The ecology and conservation of the pink pigeon Columba Mayeri in Mauritius

The pink pigeon Columba mayeri was a critically endangered endemic bird from Mauritius= in the Indian Ocean. The species reached its lowest point of between 10 and 20 birds in 1975 and the wild population continued to decline to 9 or 10 birds in 1990. The causes of decline included habitat destruction, seasonal food shortages and predation by introduced mammals. Between 1987 and 1997, 256 captive-reared birds were released on Mauritius at three sites. Free-living birds were intensively managed and between 1988 and 1998, 429 young fledged in the wild. The population numbered 297 birds at the end of 1998. Factors limiting survival and reproductive success were identified and an assessment of the re-introduction programme made. Mean survival of j'Qveniles (up to one year old) was 68% and adults 83% per year. Median age at egg-laying for females was 10.9 months and fertility 58.6%. Mean annual nest success was 18.4% and productivity 1.2 young per female from 1992. Productivity for males and females peaked in year one and there was large individual variation, 9% of females produced 43% of young. Survival, nest success and productivity varied between sites, were affected by inbreeding and were poorer for released birds than wild-fledged birds. Causes of nesting failure included predation, infertility and disease. Unhatched eggs accounted for 56% of failed nests in a predator-free environment. Disease affected survival of fledged birds and squabs. On lIe aux Aigrettes trichomoniasis affected 49% of squabs. About 10% of all birds suffered from avian pox and 36% of all birds were infected with Leucocytozoon marchouxi. As a result of the programme, the pink pigeon has been down-listed to endangered. With management, survival and productivity are sufficient to contribute to population growth. This programme was considered a good example of the interface between captive-breeding and the recovery of a wild population.