Räty 1979, Adam & Geis 1981, Reijnen &
Thissen 1987, Reijnen et al. 1995). However, the density of a population
is not always a reliable indication of the quality of the area (Reijnen &
Foppen 1995). Passerines breeding in hedges have less breeding success due
to predation, this applies particularly to forest species like Blackbird Turdus
merula and Song Thrush, wheréas a bird like Yellowhammer Emberiza citrinella
has more success because it breeds more in the open (Barkow et al.
2001). European Robins breeding in hedges along roads have low breeding success
because of frequent disturbances, greater predation and less food supply.
However, surprisingly the Cuckoo Cuculus canorus was the greatest disturber
of all during the brooding period! The disturbance made by humans from engines,
pedestrians and cyclists had little importance because it was always only
for a short period. Out of 21 Robin nests along roads 19 were predated (Grajetzki
1991, 1992). Gassmann and Glück (1993) pointed out that the width and structure
of the hedge influenced breeding success. The Great Tit Parus major
has less loss of eggs and nestlings and greater body mass in the wild than
in areas along roads (Bairlein & Sonntag 19 94). The method used for all
the cited works was to count the number of feeding visits of the parents.
An American study has shown that for House Finches Carpodacus mexicanus
the quantity of food brought at each visit was similar and therefore this
method should be workable [!] (Nolan et al. 2001). In Holland the Willow
Warbler was studied using colour rings. The area was 154ha with Willow Trees
and it was crossed by a highway carrying 45.000 vehicles per day. The result
was very interesting, because all Willow Warblers breeding near the road were
young birds that all had poor breeding results, and the next year they all
moved to territories further away from the road (Reijnen & Foppen 1991,
Foppen & Reijnen 1994).
Burrowing Owls Athene cunicularia nest and forage often near roadsides
in burrows made of Prairie Dogs. A study in the Rocky Mountain, Colorado gave
the result that with a traffic of 0-16 vehicles/15 min the disturbance had
little impact on nestling Burrowing Owl behaviour, and it had no impact on
productivity even though nesting locations placed them in close proximity
(Plumpton & Lutz 1993).
The importance of habitats along roads for the road kills
If
the road is higher than the surroundings, the crossing birds will fly low,
and more are killed than on roads where the surroundings are higher and where
fewer road kills occur (Wascher et al. 1988), but, by contrast, Bruun-Schmidt
(1994:37) states that most dead birds are found where the road is level with
the surroundings. Where the road runs through forests, wood edges and other
marked changes to another vegetation, wet areas, in outskirts, and stretches
with hedges on both road sides, there are many traffic casualties (Göransson
et al. 1978).,Wascher et al. 1988, Bosch 1989, Johnson 1989)
, e. g. was in Spandau, Berlin, on a 4.7km long forest stretch 1380 road killed
birdswere found between 1978 and 1988, i. e. on average 138 each year (Miech
1988), and in a four year German study 181 birds were found on a 400m long
forest road, compared with 198 birds on a 3,000m road through farmland and
meadow (Bräutigam 1978). In a Swedish study the traffic death toll was greatest
near farms and large gardens and in a valley with deciduous trees on both
sides (Göransson et al. 1978: 55). Most ‘black spots’ are found where
there are gaps and openings for birds attempting to fly from one side of the
road to the other (Hodson 1960, 1962, Dunthorn & Errington 1964, 1971).
Several authors have found the greatest number of live birds and traffic accidents
at traffic centres, maybe because these areas are more spacious, with more
vegetation than the normal highway (Hodson 1962, Günther 1979, Havlín 1987,
Bruun-Schmidt 1994). Many birds are killed where the road forms a curve, even
though the cars have to slow down here (Bergmann 1974, Hermandez 1988). Most
road kills in a study in France occurred on embanked road sections (Lodgé
2000). Also small streams crossing the road are mentioned as dangerous places
for birds (Brown et al. 1986, Johnson 1989). On a road in Bulgaria
68.9% of the birds were killed by cars going downhill because the latter could
move faster there (Nankinov & Todorov 1983).
A study in Tasmania demonstrated that there were more owl casualties on the higher part of a highway (Taylor & Mooney 1991), which tallies with a Danish study, in which were more than half of all killed owls were found on a short stretch of the highway near Skovby, the highest point of the whole examined part of the highway (Erritzoe 1999).
In another Danish study most birds were found in a little village, Kolind, compared with those found on secondary and main roads in the countryside (Bruun-Schmidt 1994: 35). The most numerous road kills occur on the outskirts of towns with gardens, because the densest populations occur here (Bräutigam 1978, Smettan 1988), e. g. 23,8 birds km/year in a garden suburb near Stuttgart, compared with 19.8 birds km/year on roads in farmland (Smettan 1988). On the other hand, roads with fewer road kills are the tedious and dull ones! In France and USA there are many straight and open highways where the traffic flows more smoothly, and here there are fewer traffic casualties (Finnis 1960).
Highways versus other roads
In
Czechoslovakia fewer perching birds were killed on highways: 0.01 per 100km
relative to other roads 0.12 (Holisova & Obrtel 1986). In Estonia on average
1.8 birds were found on a paved 10km road compared with 0.06 on gravel and
earth roads (Löhmus 1994). Birds on highways are thrown farther away from
the road because of the speed of the vehicles (Göransson et al. 1978).
It is estimated that on German highways on average one bird per day for every
5km is killed in July and August (Haas 1964). In Denmark the peak for traffic
accidents on seconddary and main roads is June to August, but for highways
February to April and July to September (Bruun-Schmidt 1994).
The difference in numbers of traffic casualties between areas.
In
Nebraska the yearly average of traffic killed
vertebrates per 100 miles was 9.1, in Iowa 42.9, in New England 70.5, and based on a small number 250 in Wisconsin
(McClure 1951). Dickerson (1939) recorded the number of animals killed west
of Mississippi as three times as large as east of the river, and Russell (1938)
reached the same result: on a 3.532km long journey he counted 1,328 casualties
west of the Mississippi and 867 east of the river. However, when the kilometres driven were taken into account, he found one bird for every 4.3km east of the
river and a bird for every 9.5km west of the river. Few casualties were found
in New Jersey and eastern Pennsylvania, but in western Pennsylvania and especially Ohio and Indiana the number increased (Hadley 1926). In Czechoslovakia on three different highways
in different directions from Brno, on the oldest and almost completely stabilized
one 14.7 birds were found for every 100km, on another later finished 16.3,
and a newly completed section 28.8, suggesting that new motorways have the
highest percentage of traffic casualties (Havlín 1987), which is also stated
by Ward (1934). Near Hessen, Germany, on roads
in farmland Bergmann (1974) found 6.5 birds per km/year, in another area with
much vegetation and fruit trees 19.6 km/year, but in Ortsbereich Marburg only
1.8 km/year, in all three cases at about the same traffic intensity. Also
other authors have noted the same great differences. On a road through farmland
in Mecklenburg, Germany, only 7.4 birds were found per km/year (Lüpke 1970),
but on a 5km road in Sachsen, Germany, which runs through villages, fields,
meadows, forest and lakes, the number was more than double: 16.5 birds per
km/year (Bräutigam 1978).
What is the importance of speed for the number of road killed birds?
The
speed of traffic has an important influence upon bird road accidents (e. g.
Hodson 1960, Dunthorn & Errington 1964, Hansen 1969, Smettan 1988). At
a speed of 35 miles (56km) the road kills start (Dickerson 1939). In Nebraska the traffic killed Pheasants Phasianus colchicus are significantly correlated
with the average speed of cars (Case 1978). In Punjab, India ‘formerly’ few birds were road-killed because few cars could exceed 80km/h.
In March-April 1985 a road (270km) was travelled both ways, one way the speed
was more than 100km/h, and 11 birds collided with the car, however, only when
the speed was over 100km/h, whereas on the return trip only 80km/h was driven
and no birds were killed (Dhindsa et al. 1988). In Germany the speed
of the traffic is a very important factor, but at a speed of below 40km/h
collisions are rare (Wascher et al. 1988), however, even lower speed
can be fatal: a car was hit by a Song Thrush at 20 miles/h (32km), and the
bird was immediately killed (Govett 1960). In 1919 paved roads were the exception
in America, and there were many miles of barely improved roads. Therefore, the speed of
vehicles was much slower, and dead birds on the road were relatively few (Jones
1927). On earth roads in farmland no road killed bird was found and on smaller
roads with less than 100 cars/day and 30-50km/h only 2 birds per km/year were
traffic killed (Smettan 1988). However, exhausted birds on migration make
an exception: On a rainforest jeep-track in Thailand Filip Verbelen (1993)
found 25-30 Hooded Pittas Pitta sordida hopping around on the track,
most of them so tired that it was possible to approach them to within 5-6m,
eight dead pittas were also found, all very lean, traffic victims in spite
of the very few cars using the track.
In a study of Little Owl in Spain 74.4% of the road-death victims were found on roads with many curves and therefore killed at a rather low speed (Hernandez 1988). German owls were 21 times more frequently killed when the speed of cars was more than 80km/h (Illner 1992). However, in cities where the speed limit is mostly 50km many bird traffic casualties also occur (Bruun-Schmidt 1994: 39). Haas (1964) who travelled 46,000km on bicycle and car, found more traffic casualties on roads with high speed limits even if the traffic density was low, and Martens (1962) stated that traffic density has no importance, but the few very fast cars kill the birds.
However, it is difficult to calculate the difference of road kills on roads with high speed and density versus roads with lower speed and fewer vehicles, because the casualties on the former are worn out so fast (Fuellhaas et al. 1989). As a striking example of this the previously mentioned Stewart (1971) can be repeated. He placed 50 dead sparrows on the highway and after 90 minutes only parts of five were still there. Another snag is the difficulty of finding birds in the vegetation along the road. At high speed 5% of the birds were thrown in the ditch and at low speed only 0.5% (Nankinov & Todorov 1983). High speed also makes the turbulence stronger, which will throw a small bird over to an oncoming car (Göransson et al. 1978: 84).
Does traffic density effect the number of road killed birds?
The
density of traffic has an important influence upon bird road accidents (Hodson
1960, Dunthorn & Errington 1964, Hansen 1969, Smettan 1988, Washer et
al. 1988, Lodé 2000). In Finland traffic density is at its peak between
June and August with an average of 10,700 vehicles/day on a certain roads.
There was most traffic and accidents on Mondays and less on Wednesdays, which
the authors suggest that the number of cars may have some importance (Korhonen
& Nurminen 1987). Hansen (1969) supported this. On small secondary roads
he found 0.10 bird/km per day, on larger secondary roads 0.24, on main roads
0.79 and on highways 3.16. In a study 14 years later the same author found,
however, that the number of road-killed animals had not risen despite more
cars on the roads, but a reasonable explanation of this could be that in the
meantime the bird populations had decreased (Hansen 1982). Another Danish
study conducted from a car showed that on a 10km secondary road with 332 vehicles/day
and night 43 birds were killed in a year, and on a 10km main road with 2823
vehicles/ day and night 96 birds were killed in a year, both roads situated
in towns (Bruun-Schmidt 1994:38,56-57). A German research carried out on foot
did not support this result: On a secondary road with 780 vehicles/ 24 h 320
road casualties were found in a year and on a main road with 2650 vehicles/24h
only 154 birds were found (Fuellhaas et al. 1989). Odzuck (1975) noted
that smaller roads present a greater danger to birds, because the birds here
are not familiar with traffic, while roads with more denser traffic give birds
’Lehrneffect’, learning effect. Martens (1962), Bergman (1974) and Case (1978)
arrived at the same result, birds quite simply learn to cross the roads at
a greater height. On Haas’ (1964) journey through Morocco and Turkey he found
comparatively many traffic casualties in spite of the less dense traffic there.
The increase in the number of cars in France and Germany does not influence
the number of owl and bird of prey traffic casualties, but the 3-4 year cycle
of mice does ((Bourquin 1983, Illner 1992).
How much has the density of the traffic increased?
In
order to provide a basis for further studies of the effect of an increased
number of vehicles on the total number of road killed birds the following
information: In America there were eighteen million vehicles in 1926 (Dill
1926) against 216 million in 1999 (US Federal Highway Administration).
In England there were in 1938 less than 2 million motorcars and in 1960 4,250,000 (Hodson 1960).
In Denmark in 1958 6.8 billion km were driven, in 1978 28.1 billion kilometres (Hansen 1982). In 1999 the number was 46 billion kilometres in cars, trucks, busses and motor bicycles (Skriver 2001), that is more than a 600% increase in 41 years.
Does the behaviour of different bird species influence the number of road kills?
Hansen
(1969) suggested that bird behaviour determines whether a species is liable
to be killed by traffic. The Blackbird has a visible peak in traffic accidents
in March, when territory and pair building takes place, which means many birds
chasing each other, and still more important, Blackbirds very often cross
a road very low above the ground (Göransson et al. 1978:88, Heinrich
1978). Birds dipping in flight over the road as they fly from hedge to hedge
often collide with vehicles (Slater 1994).
