Letters

Extinct-in-the-wild species' last stand

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Science  31 Jul 2020:
Vol. 369, Issue 6503, pp. 516
DOI: 10.1126/science.abd4560

The lockdowns and closures enacted in response to the coronavirus disease 2019 (COVID-19) pandemic have led to massive income losses for zoos, aquariums, and botanical gardens worldwide (14). Insufficient funding could affect the ability of these institutions to support wildlife conservation, which could lead to extinctions. There are currently at least 77 species of plants and animals that are extinct in the wild and exist only in zoological and botanical collections, where they rely on human care for survival (5).

Most extinct-in-the-wild species exist in small, closed populations, vulnerable to stochastic demographic processes and genetic threats associated with inbreeding (6, 7). For example, the sihek (Todiramphus cinnamominus), a kingfisher endemic to Guam, was extirpated by 1988 as a result of predation by introduced brown tree snakes (Boiga irregularis) (8). Only 29 individuals were rescued, and they have subsequently been managed in Association of Zoos and Aquariums institutions across the United States, in addition to a facility on Guam (9). However, because not all of the captured birds bred successfully, the current sihek population of fewer than 140 individuals descends from only 16 genetic founders. It also suffers sex-ratio imbalances. The population therefore remains at risk, and further declines through loss of zoological institution support would hamper recovery efforts (10).

Ideally, extinct-in-the-wild populations can increase in captivity to the point that it is safe to release them back into their natural habitat. The successful reintroduction of the ko'ko' (Guam rail, Hypotaenidia owstoni) onto a small island near Guam has been heralded as a major conservation success. In 2019, the ko'ko' was reclassified from extinct in the wild to critically endangered (11). Such successes depend on full support for the zoos, aquariums, and gardens that struggle to maintain these collections. Further population declines will jeopardize recovery and increase extinction risks. We call for urgent funding to ensure that breeding, propagation, and holding facilities have the resources to care for extinct-in-the-wild species during the COVID-19 pandemic and beyond.

References and Notes

Competing Interests

A.T. is funded by the Guam Department of Agriculture and a U.S. Fish and Wildlife Service Endangered Species Section 6 grant (award numbers F16AF01007 and F18AF01285) to facilitate a conservation translocation plan for the Guam kingfisher. A.M. is a research associate for the Wildlife Conservation Research Unit at Oxford University.

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