Back in the 1980s there were just ten or so pink pigeons left in the wild. Known to scientists as Nesoenas mayeri, the species is found only on Mauritius, the Indian Ocean island that was once home to the dodo. Like the dodo, the pink pigeon made an easy target for cats, rats and other predators introduced by humans, who also chopped down almost all of their native forest. Unlike the dodo, however, the pink pigeon has since made a remarkable recovery.

Fortunately, the Mauritian Wildlife Foundation had already taken 12 birds from the wild in the 1970s and 80s to establish a captive population. The offspring of these birds were then released during the 1990s and early 2000s and there are now at least 400 living in the wild. The species has even been officially down-listed twice, from “critically endangered” to “vulnerable”.

However, such a severe population bottleneck can lead to significant “genomic erosion”, where a species becomes less genetically healthy as so many animals are closely related. To examine the exact impact, we worked with a team of scientists to sequence the DNA of 175 birds sampled between 1993 to 2010 during the period of population recovery. Our results are now published in the journal Conservation Biology. Disappointingly, we found that the species continued to lose genetic diversity even as overall numbers increased during the successful conservation rescue programme. We speculated that the bottleneck must have changed something in the pink pigeon’s DNA.

Two pigeons in a nest
Today pink pigeons are mostly found in one small forest in south western Mauritius. Carl Jones, Author provided
To understand what caused this continued genetic erosion, we looked at data on 1,112 pink pigeons in European and US zoos. This data had been collected over four decades, and included each bird’s level of reproductive success and longevity together with levels of inbreeding calculated using pedigrees. Based on the relationship between these factors, we found the species carried a worryingly high “genetic load”.

Read more - https://theconversation.com/pink-pigeons-in-mauritius-made-a-remarkable-comeback-from-near-extinction-but-are-still-losing-genetic-diversity-179521