The House Sparrow is without doubt the bird most often found road killed worldwide,
cf. tables 3 and 4. Its preferred habitat is human settlements like gardens
with thick hedges and bushes, often in connection with farms. From here it
flies to the nearest cornfield on the other side of the road and often in
flocks. Every time the flock is alarmed it must cross the road to reach safety
and the risk of a collision with a vehicle is great. Sparrows forage on the
spilt corn on road sides, they sunbathe directly on the road and very often
you can see young being fed by parents there (Göransson et al. 1978:
82). Sparrows are not so shy and thus may have less reaction when a car turns
up (Heinrich 1978). Birds flying low over the ground are more exposed to collisions:
besides the already mentioned Blackbird this also applies to Song Thrushes,
Whitethroats Sylvia communis European Robins and Wrens Troglodytes
troglodytes. The Great Tit, however, is very rarely traffic-killed because
it usually crosses the road at great height (Odzuck 1975). Many birds dive
to gain speed instead of flying away from a car, or they suddenly turn around
to come back to the starting point, by which manoeuvre they lose speed. This
is often observed in Pheasants and sparrows. Maybe this behaviour has got
survival value in escaping from raptors (Govett 1960, Dunthorn & Errington
1964). In Australia the Western Rosella Platycercus icterotis typically
crosses the road and collides with an oncoming car, whereas another common
visitor on the roads, the Common Bronzewing Phaps chalcoptera is very
seldom hit because it has a very quick take-off and it flies parallel with
the road (Brown et al. 1986). The flight distance also has importance,
large birds take off over a greater distance than smaller birds (Dhindsa et
al. 1988).
Why do many birds fail to estimate the speed of a car?
When
a low-flying bird crosses the road, everything seems to it to be moving except
the coming car, as it can only see with one eye and therefore the car appears
to be stationary. Until it is too late to recognize the mistake. Its estimation
of distance is abeyance because its eyes are placed on either side of its
head. (Fremlin 1985, Dhindsa et al. 1988).
Crepuscular and nocturnal birds
The
headlights of the cars dazzle the birds. In Germany 51 Barn Owls Tyto alba
died on a 2,5km stretch within 3 weeks (Uhlenhaut 1976). In Denmark 12 Long-eared
Owls Asio otus, 2 Barn Owls, 1 Tawny Owl Strix aluco and 1 Short-eared
Owl Asio flammea + 15-20 flattened owls were found on a 75km long highway
stretch from mid February to mid March (Erritzoe 1999). In Lousiana, USA,
17 owls of two species: Great Horned Owl Bubo virginianus, and Southern
Barred Owl Strix varia were found dead on a 16km long stretch of highway
through a swamp (Ward 1934). Between 1984 and 1986 Hermandez (1988) examined
418 Little Owls, all traffic casualties, found in Spain, and suggests that
road casualties are the greatest non-natural mortality factor for this owl
in Spain. During a period of five years Aronson (1979) came to know of 15
Hume’s Owls Strix butleri which were killed by cars in Israel, indicating
that this owl often hunts animals on roads. The most common owl victim in
southern Brazil is the Burrowing Owl (Bencke & Bencke 1999). Also nightjars
are often mentioned in the literature as traffic casualties (Stanford 1954,
Winterbotton 1954, Harrison 1954, Benson 1955, Haverschmidt 1955, Müller-Using
1956, Brouwer 1992, Barlow & Gale 1999). A German study on chickens demonstrated
that the headlights of a car are presumably only in darkness able to dazzle
the chicken totally (Schoenemann 1977).
Irruptive species
In
winter roads have been temporarily closed because swarms of Bramblings Fringilla
montifringilla invaded roads passing through forests in Germany and
Switzerland in search of beech mast (Berthold 2001: 41). In the Netherland
a similar case has been reported (Osieck 1973). Also from North Zealand in
Denmark there is a case many years ago when in winter the road through a wood
was slippery with dead Bramblings (Own obs).
Scavengers
Buzzards
Buteo buteo and gulls are often themselves victims when they have landed
on a carcass on the road; for instance five Buzzards were killed on one winter
day in the former DDR because they were attracted by a traffic killed Hare
Lepus capensis (Borrmann 1969, Göransson et al. 1978: 85, Jones
1980). Scavengers themselves get killed and in turn are eaten by cats, foxes
and corvids (Slater 1994). The staple diet of the Wedge-tailed Eagle Aquila
audax in Australia is rabbits. The release of the Rabbit Calicivirus has
reduced rabbit numbers by up to 95% and there are now reports that the eagle
has turned to road kills in New South Wales. By collision with a car this
5kg heavy bird with a wingspan of about 2.5m can break the windscreen (Slater
1997). The Kite Milvus milvus is also known as a scavenger often seen
on carcasses on the road (Feindt & Göttgens 1967). Bosch (1989) states
that most birds of prey are killed not by collision with a car itself but
by collision with the antenna.
Are there species whose decline may be caused by traffic?
Nightjars
Caprimulgus europaeus may be declining in Europe chiefly because of collisions with cars (Göransson et al. 1978). Probably
this problem is the same in other countries, e. g. in Sarawak, Borneo (Harrison 1954) and many places in Africa (Stanford 1954,
Winterbottom 1954, Benson 1955, Haverschmidt 1955, Müller-Using 1956, Brouwer
1992). Also in the USA it seems to be a problem: on a 3,532km stretch 548 birds were found, of which
20 were Nighthawks Chordeiles minor (Russell 1938). The Red-headed
Woodpecker Melanerpes erythrocephalus living in many parts of North
America has declined heavily since 1960s due to habitat degradation and traffic accidents
(Winkler & Christie 2002). The drastic decline of the Little Owl in many
parts of Europe may also be partly due to because of the high number of road casualties (Hermandez
1988, Illner, 1992, Bultot 1996, Fajardo & Babiloni, 1996, Fajardo et
al. 1998).
Is it possible to monitor a population in a given area by means of the number of traffic accidents?
The
number of traffic killed House Sparrows vary much from place to place because
of local conditions and the sparrows’ exposure to traffic (Finnis 1960, Hodson
1960, Dunthorn & Errington 1964). The percentage of traffic-killed birds
is not by far the same for species with the same population density (Sargeant
& Forbes 1973), but it is logical that the population density is an important
factor, and all small passerines with territories within 150-200m from the
road are in the risk zone (Göransson et al. 1978: 55, 71). In a study
in Nebraska in 1941, 1942 and 1943, when the number of driven kilometres in
the same years are incorporated the rate of casualties found was in 1941
100, in 1942 109, and in 1943 46; if the traffic density was also rectified
the number would be 100, 137 and 64, which shows that the number of traffic
accidents in each year depends on the number of live animals or in other words
how good the breeding season was (McClure 1951). In Czechoslovakia the 15
(+ Blackbird) most seen live birds on highway were: 1576 Linnets Carduelis
cannabina, 1238 House Sparrows, 960 Skylarks, Alauda arvensis,
936 Rooks Corvus frugilegus, 781 Serin Serinus serinus, 697
Starlings Sturnus vulgaris, 603 Black-headed Gulls Larus ridibundus,
588 Goldfinchs Carduelis carduelis, 448 Pheasants Phasianus colchicus,
304 Sand Martins Riparia riparia, 273 Yellowhammers Emberiza citrinella,
254 Barn Swallows Hirundo rustica, 249 Partridges Perdix
perdix, 212 Swifts Apus apus, 190 White Wagtails Motacilla alba
50 Blackbirds Turdus merula. The 15 most often found traffic casualties
were: 46 Pheasants, 20 Partridges, 7 House Sparrows, 6 Rooks, 5 Blackbirds,
2 Barn Swallows, 1 Lapwing Vanellus vanellus, 1 Sparrow Hawk Accipiter
nisus, 1 Kestrel Falco tinnunculus, 1 Long-eared Owl Asio otus,
1 Song Thrush Turdus philomelos, 1 Red-backed Shrike Lanius collurio,
1 Skylark, 1 Tree Sparrow Passer montanus, 1 Goldfinch. If we compare
the number of carcasses found with the number of live individuals observed
in the motorway area, it corresponds to about 10% for the Pheasant, Partridge
and Blackbird, in the other species and in the overall total the figure is
about 1% (Havlín 1987). In comparisons ‘in ringed populations the losses caused
by collisions with vehicles reached 11-12% in Blackbirds and Song Thrushes,
in other species considerably less’ (Dunthorn & Errington 1964).
It is possible to monitor only common species to reduce the error due to the small number of road kills. ['For species with a high population density the counting af traffic casualties could show the range of different populations, local variation in density in the general yearly population cycle'] (Bruun-Schmidt 1994).
In America the number of the Whitetail Odocoileus virginianus has been estimated with traffic kill as a basis and the result used for banning hunting (Göransson & Karlsson 1979), and in England the westerly spread of the Muntjac Muntiacus reevesi is largely monitored via road-kills (Slater 1994). Here it must, however, be taken into consideration that a deer cannot like a bird fly when it has to cross a road and therefore cannot remove the risk by flying higher.
In which months are the birds killed by traffic?
Here
authors are in agreement both for North Europe and North America: April and
May and July-September (October). The former in connection with breeding activities
and reduced attention, the latter the dispersal of young and unexperienced
birds (Hansen 1969, Bräutigam 1978, Günther 1979, Smettan 1988). In Holland
the peak is June; in Hessen, Germany July (Bergmann 1974), and Hansen (1982)
gives August for Denmark. Around Berlin the peak for House and Tree Sparrows
is August, Chaffinch June and July, Greenfinch Carduelis chloris and
Song Thrush July and Barn Swallow August and September (Müller 1995), In South
Europe, however, the difference between the months of the year is not so distinct
because many of the migrating birds from northern Europe winter there (Göransson
et al. 1978: 85). In Sweden at the most 10% of the summer population
winters. One would expect the peak of traffic casualties to be dawn and dusk,
when this coincide with the peak of traffic mornings and evenings, but this
is not the case, because most have migrated and the rest are less active to
save calories (Göransson et al. 1978: 89). That so few adult birds
are killed in autumn is maybe because of their moulting period, when they
live more hidden (Bergmann 1974). In the winter months November to January
the fewest are killed, partly because there is less traffic and the cars do
not move so fast (Hodson & Snow 1965), and partly because the daytime
is shorter (Hodson 1960). There are about twice as many road collisions in
the breeding season as during the rest of the year in South Africa (Broekhuysen
1965).
How much influence has the weather on road kills?
Scott
(1938) found a direct relation between weather and the number of traffic casualties.
After heavy rain many insects in the USA are ‘washed’ down on the road and many of the terricolous insects and earthworms
come up to the surface and are there an easy prey for birds, and many birds
are road-killed (Zumeta & Holmes 1978). Contrary to this statement: if
there has been rain during the last half of the night, fewer road kills are
found (Dickerson 1939). In the USA on a 500 miles
trip by car fewer carcasses were found on the return trip when in the meantime
it had rained (Davis 1934). In storm and rainy weather the traffic casualties are much fewer than
in normal weather, whereas on close and sultry July days the number of killed
birds can be extremely high (Hodson 1960, Bergmann 1974). In 1931 in Minnesota many dead road-killed Bank Swallows Riparia riparia were found in two
cases, in one case the road was black with an estimated 1,000 birds. In both
cases on hot days (Stevens 1932). Swifts and swallows fly close to the ground
in moist, cold and rainy weather and are killed (Bräutigam 1978, Harding 1979,
Wascher et al. 1988). Birds prefer to fly against the wind when they
take off, therefore they will lose valuable time if they have to change their
direction (Göransson et al. 1978: 85). Black-shouldered Kites Elanus
caeruleus are most susceptible to collisions in Africa
during strong winds (Mendelsohn 1983). In Florida,
near Miami in 1958 the winter was very servere. In February John V. Dennis (1958) found
572 traffic killed birds on a one mile stretch and earlier the same month
96 birds, Myrtle Warblers Dendroica coronata represented 76% of all
the birds found during the first trip, and Tree Swallows Tachycineta bicolor
95% on the other. After heavy snow with many frost degrees a great number
of Lapland Buntings Calcarius lapponicus (estimated at 12,000) were
killed by cars in only one snowstorm, because they foraged on the snow-free
part of the highway (Gollop & Pulich 1978).
Other causes of traffic casualties
Foraging
birds or birds merely seeking the warm surface of the road mostly fly to the
left when a car approaches because the high vegetation to their right obstructs
the view and acts like a wall (Lüpke 1983). Birds are often killed by an overtaking
vehicles (Hodson 1962).
At which time of the day and on which day of the week are most birds road killed?
In
New England, USA most casualties were found in the evenings between 15.30 and 21.00 (Zumeta &
Holmes 1978).
