Habitat protection and/or captive breeding? That's the question.
Many initiatives to save Gurney's Pitta Pitta gurneyi have been launched, as readers of this journal well know.In the last issue, Chris Gooddie described his London Marathon run to raise money. In the same issue it was reported that continued destruction of the pitta's remaining lowland forest habitat and disturbance by visiting 'listers' who fail to follow the simple guidelines of good behaviour are the biggest threats for the remaining few birds. 1
The potential of captive breeding as an aid in avian conservation is often considered questionable and usualy considered only as a last resort. However, IUCN recommend establishing a captive population when the wild population falls below 1,000 individuals2. A recent survey concluded that about 12 pairs of Gurney's Pitta now remain in the wild and BirdLife Internationa13 presents a still more pessimistic assessment of 18 individuals. With so few individuals one must realise that the bird is on the brink of extinction, that previous efforts have been unsuccessful and that emergency measures are now required.
The following proposals are taken from the literature, but modified to take into account the particular situation that Gurney' s Pitta is in. I feel they should be given serious consideration:
1. Removing eggs from a few nests, artificially rearing them, and releasing the fledglings as soon as they are self-supporting.
2. Doing the same, but with only the weakest chick from each nest, as its chance of survival in the wild is small anyway.
3. Cross-fostering eggs and young to another species to boost productivity.
4. Letting zoos with the necessary expertise and facilities take over.
5. Attempting to establish whether nest predation is a serious problem using video surveillance and subsequently implementing control measures.
As for the first two options, and particularly the third. these would be verv cheap and carry a reasonable chance of success. Experiences at the Walsrode Vogelpark in Germany indicate that young Banded Pittas Pitta guajana are rather easy to hand-rear and later can be housed peacefully with adult conspecifics (Simon Bruslund Jensen in litt.). Although both Hooded P. sordida and Blue- winged Pittas P. moluccensis are common in Khao Nor Chuchi, the Gurney's nearest relative, the Banded Pitta is rare,4 but perhaps these other species could be used as fosterers. It should be noted that wild Gurney's Pittas will very likely lay a replacement clutch following removal. The third method was used with great success to save the Chatham Robin Petroica traversi from extinction with the help of the common Chatham Island Tit. The population now stands at 259 birds.3,5
Captive breeding of Mauritius Kestrel Falco punctatus, Mauritius Pigeon Columba mayeri and Mauritius Parakeet Psittacula echo resulted in a better understanding of our responsibility to save natural resources. Implementation of captive breeding by zoo staff with appropriate expertise (option four) led directly to the development of a National Park in Mauritius, and habitat improvement on Round Island and Ile aux Aigrettes.3,6,7 Moreover, zoos would probably get involved and meet most cost themselves, because Gurney' s Pitta is a very beautiful and charismatic bird with much publicity value and modern zoos have vast experience in fund raising, finding donors and lobbying local politicians for support.2,8 In 1998 there were about 14 Bali Mynas Leucopsar rothschildi in the wild, but at the same time more than 700 in captivity,9 while at present there are regrettably only a few confiscated Gurney's Pittas in Thai zoos. The California Condor Gymnogyps californianus 10 the Northem Bald Ibis Geronticus eremita 11, and the Socorro Dove Zenaida graysoni 3 are all pertinent examples here.
The Echo Parakeet and the Pink Pigeon were both successfully saved by identifying and controlling nest predators.7
The danger of inbreeding depression is of course something that has to be taken into account. However, there are many examples of recovery from very constricting bottlenecks: consider the Mauritius Kestrel (six individuals, of which two didn’t breed), and the Chatham Robin (one breeding pair), both of which recovered successfully. With so few remaining wild Gurney's Pittas, they are already going through a severe genetic bottleneck.
It has long been known that pittas can be bred easily in captivity.12 For success it is necessary to have large aviaries with high humidity and dense vegetation and bathing facilities. In recent years many aviaries, especially in zoos, have successfully bred several species of pitta. 13
The dialogue with the Thai Government has clearly not been a success. There are many and varied pressures on land use, and saving a few remaining individuals of a rare bird seems only a minor concern. Let us recognise this and act before it is too late. Gurney's Pitta may well be the next species to become extinct. We have to decide whether having a species in captivity is better than not having it at all.
Reterences
1. Sykes, B. (2001) Gurney's Pitta campaign update. OBC Bull. 33: 17-19.
2. Foose, T. J., de Boer, L., Seal, U. S., and Lande, R. (1995) Conservation Management. Strategies Based on Viable Populations. New York: Columbia University Press.
3. BirdLife International, (2000) Threatened Birds of the World. Barcelona and Cambridge: Lynx Edicions and BirdLife International.
4. Round, P. D. and Treesucon, U. (1996) Birds of Khao Nor Chuchi. Bird Conservation Society of Thailand and Khao Nor Chuchi Lowland Forest Project.
5. Butler, D. and Merton, D. (1992) The Black Robin. Saving the World's Most Endangered Bird. Auckland: Oxford University Press.
6. Collar, N. J., Crosby, M. J. and Stattersfield, A.J. (1994) Birds to Watch 2. Cambridge: BirdLife International.
7. Fa, J. E., Clark, C. C. M. and Hicks, S. D. J. (1995) Training in Zoo bio1ogy at the Jersey Wildlife Preservation Trust: a retrospective look and a glance at the future. Dodo, J. Wildl. Preserv. Trusts 31: 28-40.
8. Feistner, A. T. C. (1993) The sixth world conference on breeding endangered species: the role of zoos in global conservation. Dodo, J. Wildl. Preserv. Trusts 29: 8-22.
9. Anon. (1998) Only 14 Bali Starlings survive in the world! World Birdwatch 20 (1): 4.
10. Snyder, N. and Snyder, H. (2000) The California Condor. London: Academic Press.
11. Bowden, C. (1998) Last chance for the Northem Bald Ibis. World Birdwatch 20 (2): 12-16.
12. Delacour, J. (1934) The first rearing of pittas in captivity. Pp 717-719. In: Stresemann, E. ed. Proceedings Eighth International Ornithological Congress. Oxford.
13. Erritzoe,J. and Erritzoe, H. (1998) Pittas ofthe World. Lutterworth, Cambridge.