By the early 1990s, just 10 pink pigeons remained in Mauritius; captive breeding helped the wild population recover to 400 to 480 birds

An endangered bird in Mauritius has made a gradual recovery through decades of conservation work, but rising numbers have not eliminated the risks to its long-term survival. By about 1990, the wild pink pigeon population had dwindled to roughly 10 birds amid habitat loss, fragmentation and pressure from introduced species. Captive breeding and releases helped rebuild the population to several hundred birds, although concerns remain about the genetic diversity needed to sustain that recovery.

A 2022 study published in Conservation Biology examined the genetic consequences of the pink pigeon's population collapse and subsequent recovery. The findings showed that genetic diversity continued to decline despite the increase in numbers. The research highlights why population size alone cannot establish whether a threatened species is secure and why conservation programs must also protect the genetic variation needed for long-term survival.

The pink pigeon ( Nesoenas mayeri ) is native to Mauritius. Its numbers fell over decades as natural habitats were destroyed or fragmented and introduced species added pressure on the remaining population. To prevent extinction, conservationists established a captive breeding program and used its birds to reinforce wild populations.

Between 1976 and 1981, conservationists took 12 pigeons from the last known wild population at Pigeon Wood to establish a breeding group at the Gerald Durrell Endemic Wildlife Sanctuary in Mauritius. The wild population continued to face severe pressures in subsequent years, reaching an estimated low of about 10 birds by the early 1990s. Managed breeding and releases later helped establish and strengthen wild subpopulations.

Researchers analyzed genetic data from wild pigeons alongside breeding records covering 1,112 birds held in zoos across Europe and the United States. Using DNA sequencing, genetic markers, and computer simulations, they investigated how the species' genetic makeup changed during its collapse and recovery.

By 2013, the free-living population had grown to around 400 birds, according to the research. The broader recovery brought the population to an estimated 400 to 480 birds, and the species was subsequently reclassified on the International Union for Conservation of Nature's Red List, moving from Critically Endangered to Vulnerable through two status changes. These improvements reflected a meaningful conservation achievement, but they did not remove the genetic risks created by the earlier population collapse.

Despite the numerical recovery, genetic diversity continued to decline. In small populations, inbreeding becomes more likely because individuals have fewer potential mates, while genetic drift can randomly eliminate inherited variation. These processes can reduce a population's ability to adapt to environmental changes and increase the likelihood that harmful genetic variants will affect reproduction and survival.

The researchers estimated that the pink pigeon's effective population size, which measures how many individuals contribute genetically to future generations, was roughly one-tenth of its recorded population size.