In DDR and Czechoslovakia most were killed in the early morning hours (Lüpke 1983, Havlin 1987). In Sweden a study was conducted over 25 days and nights with a check every second hour. The peak was at seven in the morning and 17 in the evenings, with most in the morning, and Saturday-Sunday in the middle of the day. However, House Sparrow, Tree Sparrow and Barn Swallow had their peak about 12 o’clock also on weekdays. The day with most road kills was Saturday with 20, Sunday had 16, Monday, Tuesday and Friday 14, Wednesday 13 and Thursday had the fewest, 9 (Göransson et al. 1978: 49-50-51, 54). Schoenemann (1977) also got to the result that Saturday and Sunday are the days with most collisions, yet in his research mammals are also included.
|
|
|||
|
Species |
Males |
Females |
Source |
|
House Sparrow |
63* |
37* |
Hansen 1982 |
|
House Sparrow |
69 |
120 |
Hodson 1982 |
|
House Sparrow |
14 |
17 |
Govett 1960 |
|
Blackbird |
22 |
24 |
Beckmann 1961 |
|
Blackbird |
7 |
2 |
Govett 1960 |
|
Blackbird |
25 |
6 |
Finnis 1960 |
|
Greenfinch |
7 |
12 |
Govett 1960 |
|
Chaffinch |
8 |
7 |
Govett 1960 |
|
Yellowhammer |
5 |
6 |
Govett 1960 |
|
Various species |
67 |
33 |
Bruun-Schmidt 1994 |
|
Total |
287 |
264 |
|
|
*Hansen states only the percentage. |
|||
|
|
|||
|
Species |
Adult |
Juvenile |
Source |
|
House Sparrow |
232 |
43 |
Hodson 1962 |
|
House Sparrow |
409 |
173 |
Govett 1960 |
|
House Sparrow |
65 |
333 |
Bräutigam 1978 |
|
House Sparrow |
20 |
25 |
Scott 1938 |
|
Tree Sparrow |
45 |
15 |
Bräutigam 1978 |
|
Various species |
307 |
201 |
Bergmann 1974 |
|
Various species |
44 |
44 |
Bruun-Schmidt 1994 |
|
Various species |
39 |
25 |
Fuelhaas et al. 1989 |
|
Black-backed Magpie |
0 |
53 |
Burger & Gochfeld 1992 |
|
Little Owl |
25 |
328 |
Hermandez 1988 |
|
total: |
1186 |
1240 |
|
The percentage road-killed young birds versus adult birds?
In
summer more young birds are killed, as they do not yet have their full flight
power (Barnes 1936). In Denmark 5% young birds were found in May, 43% in June, 72% in July and 82% in August
(Hansen 1982). Bergmann (1974) recorded only juvenile Barn Swallows between
July-September and 93% Blackbirds killed in August were young birds. On the
other hand Göransson et al. (1978) found for Pheasant that here
the age distribution was the same as in the live population. In Germany the number was 65 adult and 333 juvenile House Sparrows, however, 90% were found
in August and September. The same author found for Tree Sparrow mainly in
July and August 45 adults and 15 juveniles (Bräutigam 1978). In another German
study the distribution was 307 adults and 201 juveniles, but the distribution
was very different from species to species: For the Barn Swallow the young
were nearly 80%, White Wagtail Motacilla alba and House Sparrow 60%,
Blackbirds 40%, against 20% Greenfinch and 12.5% for Skylark and Whitethroat
(Bergmann 1974). On a 1803km stretch in New Zealand
603 live Black-backed Magpies Gymnorhina tibicen were counted and 53
traffic killed which were all young birds (Burger & Gochfeld 1992). Among
88 road killed birds, which were age determined, 50% were young birds, but
in July the young birds were 63%, August 89% and September 86%, however, among
9 Barn Swallows 89% were young and surprisingly for the Blackbird 90% were
old birds (n = 21) (Bruun-Schmidt 1994:40
Are traffic casualties lean, normal or fat?
In
Pennsylvania in 1924 82 Screech Owls Otus
asio were road killed. Only ’few’ of them lean, the rest with a normal
body mass and many even with plenty of food in their stomachs (Sutton 1927).
Nine Long-eared Owls, eight Tawny Owls and 12 Barn Owls, all road killed,
were examined in 1992-94 in France and not found
lean (Massemin & Handrich 1997). From the USA reports of mass road killing of Lapland Longspurs Calcarius lapponicus
in cold winters, but these were mostly extremely fat and had their crops filled
with seeds gathered along the road (Gollob & Pulich 1978). Black-shouldered
Kite Elanus caeruleus is most susceptible to collision with cars while
carrying heavy prey items because its flight is then laboured and low over
the ground (Mendelsohn 1983).
Overview of the calculated total number of road killed birds or animals/year in different countries
Bulgaria:
more than 7 millions birds (Nankinov & Todorov 1983). 110,842 km2
63 road-killed per km2 /year
Denmark: 1,269,744 birds in 1957-58 (Hansen 1982)** 44,334 km2 29 road-killed per km2 /year
Denmark: 3,520,682 birds in 1964-65 (Hansen 1982).** 79 road-killed per km2/ year
Denmark: 3,272,518 birds in 1979-81 (Hansen 1982).** 74 road-killed per km2 /year
Denmark: 1.1 million birds in 1992-93 (Bruun-Schmidt 1994). 25 road-killed per km2 /year
Denmark: 350,000 birds (Thomsen 1992)* 8 road killed per km2 /year
England: nearly 4,000,000 birds at the beginning of the 1960s (Hodson 1966). 130,349 km2 31 road-killed per km2 /year
England: 2,500,000 birds 1961-61 (Hodson & Snow 1965). 19 road-killed per km2 /year
England: 27,000,000 birds (Errington 1971). 207 road-killed per km2 /year
Germany: 9.4 million birds (Fuellhaas et al. 1989).**** 356,270 km2 26 road-killed per km2 /year
Netherlands: 653,000 birds (Junkers & Vries 1977, cited in Dhindsa et al. 1988) 32,437 km2 20 road-killed per km2 /year
Spain: 10 million animals (CODA 1992). 491,258 km2 20 road-killed per km2 /year
Sweden: 750,000 birds i 1977 (Göransson et al. 1978:98)*** 449,605 km2 2 road-killed per km2 /year
USA: one million animals per day (Lalo 1987). 7,828,000 km2 47 road-killed animals per km2 /year
*Thomsen do not state how he has worked out this number. It looks as if it is strongly underestimated (Bruun-Schmidt 1994).
**Hansen (1982) has not worked out the importance of the habitats. Besides, in some cases the findings of one day has been multiplied by 30 to get the result for a whole month. This method is not sure. Moreover he states that Lolland-Falster where his study was conducted, maybe has more birds per area than the rest of the country (Bruun-Schmidt 1994).
***In these calculations the different habitats are taken into consideration, but not the density of the traffic (Bruun-Schmidt 1994)
****In these calculations the traffic density and different habitats are not taken into consideration (Bruun-Schmidt 1994)
Which species are most commonly road killed in Europe?
For more documentation about which species are most commonly road-killed
in Europe click here
|
||||||||||
|
Species |
Bulgaria |
Denmark |
England |
Finland |
France |
Germany |
Netherland |
Switzerland |
Sweden |
Total |
|
Total number recorded |
594 |
7724 |
7446 |
116 |
597 |
5615 |
1492 |
161 |
742 |
22.995 |
|
House Sparrow |
216 |
2258 |
3959 |
9 |
349** |
1407 |
393 |
35 |
197 |
8.823 |
|
Blackbird |
6 |
1038 |
989 |
15 |
668 |
717 |
14 |
54 |
3.501 |
|
|
Tree Sparrow |
299 |
479 |
335 |
16 |
24 |
33 |
1.186 |
|||
|
Song Thrush |
288 |
635 |
6 |
96 |
48 |
5 |
1.078 |
|||
|
Chaffinch |
2 |
400 |
265 |
4 |
2 |
242 |
15 |
5 |
9 |
944 |
|
Barn Swallow |
8 |
462 |
7 |
314 |
40 |
5 |
52 |
888 |
||
|
Pheasant |
139 |
254 |
4 |
18 |
143 |
88 |
647 |
|||
|
European Robin |
3 |
139 |
165 |
103 |
136 |
11 |
5 |
4 |
566 |
|
|
Yellowhammer |
1 |
214 |
14 |
2 |
182 |
4 |
417 |
|||
|
Mallard |
16 |
302 |
318 |
|||||||
Most commonly killed species in other continents
For more documentation about the most commonly road-killed species in other continents click here.
|
|||||||
|
Species |
California |
Illinois |
Iowa |
Ohio |
Pennsylvania |
Western States |
total |
|
Total number found |
136 |
134 |
143 |
21 |
460 |
459 |
1.353 |
|
House Sparrow |
28 |
84 |
42 |
10 |
223 |
387 |
|
|
Red-headed Woodpecker |
20 |
27 |
2 |
64 |
113 |
||
|
Screech Owl |
2 |
1 |
55 |
58 |
|||
|
Mourning Dove |
4 |
1 |
3 |
1 |
24 |
33 |
|
|
Northern Flicker |
1 |
2 |
3 |
12 |
8 |
28 |
|
|
Western Meadowlark |
15 |
2 |
6 |
23 |
|||
|
American Robin |
1 |
17 |
5 |
23 |
|||
|
Yellow-billed Cuckoo |
19 |
2 |
21 |
||||
|
Red-eyed Vireo |
18 |
18 |
|||||
|
Starling |
18 |
18 |
|||||
Traffic killed House Sparrows and Tree Sparrows calculated
as per cent compared with all other traffic killed species
Australia: 3.4% in 1988-90 (Lepschi 1992).
Bulgaria: 50.3% House Sparrows, 36.4% Tree Sparrows in 1979-80 (Nankinov & Todorov 1983).
Czechoslovakia: 63% (Holisová & Prbtel 1986),
Czechoslovakia: 9% (Havlín 1987).
Denmark: 37% in 1957-65 (Hansen 1982).
Denmark: 32.8% in 1979-81 (Hansen 1982).
Denmark: 4.4% in 1992-93 (Bruun-Schmidt 1994)
England: 50% in 1959-61 (Hodson 1962)
England: 45% (Errington 1971).
England: 50% (Johnson 1989).
France: 59% in 1978 (Vignes 1984).
Germany: 32% in 1973-76 (Smettan 1988).
Germany: 57% in 1974-77 (Bräutigam 1978).
Germany ( DDR): 37% in 1979 (Lüpke 1983).
Germany: 33%, Tree Sparrow 5% in 1982-91 (Müller 1995).
Germany: 14% in 1986-87 (Wascher et al. 1988).
Italy: 79% in 1980 (Quadrelli 1984).
USA near Boston, among 85 traffic casualties no House Sparrows (Zumeta & Holmes 1978).
USA, Iowa, 56% in 1926 (Spiker 1927).
USA, New Jersey and Arisona, 43% in 1938 (Russell 1938).
USA, Illinois, in 1938 78% (Starrett 1938).
And a count of all live birds seen on or near the road:
India: 29.47% of all live birds seen on the roads were House Sparrows, but by four transects, each of 1km length near the road the House Sparrow was only 9.37% of the total population (Dhindsa et al. 1988).
Has traffic killing any influence on the bird populations?
Studies
and estimates of the influence of road kills on bird populations is lacking
(Bezzel 1982). Traffic kills represent an inconceivably great number of birds
worldwide. In India, e. g. on a 5km stretch of the National Road number11
near Bharatpur 219 birds were found in a year (Sharma 1988), and in New South
Wales, Australia on a 301 km road between Canberra and Lake Cowal between
1970 and 72 1095 traffic casualties were found (Vestjens 1973). These few
quite normal examples (the first 44 birds year/km, the second 2 birds year/km)
should be enough to demonstrate how many birds are yearly victims of traffic,
when one takes into consideration that only in Denmark there are nearly 72.000km
public and 15.000 private roads (Skriver 2001).However, Bergmann (1974) wrote
that habitat changes and pollution is a much greater cause of the decline
of some species.
Dunthorn & Errington (1964) found that for Song Thrush, Blackbird, Linnet and House Sparrow respectively 11, 12, 3 and 4% of the young birds are killed, and for the House Sparrow approx. 5% of the total population within the risk zone of the road are victims. In England 13% of all House Sparrows are killed by traffic (Hodson & Snow 1965). By contrast, Hansen (1982) found that nearly all House Sparrow young in the population were killed in the traffic at a highway near Copenhagen. In a German study 1973-76 4.8% of the House Sparrow population was road killed, 8% Blackbirds and 4% Greenfinches; all bird species taken together were worked out to 0.5% in farmland and 3.6% in built-up areas (Smettan 1988). In Sweden only 1-4% of most species are traffic killed, but for some species it is 10%. Most exposed are Pheasants, Partridges, hawks, Rooks and owls in that order (Göransson et al. 1978). In Western Australian 28,687 birds were ringed in an area between January 1984 and December 1985 and only 10 of these were found as road casualties, all within 1km from the ringing place (Brown et al. 1986). Only the Nightjar family, the Red-headed Woodpecker and maybe the Little Owl seem to have declined drastically because of traffic, as already mentioned.
