Contributions of zoos and aquariums to reintroductions: historical reintroduction efforts in the context of changing conservation perspectives

The world faces a biodiversity crisis and efforts are needed to protect species from extinction. Reintroductions using source populations from zoos and aquariums offer a technique to re-establish species in the wild following extinction or population depletion beyond sustainable limits. Ex situ populations are a potential source for reintroduction projects but many zoos and aquariums do not necessarily maintain globally rare species. We aimed to quantify the contribution zoos and aquariums make to reintroductions, and evaluate how European Association of Zoos and Aquaria (EAZA) members have contributed to reintroduction projects. Data on the contribution zoos and aquariums make to reintroductions were extracted from the Global Re-introduction Perspectives publications, and the EAZA membership was surveyed on historical reintroduction projects. This information was augmented with data from The IUCN Red List of Threatened Species and Species360 Zoological Information Management System (ZIMS). The majority of species in EAZA-member institutions were not globally threatened but more than half of the 156 reintroduced species and 260 projects supported by EAZA members concerned species that were threatened (i.e. Critically Endangered, Endangered or Vulnerable), Near Threatened or Extinct in the Wild. Most species that were not of global conservation concern were locally rare. EAZA members provided animals for release, but their greatest contributions to reintroduction projects were funds, staff, expertise and equipment, and project coordination. Zoos and aquariums have an important role to play in reintroductions especially as emphasis shifts away from the in situ–ex situ dichotomy and towards integrated conservation management of species.