Reintroduction of the critically endangered Mauritius fody to Ile Aux Aigrettes, Mauritius

Summary

The Mauritius fody (Foudia rubra), a small endemic passerine classified as Critically Endangered in 2002, had declined across Mauritius mainly due to nest predation by introduced rats, feral cats and crab-eating macaques. The Mauritian Wildlife Foundation targeted Ile aux Aigrettes (IAA), a 25-hectare islet 660 m offshore with restored native forest and no mammalian predators, to establish a second, self-sustaining subpopulation. Starting in 2001, pairs on the mainland were monitored, and from 2002 chicks and eggs were harvested from wild nests at Pigeon Wood in Black River Gorges National Park for hand-rearing at the Gerald Durrell Endemic Wildlife Sanctuary, alongside a captive-breeding program using four hand-reared pairs; in total 52 chicks and 21 eggs were harvested from the wild and 32 fledglings were produced in captivity. Over three years, 93 juveniles and captive-bred adults were soft-released on IAA, held in an aviary for 7-12 days to habituate before release, with hand-rearing and captive breeding halted in 2006 once wild breeding on the island succeeded for two consecutive seasons. All birds were ringed and closely monitored for survival, breeding, territoriality and diet; by 2017 the population had grown to 258 confirmed birds plus 87 recently seen, an estimated 345 total, with fodies shown to be more adaptable and more polygamous than mainland populations, and naturally-resolving pox outbreaks caught through monitoring. As a result, the species was downlisted from Critically Endangered to Endangered in 2009. The project rates itself successful, citing a clear unchanging vision, sound preliminary research, a strong founder cohort, the species' natural adaptability, and dedicated staff and volunteers.