Already in 1929 Linsdale wrote that birds profit from using the roads even when traffic kills are taken into consideration and most of the victims are quite common species.
Proposed measures against traffic kills
For
mammals and reptiles many measures to prevent road kills have been made, but
the fact that most birds can fly makes nearly all the proposed arrangements
for mammals superfluous for birds. The following is a summary of recommendations
special for birds taken from the papers consulted in this work:
Studies on migrations and population changes to preserve local populations and to minimize the impact on ecosystem equilibrium (Lodgé 2000).
Making speed bumps through forests with rare owls at the most critical portions and construction of roads through national parks with rare owls should be avoided (Bencke & Bencke 1999).
Most animals are killed near crossroads and where highway networks meet, because the highway here is wider and often with a rich vegetation (Havlín 1987, Madsen et al. 1998), so these places should maybe be more sterile (Madsen et al. 1998).
To avoid road collisions with Little Owls it is desirable to plant trees or scrub near roads, or even better, to place 2m high perches 5m from the road border and 10 to 15m apart, and illuminate the road where many owls are killed (Hermandez 1988). Areas with Olive trees is a strong habitat preference for the Little Owl, therefore preserve them (Fajardo et al. 1998).
Plant high hedges on both roadsides on elevated banks and make corridors through farmland with wide verges to link otherwise isolated habitats (Slater 1994). Make hedge plantations on roadsides on embanked road sections (Lodgé 2000).
Reduce the speed (Fuellhaas et al 1989).
Restrictions against leaving dead animals on the roads and a alarm system installed on the cars to warn the birds in time (Dhindsa et al. 1988).
Driver education and adaptation of driving (Havlín 1987).
Do not plant hedges on both sides of roads with dense traffic (Finnis 1960, Lüpke 1983).
Do not plant trees or bushes along the roads with berries and fruits that birds like to eat. On a Texas highway Silverberry Eleagnus pungens was planted in the middle of the road. Between 8 March and 5 April 1981 298 dead Cedar Waxwings Bombycilla cedrorum were found along 275m of such a planting and 133 birds on 11 March. The speed on the highway was only 55 mile ph = 88km (Dowler 1982).
Statements that deal with the impact of roads yet disregard long-term effects should be rejected. Extra care should be taken in planning new roads, not merely in deciding how to construct them, but primarily in deciding whether or not to construct them (Zande et al. 1980).
Farmers should not waste so much corn on the roads (Günther 1979).
The largest number of traffic casualties are found where there is plentiful of vegetation (Heinrich 1978).
Better planning of the highway environment should be considered as a means of reducing the death toll, and, most important, do not plan roads through valuable habitats (Dickinson 1939, Wascher et al. 1988). Especially moors, swamps, ponds, fallow lands and nearby forests are important habitats where no roads should be planned, and it should also be avoided to let a road run as a borderline to forests, meadows or lakes (Institut für Naturschutz und Tierökologie 1977).
Remove the road illumination through villages and in towns (Davis 1934), it attracts many insects (Institut für Naturschutz und Tierökologie 1977).
Make a steppe habitat with short grass as a ‘bufferzone’ next to the road followed by a zone with flowers, bushes and trees and small lakes, established when the road is constructed, free from human access (Institut für Naturschutz und Tierökologie 1977).
Plant hedges of whitethorn on embankments to force the birds to fly higher when crossing them (Ratcliffe 1974).
The vegetation along the highways in America has very little effect on the number of traffic kills (Joselyn et al. 1969: 8-9).
In the USA the fewest traffic kills are where there is sparse vegetation (Russell 1938, Seeker 1960).
Frequent use of the horn when birds are on the road. Building the highways wide and straight (Finnis 1960).
McClure (1951) concluded that road kills were proportional to the density of cover along the roads, to the age composition, and to the density of the wildlife population rather than to the amount of traffic and the degree of road improvement, e. g. the increasing speed of traffic.
A net stretched on the radiator to catch the birds (Creutz 1935)!
Dill (1926) examined the stomach of about 20 dead Red-headed Woodpeckers and found that the content was bread, crumbs, sweet corn, bits of doughnuts and pieces of apples. His advice is therefore, do not throw food-scraps into the roads.
Discussion
The
number of bird traffic casualties worldwide must be astronomic, considering
how many km of roads exist. It becomes still more surprising how the birds
survive if for a moment we consider all the other man-made causes of bird
deaths like window collisions, electrocutions and other collisions with human
constructions. (Robin K. Panza from the Carnegie Museum in Pittsburgh, Pennsylvania
pers. comm.): “I’ve always been more impressed by TV-tower mortality, where
100 or more Red-eyed Vireos die in a single night than by traffic mortality
as a population problem. We have [in our museum]1.300 carcasses listed as
tower kills, and 1.100 from hitting windows, compared to less than 500 road
kills”.
As seen from the above there are great differences in the conclusions of the works by the various authors. There seems, however, to be great agreement among authors in classifying breeding habitat on or near roads as generally of less quality because of the many disturbances, compared with farther away from the road, which is demonstrated by worse breeding success than that found in real nature. Roads intensifying the toxic contamination among roadside population, increase the habitat fragmentation with limited population exchange as a result, and induce higher mortality, which can have a strong impact on small-sized populations (Lodé 2000). However, as a feeding habitat outside the breeding season most authors consider the advantage greater than the risk of being killed by the traffic. Roads save many birds in cold winters because road kills are in no report recorded having a lean body mass. The ‘black spots’ where most birds are killed seem to be where there are gaps and openings in hedges, hedges on both sides of the road, traffic centers, where the highway is wider and with a luxuriant vegetation and in villages with many gardens where the bird population is larger. The roads with fewer accidents are those with long straight parts without much vegetation along the roadside. Table 6 shows better than many words that the number of road-kills found depends not only upon the density of populations along roads, but also on the powers of observation in the reporters, one having found a bird for each 2km and another for each 3,889km! The same table shows an average of 62km for each found carcass found by car (omitting the three unlikely: 905-,2,000- and 3,889km), the half by bicycle, 28km, and 17km by walking. If we take all the possibilities of error into consideration: birds overlooked, taken by scavengers or worn down by cars, half of 17km , 8.5km/day is maybe more realistic. With 87,000km of roads in Denmark (Skriver 2001) this will make 10,235 birds per day and 3,700,000 traffic-killed birds in a year, not far from the estimated 3.2 million given by Hansen (1982) for the years 1979-81.
The most often traffic-killed bird worldwide is without any doubt the House Sparrow with approx. 62% of all birds killed in many countries, see table 3 where most killed in Europe is the House Sparrow with 8,430 victims, compared with all other birds together 13,575. The Blackbird is number two with 2,784, Tree Sparrow number three with 1,170, Song Thrush 1,030, Chaffinch 929, Barn Swallow 852, Robin 557, Pheasant 504, Yellowhammer 417, Dunnock 235, Starling 145, Great Tit 112, Whitethroat 109, Linnet 101, Wood Pigeon 60, Brambling 59, Rook 51, Goldfinch 51, Hooded Crow 49, White Wagtail 45, Pied Flycatcher 39, Blue tit 38, Black-headed Gull 36, Magpie 20, House Martin 18, Mallard 16, Red-backed Shrike 15, Partridge 15, March Warbler 11. The last 15 species not mentioned here have less than ten road kills. In comparison the American road killed birds are: House Sparrow 387, Red-headed Woodpecker 113, Screech Owl 58, Mourning Dove 33, Northern Flickers 28, Meadowlark 23 American Robin 23, Yellow-billed Cuckoo 21, Starling 18, Red-eyed Vireo 18, American Goldfinch 17, Chuck Will’s Widow (nightjar) 14, Bronzed Grackles 14, Red-tailed Hawk 13, Common Cardinal 13, Great Horned Owl 11, Barred Owl 11, California Shrike 10. The last 27 species not mentioned here have less than ten road kills. The European list is dominated by passerines, with only a duck, a gull, a pigeon, a pheasant and Partridge as non-passerines. Unlike the American list which have hawks, owls, pigeons, cuckoos, nightjars and woodpeckers as common road victims, families which all also occur in Europe. However, in the European list it must be by chance that no owls with their nocturnal habits are mentioned because they are otherwise often mentioned in the literature (Uhlenhaut 1976, Hermandez 1988, Illner, 1992, Fajardo & Babiloni, 1996, Fajardo et al. 1998, Erritzøe 1999), and from Israel (Aronson 1979).
Most authors ascribe to the speed of the vehicles great importance for the number of road kills, although as to the effect of the density of the traffic and what role it plays for collisions with birds a great difference exists between authors. Some found that roads with much traffic had more accidents, others that dense traffic gives birds a faster ‘learning effect’ so that they learn to cross the road at a greater hight. In other words that the solitary fast-driving car kills more birds due to the element of surprise.
The behaviour of the different bird species seems to be of great importance, e. g. some birds fly lower than others and are therefore more exposed to collisions. Other birds make diving maneuvers or turn around, which may be is a good strategy when attacked by a raptor, but catastrophic in the case of an approaching car. The headlights of cars seems to be of great importance for collisions in the dark for nocturnal birds like owls and nightjars. It is only possible to monitor very common bird populations by means of road casualties, because it is connected with many diverse factors how many road kills happen to most bird species. Most collisions occur in the breeding season, roughly about 50%, about this all authors are in agreement; the only exception is the countries around the Mediterranean, where many new species now winters and the numbers are therefore more equal all the year round. Some authors found most casualties after rain, others in warm weather, stormy weather or snowstorms. Mornings show most road kills, but sparrows and swallows peak about midday.
About
the question of which sex is more often killed, there were great differences
among authors, and the same goes for age distribution, although for the Barn
Swallow the overwhelming number were young birds. Surprisingly, few cases
of lean body mass on road killed birds are reported. The overall picture of
the estimated total number of road kills from different countries demonstrates
how difficult it is to work out a realistic picture of road deaths. In this
list the area in square km for each country is given as a very rough value
for comparative reason. By excluding the extremes among the results: Thomsen,
Errington, Göransson et al. and Lalo, an average among the rest of
38.6 traffic killed birds per km2/year. Keeping in mind all the
sources of error, which are mentioned at the beginning of this paper, the
double number will may be be more realistic.
The House Sparrow is the most common victim to traffic – often 50% or more of all bird casualties, but now with a falling tendency, most probably because it is a declining species. In spite of this, only 5-13% of the House Sparrow population in England are said to be traffic killed, and in Sweden the number is even lower, 1-4% for most species but 10% for Pheasants, Partridges, hawks, Rooks and owls (Göransson et al. 1978)..
As the number of birds worldwide has decreased and the number of birds varies from year to year due to the varying success of the breeding season in different areas a comparison between periods is difficult. In the former DDR in the year 1975 one bird was killed for every 1.58km, in 1976 2.37km, and in 1977 (with bad weather) 5,12km (Günther 1979). In 1976-78 in Czechoslovakia considerably more birds were killed than in 1981-1985, in numbers per 100km : 1976: 0.30, 1977: 0.23, 1978: 0.18. In the last period the numbers were between 0.01 and 0.05 The count was made from a car which ran at 60-70km/h, and only dead birds on the paved road were counted (Holisová & Orbtel 1986). Hansen´s (1982) numbers suggest the same: 3.5 million in 1965, and 3.2 million in 1981. Tables 3 and 4 do not give any hint of a decrease or increase in traffic casualties.
The chief question one must pose after reading this survey of papers about traffic casualties must be wheather natural selection will sharpen the evolution of birds’ road behaviour or, in other words, make some species develop an ‘antimortality strategy’? In an Australian paper the author records that old birds fly first and the young birds last when a car approaches. The great number of young birds killed in summer and early autumn is not surprising in view of the greater number of juveniles at that time, their lack of experience, and the adults’ more reclusive behaviour during the moulting period.
Most surprising is maybe the Barn Swallow, which is a frequent bird on the road and especially often seen flying low over the road very near vehicles, but in spite of this very few adults are hit by cars, and the few unlucky ones are nearly always get killed during the first days after arrival. An exception was a report of more than 500 adult swallows killed on roads in and around the Ebro Delta, Spain in spring 1992 due to bad weather (Estrada & Riera 1995). The Barn Swallow is the species where the difference between the number of adult as opposed to juvenile road kills is greatest; the Blackbird is an example of the opposite: both Bergmann (1974) and Smettan (1988) found that 60% of the road-killed Blackbirds in summer were adults and Lidauer (1983) stated that older Blackbirds from towns had more old wounds, which does not support the idea of a learning effect.
If
the density of traffic at one site is low, the probability that birds living
there will learn to beware of the cars will be small, and the same will apply
to young birds, migrating birds and newly arrived ones, but if the traffic
density is high, the birds will more easily learn to take care (Bergmann 1974).
On a highway in Louisiana, USA, which had been opened a few weeks earlier, 17 owls – Great Horned Owls and
Southern Barred Owls – were found road-killed within a stretch of only 16km
through a swamp (Ward 1934). Also Havlin (1987) and Lodgé (2000) reported
how new opened roads have more traffic accidents, but the incidence may stabilize
later
In Illinois, USA, in 1925 134 birds were found road-killed on 481km of highway. That makes one for every 3.6km. The author wrote that ”the average speed of from twenty-five to thirty-five miles [40-60km] is maintained by nearly all cars” (Flint 1926). This example indicates that birds have learned to be more wary of the cars since 1925. Even at a speed of 100km, a much heavier traffic, but of course also a much smaller population, the result today would rarely reach such a high number (table 2).
However, the question wheather natural selection has modified bird behaviour on roads is impossible to answer before long-time studies on the same sites have been conducted, in which not only the traffic-killed birds are counted, but the live populations along the roads are monitored by point counts or transects, and any changes in population size, density of traffic and the maximum speed of cars are taken into consideration.
The
next important question is whether there are different abilities to learn
the danger of traffic in different populations of the same species, and here
this review gives some hints which look promising for future research
The omnivorous corvids are worldwide frequent guests on roads where they e. g. forage on carrion. Nevertheless, this family is very rarely reported road killed in most countries, America, Bulgaria, Denmark, French, Germany, South Africa, and Switzerland. Finland and Sweden are the great exception; the Hooded Crow accounts in Finland for 40% of all traffic accidents and the Magpie for 17%. This result confirm as earlier Finnish study, according to which 23% were Hooded Crows (Moilanen 1978, here cited in Korhonen & Nurminen 1987). In Sweden a calculation of the number killed in per cent of the calculated total population has been carried out: Magpie 0.9-1.6%, Hooded Crow 0.8-1.2% but Rook 10-11% (Göransson et al. 1978). In Schleswig-Holstein, Germany on a 43.2km long stretch there were three Rook colonies and the Rooks from there were often seen foraging in the roadside or even eating carcasses directly on the road, but in spite of this none were found traffic-killed (Heinrich 1978). In another German study near Stuttgart, where Hooded Crow, Rook and Magpie were often seen on the roads, none were found among 200 road-killed birds (Smettan 1988), and only one corvid (a Jay) was found among 508 other bird carcasses (Bergmann 1974). In Denmark 19 Rooks and 7 Magpies were found in a c. 220.000km study (Jensen 1996). In South Africa only one dead Pied Crow was found among 585 traffic kills. All three crow species living in the Cape Province are very often seen on the roads seeking carcasses (Broekhuysen 1965). However, from other countries the figures show higher numbers: In a study from Czechoslovakia there were 8% Rooks. Two papers from England show 3% and 4% Rooks among respectively 864 and 585 road kills. Italy recorded 3 Hooded Crows among 133 bird casualties. From six studies in America, all with small numbers of road-killed birds, none were corvids, but on a journey from Ohio to the Pacific Coast 3 crows were recorded, 3 Black-billed Magpies and surprisingly also 3 Ravens among a total of 106 casualties. On a 46,400km journey through many countries in Europe, Morocco and Turkey only 4 Carrion Crows 2 Hooded Crows, 1 Rook, 9 Jackdaws Corvus monedula, 9 Magpies and 2 Jays Garrulus glandarius were found (Haas 1964).
Jesper Bruun-Schmidt wrote in his study from Denmark (1994): [’Some species are apparently better adapted to the life on the roads. For instance the Starling, the Hooded Crow, the Jay and the White Wagtail are all often seen on the roads, but only the Hooded Crow are in a few cases found traffic-killed’]. In New Zealand 603 live Magpies Gymnorhina tibicen were counted and 53 traffic- killed, which were all young birds. When both age groups were on the road together the old birds flew before the young when a car came nearer (Burger & Gochfeld 1992).
But in many populations not only corvids seem to have learned how to use roads without being killed. In Osnabrück, Germany, no White Wagtails were found, even though they were commonly seen on the roads; the author wrote that their reactions were very effective, and often when the car had passed, the birds at once came back on the road (Fuellhaas et al 1989); in Czechoslovakia 190 White Wagtails were seen on the roads, but none found dead among 99 traffic casualties (Havlin 1987). In a Swedish study from 1973-76 no Wagtails are mentioned among 742 casualties (Göransson et al. 1978: 40-41). However, in Hessen, Germany among 625 traffic casualties there were19 White Wagtails (Bergmann 1974). In his studies 1957-58, 1964-65 & 1979-81 Hansen mentioned no White Wagtails among 7,724 traffic casualties, but in his figures there are unfortunately 1,102 unspecified birds. In France there were among 597 road kills 10 White Wagtails (Vignes (1984).
The
Starling figures seldom on lists of road-kills even though it is such
a common bird, often seen on or near roads. One exception is the paper by
Govett (1960) who recorded 42 Starlings among 585 casualties between 1949
and 1959. The author gives no information about where he counted traffic accidents,
presumably somewhere in the north of England, because the journal “Naturalist”, in which the paper was published, is a periodical
for the North of England. The only information about the Starlings is that
28 adults and 14 juveniles were found.
In America a great number of woodpeckers are traffic-killed, earlier mostly the Red-headed Woodpecker and already in 1926 four alarming papers appeared (Baldwin, Dill, Flint, Hadley), followed by Sharp and Clarke i 1930. In 1934 among 353 road-killed birds Baumgartner found 33 Red-headed Woodpeckers, only surpassed by 166 House Sparrows, and at midsummer in Illinois Flint (1926) 20 Red-headed Woodpeckers, mostly young birds. During a 354km trip in Iowa in August Dill (1926) found 21 dead Red-headed and 182 live ones. However in the rest of the world woodpeckers figure rarely as road kills. On a journey around Europe, Turkey and Morocco, a total of 46,400km, partly on bicycle partly by car, only 2 Green Woodpeckers Picus viridis, 1 Grey-headed Woodpecker Picus canus and 2 Great Spotted Woodpeckers Dendrocopus major were found (Haas 1964). What can be the reason? (Dayton Stoner, 1932, cited in A. C. Bent 1939: Life History of North American Woodpeckers. Smithsonian Inst., Washington, D. C. p 206) on a 211- mile trip in 1924 on well-gravelled roads in Iowa found 105 dead animals 39 of which were Red-headed Woodpeckers. He claims that the explanation of this high number is that this species feeds on insects and waste grain along the roads, and they delay taking wing before an approaching car and do not quickly gain sufficient speed to escape a car. Unfortunately no modern study of traffic accidents has been made, which might give a hint of wheather the Red-headed Woodpecker has learned to be more careful when it frequents roads. Since 1966 it has declined annually 2.2% in the eastern USA, and it is also declining over most of its other range due to habitat destruction and collisions with motor vehicles (Winkler & Christie 2002). An enquiry among American curators gave a hint. Janet Hinshaw from the University of Michigan believes that the many road kills were due to their habit of nesting in wooden fence posts, which were formerly common along roads. As the birds flew to or from their nests, they crossed the road and were killed. In North Carolina it is still a rather common species with about 25 road-killed Red-headed Woodpeckers given to the museum in Raleigh since 1960 (John Gerwin in litt.) as opposed to only two among 460 carcasses delivered to the Carnegie Museum in Pittsburgh (Robin K. Panza in litt.).
All the common traffic victims today are quite numerous bird species, and the few studies which have tried to estimate the percentage give such low figures – none higher than 10% of the population and most less than 5% – that there is no reason for concern for the near future.
A glance into the future: In the event of specific environmental changes like, e. g. still more roads, cleaner and less noisy cars, more human settlements and fewer and fragmented natural habitats, so that the carrying capacity of the natural environment has gone beyond the possible, the genetic basis for rapid and diverse micro-evolutionary development affecting patterns of future road use may start to work, so that more and more bird species will be forced to forage on roads. With increased traffic density and traffic jams more and more garbage dumps will be left on the roads, and with high traffic density natural selection will presumably work faster, because the birds will learn about the danger on the roads, so that fewer birds will become victims. The global warming can end up with conditions similar to those currently prevailing in the Mediterranean region, where new ecological niches have been created for the greater and greater number of formerly migratory but now resident birds. The scenario will be still worse when the desertification of the Sahel in Africa continues, because that will means still more migrants forced to find new winter sites in the Mediterranean countries. All these circumstances may work towards more use of our roads by an increased number of bird species, and the roads will more or less also serve as corridors between small fragmented habitats for weak flying species
If this image of the future is realistic, there must still be a great demand for more research about how we can make our roads more 'user-friendly' for the avian fauna, because the future advantages will presumably be greater than the disadvantages, and therefore birds will use our roads in increasing number, with or without our accept.
Acknowledgement
I
am in great debt to Prof. Anders Pape Møller for his careful criticism of
the manuscript. Dr Jevgeni Shergalin has made a great achievement in compiling
all the papers in Russian and other Eastern European languages, and Bent Sunesen,
Copenhagen has checked the English formulation of the text. My
thanks go also to Niels Linneberg, who as usual sorted out all the computer
problems.
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*
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Clarke, H. 1930: Birds killed by carmobiles. Bird-Lore 32 (4): 271.
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C. L. W.” 1930: Examine birds killed by carmobiles. Bird-Banding 1 (4): 190.
*CODA (Coordinadora de Organizaciones de Defensa Ambeintal) 1992: I Jornadas para elestudio y prevencion de la mortalidad de vertebradod en carreteras. 3 Vols. Madrid.
Coleman, B. 1968: Common Gulls and Blackbirds feeding on road casualties. British Birds 61: 227.
Cooke, A. S. 1980: Observation on how close certain passerine species will tolerate an approaching human in rural and suburban areas. Biol. Conserve. 18: 85-88. (Not about road-kills)
Cottam, C. 1931: Birds and motor cars in South Dakota. Wilson Bull. 43 (4): 313-314.
Creutz G. 1935: Strassentod. Orn. Monatschrift 60: 189-192.
*Dambach, C. A. 1956: Roadside use has a part in the conservation program. Tenth Short Course on Roadside Development, Ohio State Univ., and Ohio Dept. of Highways. pp. 16-22.
*Danilenko, A.K., & E. A. Danilenko, 1981: Vliyanie avtomobil’nykh dorog na formirovanie sovremennykh territorial’nykh gruppirovok naseleniya ptits [Affect of carmobile toads on formation of the modern territorial groups of bird population]. Ekologiya i okhrana ptits: Materialy 8-i vsesoyuz.ornitol. konferentsii [Ecology and conservation of birds: Materials of the 8th All-Union Orn. conf.]. Kishinev: 67. In Russian.
Davis, B. W 1940: Mortality of wildlife on a Texas highway. J. Wildlife Management 4: 90-91.
Davis, F. T. 1930: Causes of mortality among birds. Bird-Lore 32 (4): 255-257.
Dennis, J. V. 1958: Death on the highway. Audubon Magazine 60 (4): 159
*de Roos, G. T. 1977: [Animal mortality from traffic on Vlieland and Terschelling]. Levende Nat.
80 (11): 264. (In Dutch).-
*Devine, A. & D. G. Smith. 1985: Eastern Screech Owl (Otus asio) mortality in Southern Connecticut. Connecticut Warbler 5 (4): 47-48.
Dhindsa, M. S., J. S. Sandhu, & H. S. Toor. 1988: Roadside birds in Punjab (India): Relation to mortality from vehicles. Environmental Conservation 15 (4): 303-310.
Dickerson, L. M. 1939: The problem of wildlife destruction by carmobile traffic. J. Wildl. Management 3: 104-116.
Dill, H. R. 1926: Is the carmobile exterminating the woodpecker? Science 63 No. 1620: 69-70.
Disney, H. J. de S. & P. J. Fullagar 1978: A note on road kills. Corella 2: 89
Dowler, R. G. & G. A. Swanson. 1982: High mortality of Cedar Waxwings associated with highway plantings. Wilson Bull. 94 (4): 602.
Dreyer, W. A. 1935: The question of wildlife destruction by the carmobile. Science 82 No.2132): 439-440.
Dunthorn, A. A. & F. P. Errington 1964: Casualties among birds along a selected road in Wiltshire. Bird Study 11: 168-182.
*Eckert, K. 1978. Invasion of great gray and boreal owls, winter 1977-78. Loon 50:63-68.
*Enklaar, H. 1962: Verkeersslachtoffers in Zeeland in 1961. Het Vogeljaar 10 (2): 329.
Errington, F. P. 1971: Bird deaths on roads. Ibis 113: 416.
Erritzøe, J. 1999: Causes of mortality in the Long-eared Owl Asio otus. Dansk Ornitologisk Forenings Tidskrift 93:162-164.
Erz, W. 1977: Tierwelt und Strasse, Problemübersicht und Planungshinweise. Jb. Naturschutz und Landschaftspflege 26: 91-115.
*Estrada, J. & X. Riera, 1995: [High mortality of Hirundinidae on roads in and around the Ebro Delta in spring 1992]. Butll. Grup Catalá d’Anellam 12: 17-22. In Spanish with English summary.
*Fajardo, I. & G. Babiloni. 1996: Estado de conservación de la rapaces nocturnas (O. Estrigiformes) en el Mediterráneo Occidental. in: Muntaner, J. & J. Majol (eds.) Biology and Conservation of Mediterranean Raptors. Monografias 4. SEO, Madrid. .
Fajardo, I., V. Pividal, M. Trigo, & M. Jiménez. 1998: Habitat selection, activity peaks and strategies to avoid road mortality by the Little Owl Athene noctua. Alauda 66 (1): 49-60.
*Feindt, P. & H. Göttgens. 1967: Überwintrende Rote Milane (Milvus milvus) in Süd-Niedersachsen an ihren Sammel-Schlaf- und Nährungsplätzen. Vogelwelt 88 (1): 8-19.
* Ferris, C. R. 1974: Effects of highways on Red-tailed Hawks and Sparrowhawks. M. S. Thesis. West Virginia University, Morgantown. Pp. 60.
*Ferris, C. R. 1979: Effects of Interstate 95 on breeding birds in northern Maine. J. Wildlife Management 43: 421-427.
*Fetisov, S. A. 1990: [On the death of birds on the motor patch of the Pskov region]. Vestn. Leningr. Univ. Biol. 1990: 20.26.
*Fetisov, S.A. 1991: Gibel’ ptits na dorogakh v Pskovskoi oblasti [The bird loss on car-roads of the Pskov Region]. Materialy 10-i vsesoyuz. ornitol. konf. [Materials of the 10th All-Union Orn. Conf.]. Minsk, 2, 2: 266-267. In Russian.
Finnis, R. G. 1956: Bird casualties on roads. Bull. Brit. Orn. Club 76: 150-152.
Finnis, R. G. 1960: Road casualties among birds. Bird Study 7: 21-32.
Flint, W. P. 1926: The carmobile and wild life. Science 63, No. 1634: 426-427.
Foppen, R. & R. Reijnen, 1994: The effect of car traffic on breeding bird populations in woodland. II. Breeding dispersal of male Willow Warblers (Phylloscopus trochilus) in relation to the proximity of a highway. J. Applied Ecology 31: 95-101.
Fremlin, J. 1985: Why do birds collide with cars? New Scientist 1985: 60-61.
Fuellhaas, U., C. Klemp, A. Kordes, H. Ottersber, M. Pirmann, A. Thiessen, C. Tshoetschel, & H. Zucchi. 1989: Untersuchungen zum Strassentod von Vögeln, Säugetieren, Amphibien und Reptilien. Beiträge Naturkunde Niedersachsens 42: 129-147.
Gander, F. F. 1927: Birds slaughtered by carmobiles. Auk 44 (3) 575.
*Geuze, J. J. 1974: Verkeersslachtoffers onder roerdompen. Het Vogeljaar 22 (6): 933.
Gollob, T. & W. M. Pulich. 1978: Lapland Longspur casualties in Texas. Bull. Texas Orn. Soc. 11 (2): 44-46.
Göransson, G. & J. Karlsson 1978: Changes in population densities as monitored by animals killed on roads. Statens Naturvårdsverk. PM 1151. Sweden
*Göransson, G. & J. Karlsson 1982: Hunting and Road Mortality in the Pheasant and the European Hare in South Sweden. Trans. Intern. Congr. Game Biol. 14: 343-349.
Göransson, G., J. Karlsson, & A. Lindgren. 1978: Vägars inverkan på omgivande natur. Rapport från Statens Naturvårdsverk. Pp.124.
Govett, J. R. 1960: Mortality of wild birds on roads. Naturalist 872:5-6.
Grajetzki, B.1991: Untersuchungen zur Nahrungs- und Brutbiologie des Rotkehlchens (Erithacus rubecula L. 1758) in Bereich der Bornhöveder Seenplatte. Diplomarbeit, Universität Kiel.
Grajetzki, B. 1992: Nahrung und Brutverhalten von Rotkehlchen-Weibschen Erithacus rubecula einer schleswig-holsteinischen Knicklandschaft. Die Vogelwelt 113: 282-288.
Grue, C. E., T. J. O'Shea, & D. J. Hoffman,1984: Lead concentrations and reproduction in highway-nesting Barn Swallows. Condor 86 (4): 383-389. [With many references].
Günther, U. 1979: Eine Untersuchung zur Frage der Gefährdung unserer Vogelwelt durch des Straßenverkehr. Thüringer Ornithologische Mitteilungen 25: 3-14.
Haas, W. 1964: Verluste von Vögeln und Säugern auf Carstrassen. Orn. Mitt. 16 (12): 245-250.
Hadley, A. H. 1926: Birds killed by carmobiles. Bird-Lore 28 (4): 314-315.
Hadley, A. H. 1927: Wild life and carmobiles. Bird Lore 29: 391-392.
Hadley A. H. 1930: The killing of birds and animals by carmobiles. Bird-Lore 32 (6): 464.
Hansen, L. 1959: Hvor mange dyr dræbes i trafikken? Naturens Verden 1959: 102-128.
Hansen, L. 1969: Trafikdøden i den danske dyreverden. Dansk Ornitologisk Forenings Tidskrift 63: 81-92.
Hansen, L. 1982: Trafikdræbte dyr i Danmark. Dansk Ornitologisk Forenings Tidskrift 76: 97-110.
Harding, B. D. 1979: Road mortality of swifts. Brit. Birds 72 (8): 392.
Harding, B. D. 1986: Short-eared Owl mortality on roads. Brit. Birds 79 (8): 403-404.
Harrisson, T. 1954: Nightjars sitting on roads at night. Ibis 96: 626.
Haverschmidt, F. 1955: Nightjars sitting on roads at night. Ibis 97: 371-372.
Havlin, J. 1987: Motorways and birds. Folia Zoologica 36 (2): 137-153.
Hawkins, R. H. & J. H. Judd 1972: Water pollution as affected by street salting. Water Resources Bull. 8 (6): 1246-1252. (Not about traffic accidents).
Hawkins, R.M. 1946. Bald eagle feeding on the highway. Auk 63:85.
Heinrich, D. 1978: Untersuchungen zur Verkehrsopferrate bei Säugetieren und Vögeln. Die Heimat 85 (8): 193-208.
Heldt, R. 1961: Vogelverluste auf Carstrassen. Orn. Mitt. 13 Heft 11.
*Hendrickson, G. O. 1932: Birds found dead on Iowa Primary Roads. Proc. Iowa Acad Sci. 39: 251-252.
Hendrickson, G. O. 1933: An August day’s toll of birds’ lives on primary Iowa roads. Wilson Bull. 45 (2): 86.
Hernandez, M. 1988: Road mortality of the Little Owl (Athena noctua) in Spain. Journal of Raptor Research 22 (3): 81-84.
Heyder, R. 1954: Kreuzschnäbel als Salz- und Aschefresser. Beitr. Vogelk. 4: 1-7.
Heyder, R. 1960: Zur Aufnahme von Mineralsalzen durch Vögel. Beitr. Vogelk. 7: 1-6.
*Hilleghem, G. M. van 1965: Waarnemingen langs de Boudewijn-snelweg. De Wielewaal 31 (5): 133-137.
Hjorth, I. 1977: The territorial system of the Capercaillie (Tetrao urogallus) and the influence on the lek of environmental disturbances, especially with regards to forestry and highway traffic. Viltrapport 5: 73-77.
Hodson, N. L. 1960: A survey of vertebrate road mortality. Bird Study 7: 224-231.
Hodson, N. L. 1962: Some notes on the causes of bird casualties. Bird Study 9 (3): 168-173.
*Hodson, N. L. 1965: The road deaths enquiry 1960-1961. Bird Study 12: 90-98.
Hodson, N. L. 1966: Some notes on the habits of roadside carrion feeders. Bird Study 13: 272-273.
Hodson, N. L. & D. W. Snow 1965: The road deaths enquiry, 1960-61. Bird Study 12: 90-99.
*Höfels, R. 1971: Salzfressende Grünfinken (Chloris chloris). Ornith. Mitt. 23 (9): 178.
Holbrook, H. T. & M. R. Vaughan 1985: Influence of roads on Turkey mortality. J. Wildl. Managem. 49: 611-614.
Holisová, V. & R. Obrtel 1986: Vertebrate casualties on a Moravian Road. Acta Sc. Nat. Brno 20 (9): 1-44.
*Hope Jones, P. 1980: Bird scavengers on Orkney roads. British Birds 73: 561-568.
Hutton, K. & J. Brickhill, 1985.
Exceptional concentrations of barn owls
Tyto alba in the Riverina District of New South Wales. Australian
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Illner, H. 1988: Langfristiger Rückgang von Schleiereulen, Tyto alba, Waldohreulen, Asio otus, Steinkauz, Athene noctua und Waldkauz, Strix aluco in der Agrarlandschaft Mittelwestfalens 1974-1986. Die Vogelwelt 109: 145-151.
Illner, H. 1992: Road deaths of Westphalian owls: methodological problems, influence of road type and possible effects on population levels. UK Nat. Conserv. No. 5: 94-100.
Institut für Naturschutz und Tierökologie 1977: Tierwelt und Strasse. Problemübersicht und Planungshinweise. Jahrbuch für Naturschutz und Landschaftspflege 26: 91-115.
*Irisov, E.A. 1990: Gibel’ ptits na avtomobil’nykh dorogakh Altaiskogo kraya [The bird mortality on roads in Altai Krai (Territory)] Biotzenozy Altaiskogo kraya i vliyanie na nikh antropogennykh vozdeistviy. [Biocoenoses of Altai Territory and impact of anthropogenic influences on it]. Barnaul. P.88-90. In Russ.
Jackson, S. W. 1949: Highway fatalities among birds and animals. Highway Research Abstracts 19 (10): 18
Jennings, A. R. 1961: An analysis of 1000 deaths in wild birds. Bird Study Vol. 8 No. 1
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Johnson, P. N. 1989: Annual avian and mammalian traffic mortality along a South Yorkshire road. Naturalist (Leeds) 114 No. 990: 99-101.
Jones, L. 1927: Highway mortality and speed in flight. Wilson Bull. 39 (1): 8-10.
Jones, P. H.1980: Bird scavengers on Orkney roads. Brit. Birds 73: 561-568.
Jonkers, D. A. 1970: Nogmaals verkeersslachtoffers. Het Vogeljaar 12 (1): 23.
Jonkers, D. A. 1971: Warmte opname door oeverzwaluwen. Korhaan 5 (1): 10.
Jonkers, D. A. & G. W. de Vries 1977: Verkeersslachtoffers under de Fauna. Zeist. Nederlandse Vereningen tot Bescherming van Vogels, Zeist.
Joselyn, G. B., J. E. Warnock, & S. L. Etter 1969: Wildlife – an essential consideration determining future highway roadside maintenance policy. Highway Research Record 280. Pp. 14.
*Khokhlov, A.N. 1981: Gibel’ ptits na avtodorogakh [The bird mortality on roads]. Priroda [Nature], N9. P.51. In Russ.
*Khokhlov, A.N. 1991: Novye svedeniya o gibeli ptits na avtodorogakh Stavropol’ya [New data on bird loss on roads of the Stavropol’ Territory]. Aktual’nye voprosy ekologii i okhrany prirody Stavropol’skogo kraya i sopredel’nykh territoriy: Materialy nauch.-prakt. konf. [Actual problems of ecology and conservation of nature of the Stavropol’ Territory and adjoining territories: Materials of scient.-pract. Conf.]. Stavropol’:165-169. In Russian.
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*Klausnitzer, B. 1990. Ekologiya gorodskoi fauny [Ecology of the city fauna]. M.: 1-246. In Russian.
*Klees, A. A. H. 1976: Gevaarlijke t. v. masten en onkruidbermen. Het Vogeljaar 24 (1): 39.
Knierer, W. 1967: Untersuchungen über Tierverluste durch den Strassenverkehr. Z. Jagdwis. 13, H. 4: 159-164.
*Knutson, R. 1987: Flattened Fauna. A Field Guide to Common Animals of Roads, Streets and Highways. Ten Speed Press, Berkeley. This book is a joke!
*Knutsson, G., L. Bäckman, S. Hedgren, A. Rühling, & G. Tyler 1974: Vägars omgivande natur inverkan på– litteraturöversikt.- Statens Naturvårdsverk PM 476. Sweden.
Komarek, E. B. & E. G. Wright. 1929: Bird casualties on the highways. Wilson Bull. 41 (2): 106.
*Komarov, N.A., Komarov, Yu.Ye. 1991: Gibel’ ptits na antropogennykh objektakh Severnoi Osetii [The bird loss on anthropogenic objects of Northern Ossetia]. Fauna, naselenie i ekologiya ptits Severnogo Kavkaza [Fauna, population and ecology of birds of North Caucasia]. Stavropol’. Pp.18-19. Table 1. In Russ.
Korhonen, K. & L. Nurminen 1987: Traffic deaths of animals on the Kuopio-Siilinjarvi Highway in eastern Finland. Aquilo Ser. Zool. 25: 9-16.
*Kostecke, R. M., G. M. Linz, & W. J. Bleier, 2001: Survival of avian carcasses and photographic evidence of predators and scavengers. J. Field Ornithol. 72: 439-447.
*Kovalev, V.A. 1998: K gibeli ptits na avtomobil’nykh dorogakh [On the death of birds on roads]. Materialy III konferentsij molodykh ornitologiv Ukrajny [ Materials of the third conference of Young ornithologists of Ukraine]. Edited by V.N.Grishchenko. Chernivtsi. Library of the journal “Berkut”. Pp.70-71. Table 1. In Russian.
*Lalo, J. 1987: The problem of road kill. Amer. Forests (Sept-Oct): 50-52,72.
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*Laursen, K. 1981: Birds on roadside verges and the effect of moving on frequency and distribution. Biol. Conserv. 20: 59-68.
Lepschi, B. 1992: Bird killed on a primary road in southern New South Wales. Corella 16 (3): 75-77.
*Ligtenberg, G. & M. Wesselius, 1971: Verkeersslachtoffers in Arnhem. Het Vogeljaar 19 (3): 522.
Lincoln, F. C. 1931: Some causes of mortality among birds. Auk 48 (4): 538-546.
*Lidauer,, R. 1983: Knockenfrakturen bei Stadtamseln (Turdus merula). Ökol. Vögel 5: 111-126.
Linsdale, J. M. 1929: Roadways as they affect bird life. Condor 31 (4): 143-145.
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*Löhr, H. 1950: Vögel als Verkehrsopfer. Berichte der Staatlichen Vogelschutzwarte Ludwigsburg 1949: 132-136.
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Lüpke, M. 1983: Vogelverluste an einer Fernverkehrsstrasse. Falke 30 (2): 58-60.
*Luttringer, L. A. Jr. 1927: Many valuable birds killed yearly in Pennsylvania by carmobiles. Oölogist 44 (8): 111-112.
*Maarel, E. v. d. 1972: De invloed van het zich ontwikkelende hoofdwegennet op natuur en landschap. Stedebouw en Volkshuisvesting 53: 3-18.
McClure, H. E. 1951: An analysis of animal victims on Nebraska’s highways. J. Wildl. Management 15: 410-420.
*McCulloch, E. M. 1971: Hirundine road casualties. Canberra Bird Notes 13: 2-3.
*MacNamara, L. G. 1962: Survey of car-killed wildlife. New Jersey Outdoors 13 (4): 23.
*Mader, H. J. 1984: Animal habitat isolation by roads and agricultural fields. Biol. Conserv. 29: 81-96.
Madsen, A. B., H. W. Fyhn, & A. Prang, 1998: Trafikdræbte dyr i landskabsøkologisk planlægning og forskning. Danmarks Miljøundersøgelser. Faglig rapport fra DMU, nr. 228. Pp. 42.
*Mankinov, D, N. & N. M. Todorov. 1983: Bird casualties on highways. Sov. J. Ecol. 14: 288-293.
Martens, J. 1962: Gefährdung der Vogelwelt durch Kraftwagen. Orn. Mitt. 14: 221.
*Martens J. 1978: Gefährdung der Vogelwelt durch Kraftwagen. Orn. Mitt. 14: 221-222.
*Martin R. J. 1939: Highway toll. Mich. Cons. 9: 2.
*Martinez-Abrain, A. 1994: Mortalidad estacional de aves en una carretera del P. N. de L’Albufera de Valencia (E. Espana). Donana Acta vertebr. 21: 90-95
Mason, C. & S. MacDonald, 1995: Corvids feeding on carrion. Bird Study 42: 255-256.
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*Massemin, S. & T. Zorn, 1998. Highway mortality of barn owls in northeastern France. Journal of Raptor Research 32:229-232.
Meade, G. M. 1942: Calcium chloride – a death lure for crossbills. Auk 59: 439-440.
Meinertzhagen, R. 1954: Grit. Bull. Brit. Orn. Club 74: 97-102.
Mendelsohn, J. 1983. Causes of mortality in black-shouldered kites. Bokmakierie 35:11-13.
Miech, P. 1988: Wirbeltierverluste auf einer Waldstrasse im Spandauer Forst. Berl. Nat.schutzbl. 32: 125-135.
*Mörzer Bruyns, M. F. 1959: Faunasterfte door verkeer. De Levende Natuur 62 (4): 73-77.
Mounts, B. T. 1927: Some observations made in Florida and enroute to Iowa. Wilson Bull. 39 (4): 235.
Müller, A. 1995: Vogelverluste durch den Straßenverkehr in Abhängigkeit von der Jahreszeit. Beitr. Gefiederkunde und Morphologie der Vögel 2: 47-54.
Müller-Using, D. 1956: Ist die Nachtschwalbe (Caprimulgus europaeus) durch die zunehmende Motorisierung besonders gefährdet? Orn. Mitt. 8 (1)
Nankinov, D. N. & N. M. Todorov 1983: Bird casualties on highways. Sov. J. Ecol. 14: 288-293.
*Neff, J. A. 1926: Carmobile toll on the Oregon highway. Oölogist 43 (4): 55-59.
Nero, R. W. & H. W. R. Copland 1981: High mortality of Great Gray Owls in Monitoba – winter 1980-81. Blue Jay 39 (3): 158-165.
Nicolai, B. 1994. [Common hamster,
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*Novak, V.O. 1995.:Zagybel’ ptakhiv na avtoshlyakhakh Podillya [The birds death on the main roads of Podolia]. Problemi vyvchennya ta okhorony ptakhiv [Problems of study and protection of birds.] Materials of the VI conference of Western Ukraine Ornithologists (Drohobych, 1-3 February, 1995). Lviv-Chernivtsi. Pp.99-100. In Ukrainian.
*Novelli, R., E. Takase, & V. Castro. 1988: Study of birds killed by collision with vehicles in a stretch of highway BR-471 between Quinta and Tam Rio Grande do Sul, Brazil. Rev. Bras. Zool. 5 (3): 441-454.
*Obrtel, R. & V. Holi]ová: 1986: Vertebrate casualties on a Moravian road. Acta Science Nat. Brno 20 (9):1-44.
*Odzuck, W. 1975: Im bayerischen Alpenvorland durch den Straßenverkehr getötete Wirbeltiere. Natur und Mensch 17 (3): 153-158.
Oeser, R. 1977: Der Fichtenkreuzschnabel (Loxia curvirostra L.) als Opfer des Straßenverkehrs im Fichtenberggebiet. Beitr. Vogelkd. 23: 278-280.
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*Olsson, L. 1974: Trafikdöden i Djurvärlden. Rapport till Statens Naturvårdsverk, Sweden.
**Osieck, E. 1973: Groot aantal Kepen (Fringilla montifringilla L.) slachtoffer van het verkeer in winter 1970-1971. Het Vogeljaar 21 (1): 274.
*Paruk, J. D. 1990: Effects of roadside management practices. On bird richness and reproduction. Transac. Illinois State Acad. Sci. 83 (3-4): 181-192.
*Pearce, F. 1992: The deadlist roads in Europe. New Scientist 24 Oct: 23-24.
Plumpton, D. & R. Lutz, 1993: Influence of vehicular traffic on time budgets of nestling Burrowing Owls. J. Wildlife Management 57: 612-616.
Przybylski, Z. 1979: The effect of carmobile exhaust gases on the arthropods of cultivated plants, meadows and orchards. Environmental Pollution 19: 157-161.
Quadrelli, G. 1984: Il traffico stradale come causa di morte per gli uccelli in un’area della pianura padana. Riv. Ital. Orn. Milano 54 (1-2): 77-80.
*Quene, E. & J. Grotenhuis, 1994: Vogelslachtoffers op de Drentse wegen – een vervolg. Drentse Vogels 7: 73-81. (Dutch with English summary)
Pickles, W. 1942: Animal mortality on three miles of Yorkshire roads. J. Animal Ecology 11: 37-43.
Räty, M. 1979: Effect of highway traffic on tetraonid densities. Ornis Finnica 56: 169-170.
*Reijnen, M. J. S. M. & J. B. M. Thiessen 1987: Effects from road traffic on breeding bird populations in woodland. Annual Report 1986: 121-132.
Reijnen, M. J. S. M., J. B. M. Thissen, & G. J. Becker. 1987: Effects of road traffic on woodland breeding bird populations. Acta Oecologica Generalis 8: 312-313.
Reijnen, R. & R. Foppen 1991: Effect of road traffic on the breeding site-tenacity of male Willow Warblers (Phylloscopus trochilus). J. Orn. 132: 291-195.
*Reijnen, R. & R. Foppen 1994: The effect of car traffic on breeding bird populations in woodland. I. Evidence of reduced habitat quality for Willow Warblers (Phylloscopus trochilus) breeding close to a highway. J. Applied Ecology 31: 85-94.
Reijnen, R., R. Foppen, C. T. Braak, & J. Thissen 1995: The effects of car traffic on breeding bird populations in woodland. III Reduction of density in relation to the proximity of main roads. J. Appl. Ecol. 32: 18
*Reinhold, J. 1987: [Traffic victims. Review of methods of road kill studies] Amoeba 1987 (3): 21-23. (In Dutch).
Rettig, K. 1965: Tierverluste auf Autostrassen. Orn. Mitt. 17 (11): 233-234.
Robertson, McB, J. 1930: Roads and birds. Condor 32 (3): 142-146.
*Rogovyi, Yu.F. 1998: Zagybel’ ptakhiv na avtoshlyakhakh Globins’kogo raionu Poltavs’koi oblasti [On the death of birds on roads]. Materialy III konferentsij molodykh ornitologiv Ukrajny [Materials of the third conference of Young ornithologists of Ukraine]. Edited by V.N.Grishchenko. Chernivtsi. Library of the journal “Berkut”. Pp.123-126. Table 2. In Ukrainian.
Russel, H. N. & D. Amadon 1938: A note on highway mortality. Wilson Bull. 50: 205-206.
*Sal’nikov, G.M., & S. V. Buslaev, 1986: Gibel’ ptits na avtomobil’nykh dorogakh v Ivanovskoi oblasti .[The birds mortality on roads of Ivanovo Region]. Izuchenie ptits SSSR, ikh okhrana i ratsional’noe ispol’zovanie [Study of birds of the USSR, their conservation and wise management]. Leningrad (now-St.-Petersburg). Part 2. P.222-223. In Russ.
Sargeant, A. B. & J. E. Forbes 1973: Mortality among birds, mammals and certain snakes on 17 miles of Minnesota roads. Loon 45 (1): 4-7.
*Sauerland, K. E. 1969: Wirbeltierverluste an Landstrassen. Naturschutzarbeit in Mecklenburg 1.
Schoenemann, W. 1977: Wildunfälle im Strassenverkehr. Zool. Beiträge 23 (2): 169-219.
*Schorger, A. W. 1954: A study of road kills. Passenger Pigeon 16: 53-55.
Scott, T. G. 1938: Wildlife mortality on Iowa’s highways. Am. Midland Nat. 20 (3): 527-539.
*Seeker, B. 1960: Roadside vegetation control and the public. 19 short Course on Roadside Development, Ohio State Univ. & Ohio Dept. of Highway. Pp. 87-91.
Seibert, H. C. & J. H. Conover. 1991: Mortality of Vertebrates and Invertebrates on an Athens County, Ohio Highway. Ohio Journal of Science 91 (4): 163-166.
Seifert, S. 1960: Nächtlige Rast vom Ziegenmelkern. Beitr. Vogelkunde, Band 7: 23.
Sharma, S. K. 1988: Bird casualties in road accidents. J. Bombay Nat. Hist. Soc. 85: 195-197
Sharp, H. S. 1930: Red-headed Woodpeckers and carmobiles. Bird Lore 32 (5): 352.
*Shchitova, E.G. 1981: Vliyanie avtomobil’nogo transporta na faunu okrestnostei Pushchina [Influence of car roads on the fauna of Pushchino vicinities]. Ekologiya malogo goroda [Ecology of small town]. Pushchino. P.118-125. In Russ.
Shchitova, E.G. 1982: Metodika ucheta zhivotnykh, pogibshchikh na avtomobil’nykh dorogakh [Methods of the count of animals, died on car roads]. Pushchino. 10 pp. In Russ.
Short, H. L. & D. E. Craigie, 1958: Pied-billed Grebes mistake highway for Water, Auk 75 (4): 473-474.
Siegfried, W. R. 1965: A survey of wildlife mortality on roads in the Cape Province. Prov. Admin. Cape of Good Hope, Dept. of Nat. Cons. Invest. Rep. 6.
Skriver, J. 2001: Naturens take away. Bilisten marts (1): 50-52. (In Danish).
Slater, F. 1994: Wildlife road casualties. British Wildlife 5: 214-221.
Slater, P. 1997: Hungry eagles a traffic hazard. West Australian Ornithologist January issue.
Smettan, H. W. 1988: Wirbeltiere und Strassenverkehr – ein ökologischer Beitrag zum Strassentod von Säugern und Vögeln am Beispiel von Ostfildern/Württemberg. Ornithologische Jahreshefte für Baden-Württemberg 4 (1): 29.55.
*Smislovs, V. & A. Kurockins, 1994: Bird mortality on roads in
Spiker, C. J. 1927: Feathered victims of the carmobile. Wilson Bull. 39: 11.
Stanford, J. K. 1954: Nightjars sitting on roads at night. Ibis 96: 316.
Starrett, W. C. 1938: Highway casualties in Central Illinois during 1937. Wilson Bull. 50 (3):193-196.
Stephens, T. C. 1928: Editorial. [Red-headed Woodpeckers killed by motor cars]. Wilson Bull. 40 (3): 192.
Stevens, O. A. 1932: Bank Swallows killed by carmobiles. Wilson Bull. 44 (1): 39.
Stewart, P. A. 1971: Persistence of remains of birds killed on motor highways. Wilson Bull. 83 (2): 203-204.
Stoner, D. 1925: The toll of the carmobile. Science 61 (1568): 56-57.
*Stoner, D. 1929: Speeding motor cars take toll of wild life. U. S. Dept. Agric. Clip Sheet No. 563: 2.
*Stoner, D. 1936: Studies on the Bank Swallow Riparia riparia riparia (Linnaeus) in the Oneida Lake Region. Rosevelt Wild Life Annals 4 (2): 122-233.
Stoner, D. 1936: Wildlife casualties on the highways Wilson Bulletin 48: 276-283.
Summers-Smith, D. 1956: Mortality of the House Sparrow. Bird Study 3: 265-270 (Not about traffic accidents)
Sutton, G. M. 1927a: Mortality among Screech Owls of Pennsylvania. Auk 44: 563-564.
Sutton, G. M. 1927b: Snowy Owl killed by carmobile. Auk 44 (4): 564.
*Taapken, J. 1955: Catastrophale sterfte van Apus apus (l), Hirundo rustica (l) en Delichon urbica (l) gedurende de periode van eind mei mei mei tot begin juni 1953, veroorzaakt door abnormaal lage temperaturen en voedselgebrek. Ardea 43 (4): 275-283.
Tabor, R. 1974: Earthworms, crows, vibrations and motorways. New Scientist 62 (899): 482-483.
Taylor, R. J. & N. J. Mooney, 1991: Increased mortality of birds on an elevated section of highway in Northern Tasmania. Emu 91: 186-188.
Tepper, M. 1964: Zur Gefährdung der Vogelwelt durch Kraftwagen. Orn. Mitt. 16 (1)
Thiel, R. P. 1980: Unusual vehicle caused mortality in Red Crossbills. Passenger Pigeon 41 (1): 23-24.
*Thomas, E. 1988: Road deaths. Bird Observation No. 678: 94.
Thomsen, K. 1992: Project Vildtregistrering. Rapport for Falck Danmark. Pp. 33.
*Timofeev, A.N., & V. A. Tel’pov, 1991: Zametki o gibeli ptits na Stavropolie [Remarks on bird mortality in Stavropol’ territory]. Rasprostranenie, chislennost’ i biologiya ptits Severnogo Kavkaza [Distribution, number and biology of birds of Northern Caucasia]. Pp.108-109. In Russ.
Tischner, K. 1979: Road kills of South Jersey. Cassinia No. 57: 22-24.
*Tönnier, G. 1960: Wildverluste an der Landstrasse. Schleswich-Holsteinischen Bauernblatt 27.8.1960.
Uhlenhaut, K. 1976: Unfalle von Schleiereulen durch Kraftfahrzeuge. Falke 21: 56-60.
*van der Zande A. N., W. J. Terkeurs, & W. J. van der Weijden 1980: The impact of roads on the densities of four bird species in an open field habitat-evidence of a long distance effect. Biol. Conservation 18: 299-321.
Verbelen, F. 1993: Observation of a major ‘fall’ of migrating Hooded Pittas (Pitta sordida) at Kaeng Krachan National Park, Phetchaburi Province. Nat. Hist. Bull. Siam Soc. 41: 121.
*Vermeer, K. & B. Switzer, 1968: Road kills of birds and mammals in southeastern Alberta. Blue Jay 26 (2): 93-94.
Vestjens, W. J. M. 1973: Wildlife mortality on a road in New South Wales. Emu 73: 107-112.
Vignes, J. C. 1984: Les oiseaux victimes de la circulation routière au Pays basque francais. Oiseau 54 (2): 137-148.
*Vladyshevskiy, D.V. 1975. Ptitsy v antropogennom landshafte [Birds in anthropogenic landscape]. Novosibirsk, Nauka. 200 pp. In Russ.
*Voous, K. H. 1960: De kievitensterfte in de droge zomer van 1959. Het Vogeljaar 8 (6): 123.
Ward, W. B. 1934: Owls on a Lousiana highway. Auk 51 (2): 236.
Warren, E. R. 1936: Casualties among animals on mountain roads. Science 83 3 January, (2140): 14.
Warren, E. R. 1936: Mountain road casualties among animals in Colorado. Science 84 27 November, (2187): 485.
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*Zimmerman, D. A. 1954: Bird mortality on Michigan highways. Jack Pine Warbler 32 (2): 60-66.
Zumeta & Holmes 1978: Habitat shift and roadside mortality of Scarlet Tanagers during a cold wet New England spring. Wilson Bull. 90 (4): 575-586.
|
|
|||||||||||||||
|
J |
F |
M |
A |
M |
J |
J |
A |
S |
O |
N |
D |
||||
|
House Sp. |
Germany |
2 |
2 |
4 |
5 |
10 |
12 |
35 |
44 |
22 |
5 |
1 |
2 |
1974-1977 |
Blümel & Blümel 1980 |
|
House Sp. |
Denmark |
12 |
19 |
65 |
70 |
78 |
174 |
89 |
53 |
1957-1965 |
Hansen 1982 |
||||
|
House Sp. |
Denmark |
16 |
41 |
83 |
115 |
154 |
330 |
467 |
116 |
1979-1981 |
Hansen 1982 |
||||
|
Tree Sp. |
Denmark |
3 |
5 |
11 |
15 |
19 |
32 |
24 |
19 |
1957-1965 |
Hansen 1982 |
||||
|
Tree Sp. |
Denmark |
4 |
11 |
21 |
22 |
24 |
71 |
72 |
17 |
1979-1981 |
Hansen 1982 |
||||
|
House Sp. |
Sweden |
17 |
5 |
1 |
11 |
35 |
100 |
25 |
3 |
1973-1976 |
Göransson et al. 1978 |
||||
|
Tree Sp. |
Sweden |
1 |
2 |
5 |
13 |
7 |
5 |
1973-1976 |
Göransson et al. 1978 |
||||||
|
House Sp. |
England |
2 |
0 |
7 |
5 |
9 |
52 |
124 |
49 |
21 |
12 |
1 |
1 |
1957-1960 |
Dunthorn & Errington 1964 |
|
House Sp. |
England |
23 |
47 |
119 |
150 |
400 |
383 |
472 |
478 |
175 |
75 |
26 |
17 |
1960-1961 |
Hodson & Snow 1965 |
|
|
||||||
|
Country |
dist. travelled |
year |
transport |
number killed |
Average |
Source |
|
Australia |
14.440km |
70-72 |
car |
1.095 |
13km |
Vestjens 1973 |
|
Australia |
496km |
77-78 |
car |
56 |
33km |
Disney & Fullagaer 1978 |
|
Australia |
3.395km |
88-90 |
car |
265 |
13km |
Lepschi 1992 |
|
Austria-Yogo.-Greece |
4.510km |
60 |
car |
210 |
21km |
Haas 1964 |
|
Denmark |
8.075km |
57-65 |
moped |
2.172 |
4km |
Hansen 1982 |
|
Denmark |
15.224km |
79-81 |
moped |
5.144 |
3km* |
Hansen 1982 |
|
England |
16.111km |
34-37 |
car |
1.885 |
12km |
Breadnell 1937 |
|
England |
6436km |
35 |
bicycle |
940 |
7km |
Barnes 1936 |
|
England |
619km |
Jan-Mar55 |
bicycle |
9 |
69km |
Finnis 1960 |
|
England |
619km |
May-Jun 55 |
bicycle |
61 |
10km |
Finnis 1960 |
|
England |
788km |
Sep-Dec 55 |
bicycle |
8 |
99km |
Finnis 1960 |
|
England |
134km |
56 |
car |
55 |
2km |
Harrison in: Finnis 1960 |
|
England |
c.4.518km |
57 |
bicycle |
415 |
11km |
Dunthorn in: Finnis 1960 |
|
England |
c. 805km |
Aug-Sep 57 |
walking |
30 |
27km |
Jones in: Finnis 1960 |
|
England |
c. 282km |
1-14 Aug 58 |
walking |
14 |
20km |
Jones in: Finnis 1960 |
|
Finland |
32.250km |
82-84 |
car |
116 |
278km |
Jones in: Finnis 1960 |
|
N Finland + N Norway |
3.403km |
61 |
car |
23 |
148km |
Haas 1964 |
|
France |
3.623km |
56 |
car |
4 |
905km |
Harrison in Finnis 1960 |
|
Germany |
1.030km |
76-77 |
bicycle |
375 |
3km |
Günther 1979 |
|
Marocco |
2.589km |
59 |
car |
67 |
39km |
Haas 1964 |
|
South Africa |
30.803km |
60-62 |
car |
343 |
90km |
Broekhuysen 1965 |
|
Spain |
1.900km |
56 |
bicycle |
68 |
28km |
Haas 1964 |
|
Spain |
1.900km |
60 |
bicycle |
183 |
10km |
Haas 1964 |
|
Spain |
2.200km |
62 |
car |
37 |
59km |
Haas 1964 |
|
Sweden |
1.774 |
61 |
car |
83 |
21km |
Haas 1964 |
|
Sweden |
5.290km |
74-76 |
car |
742 |
7km |
Göransson et al. 1978 |
|
Switzerland-France |
2.474km |
62 |
car |
56 |
44km |
Haas 1964 |
|
Texas |
1.768km |
75-76 |
car |
49 |
36km |
Wilkins & Schm |
|
USA |
508km |
24 |
car |
142 |
4km |
Stoner 1925 |
|
USA |
481km |
25 |
car |
134 |
4km |
Flint 1926 |
|
USA |
17.700km |
26 |
car |
106 |
167km |
Jones 1927 |
|
USA |
4.000km |
26 |
car |
2 |
2.000km |
White 1927 |
|
USA |
5.632km |
26 |
bicycle |
277 |
20km |
Spiker 1927 |
|
USA |
14.006km |
27 |
? |
136 |
103km |
Robertson 1930 |
|
USA |
26.870km |
27-29 |
car |
353 |
76km |
Baumgartner 1934 |
|
USA |
35.000km |
27-29 |
car |
9 |
3.889km |
White 1929 |
|
USA |
579km |
28 |
car |
34 |
17km |
Komarek 1929 |
|
USA |
418km |
28 |
car |
18 |
23km |
Komarek 1929 |
|
USA |
800km |
33 |
car |
69 |
12km |
Davis 1934 |
|
USA |
78.052km |
32-50 |
car |
4.039 |
19km |
Schorger in Finnis 1960 |
|
USA |
8.858km |
34-36 |
car |
22 |
402km |
Dickerson 1939 |
|
USA |
10.917km |
34-36 |
car |
84 |
129km |
Dickerson 1939 |
|
USA |
3.532km |
38 |
car |
548 |
6km |
Russell 1938 |
|
USA |
12.114km |
38 |
car |
607 |
20km |
Starrett 1938 |
|
USA |
80km |
87-88 |
walking |
21 |
4km |
Seibert & Conover 1991 |
|
* In the last study the winter months were not examined. |
||||||
Recommended Citation.
Erritzoe, J. 2002: Bird Traffic casualties and road quality for breeding
birds. A summary of existing papers with a bibliography.
www.birdresearch.dk