Reintroduction Programs

Reintroduction programs, by which animals raised or rehabilitated in AZA-accredited zoos or aquariums are released into their natural habitats, are powerful tools used for stabilizing, reestablishing, or increasing in-situ animal populations that have suffered significant declines. Reintroductions may include animals that have spent some of their early life-stages being cared for in a “headstart” program that gives them a greater chance of survival than those born in the wild, those brought in for rehabilitation from illness or injury, those moved from one area for release elsewhere, or those that are offspring of animals that have had several generations cared for by AZA-accredited institutions.

Asian wild horse: Equus ferus przewalskii, also known as takhi and Przewalski’s horse, roamed the grassland steppes of Europe and Asia for millennia. But by the late 1960’s, it was driven to extinction in the wild due to human persecution, grazing competition, and high mortality from harsh winters. Over the next several decades, zoos worldwide bred rescued individuals and worked with in-country partners to reintroduce the descendants back to the wild. Today, there are more than 500 Asian wild horses running free in Mongolia and China. In 2014, the Asian Wild Horse SSP launched the True Wild Horse Initiative to support in situ research and conservation efforts for Asian wild horses. 

Black-footed Ferrets: In 1987, 18 of the remaining black-footed ferrets were placed into the care of AZA-accredited institutions as well as partner organizations and agencies. Due to the efforts of the AZA Black-footed Ferret SSP Program and their partners, these animals have successfully reproduced and thousands have been reintroduced into their historic range since 1991. Learn more about this species’ road to recovery.

California Condors: In 1982, only 22 California condors existed in the wild. Conservation breeding and management of these animals in AZA-accredited institutions, overseen by the California Condor SSP, increased this population to almost 200 birds within 20 years. By 2014, their population totaled 425 animals, including 219 living in the wild. To learn more about the condor's ex-situ rearing efforts visit the San Diego Zoo website. Visit the USFWS Endangered Species Program to view a video of this success story.

Ohio River Basin Freshwater Mussels: Freshwater mussels are an imperiled group of North American animals with an estimated 43% of the species found in the Ohio River basin. In 2001, the Columbus Zoo and Aquarium, the Wilds, Ohio State University, Ohio Department of Natural Resources Division of Wildlife, U.S. Fish and Wildlife Service, and the Columbus Recreation and Parks Department founded the Freshwater Mussel Conservation and Research Center.  This Center has developed innovative conservation methods which have yielded the exceptional propagation, culture, translocation, and reintroduction of numerous state and federally listed freshwater mussel species back into Ohio’s streams, rivers, and lakes.

Golden Lion Tamarin: In 2003, the previously Critically Endangered golden lion tamarin was downlisted by the IUCN to Endangered after nearly thirty years of conservation efforts involving the Golden Lion Tamarin Conservation Program (GLTCP) at the Smithsonian National Zoological Park and the Associação Mico-Leao-Dourado in Rio de Janeiro. New populations were established in Brazil’s União Biological Reserve through the translocation of 47 individuals in six isolated groups from their original isolated habitats. This reintroduction program has also contributed to the protection of 3,100 hectares of forests within the tamarins’ range.

Karner Blue Butterfly: While healthy populations of the federally endangered Karner blue butterfly remain in a handful of its historic range states, the species disappeared from Ohio in 1992. In 1998, the Toledo Zoological Gardens became the first institution to breed the Karner blue butterfly for reintroduction into the wild at restored sites and later offered assistance to the Detroit Zoological Park with releasing butterflies to a site in southeast Michigan. 

Oregon Spotted Frog: In 2014, the Oregon spotted frog was listed as Threatened under the Endangered Species Act, after having been lost from almost 80% of its historic range. The Vancouver Aquarium Marine Science Centre, working with the Oregon Spotted Frog Recovery Team in Canada on a headstart program, bred this species for the first time in 2010 and released tadpoles and metamorphs into native habitat. Other partners, led by the Washington Department of Fish and Wildlife, are engaged in its recovery in the United States, including the Oregon Zoo, Northwest Trek Wildlife Park, Point Defiance Zoo & Aquarium, and Woodland Park Zoo. 

Palila: The palila is an endangered Hawaiian honeycreeper species that has suffered population declines due to the destruction of the dry forests it inhabits. Efforts to expand the palila population back to its historic range at Pu'u Mali have included successful releases of birds bred at the Keauhou Bird Conservation Center as part of the Hawaii Endangered Bird Conservation Program run by San Diego Zoo Global, as well translocation of wild birds by the US Geological Survey. 

Red Wolf: Red wolf populations had declined significantly by the 1960s due to intensive predator control programs and loss of habitat. 14 wolves out of a remnant population found along the Gulf Coast of Texas and Louisiana became the founders of a successful breeding program involving AZA-accredited institutions and the AZA Red Wolf SSP. 

Wyoming Toad: The Wyoming toad was officially classified as Extinct in the Wild in 1994, when only one ex-situ population remained. This population was brought into the care of AZA-accredited institutions and, under the supervision of the Wyoming Toad SSP, it successfully managed to produce tadpoles and toadlets that continue to be reintroduced into the wild. AZA institutions and their partners continue to conduct regular releases of this species, as wild populations of the Wyoming toad are not yet self-sustaining. 

To learn about other reintroduction projects AZA-accredited zoos and aquariums are studying, developing, or conducting, explore the Conservation and Research Database. For reintroduction-related research projects, select “Research” as the project category, “Species and/or Habitat Conservation” as the keyword category, and “Reintroduction and Translocation” as the keyword. For field projects, select “Field Conservation” as the project category, “Ex Situ-Related” as the keyword category, and “Reintroduction” as the keyword.

AZA, the U.S. Fish and Wildlife Service (USFWS), and the International Union for the Conservation of Nature's Species Survival Commission (IUCN/SSC) play key roles in advancing the science of reintroduction programs in which AZA Animal Programs or its accredited institutions participate. Numerous reference materials and tools have been developed to advance the science and success of reintroductions.

AZA asserts that the scientific and ethical complexity of reintroduction necessitates guidelines for those who plan, conduct, fund, regulate and publicize reintroductions and in 1992 developed a bibliography that identified a variety of documents addressing reintroduction guidelines.  These guidelines are often contradictory and AZA has suggested that sincere consideration be given to all bibliographic sources and guidelines during the planning stages of reintroduction, and that reintroduction be regarded as science, with surveys of the pertinent literature, interdisciplinary participation, formulation of testable hypotheses and goals, thorough documentation, rapid publication of results, and review of the program by independent referees be incorporated.  Read more about the AZA Guidelines for Reintroduction of Animals.

The Reintroduction Specialist Group (RSG) promotes the reintroduction of viable populations of animals and plants back to their natural ecosystems, contributing to conservation efforts worldwide. The RSG manages a network of global voluntary members to provide reintroduction practitioners with tools such as reintroduction guidelines, networking resources, and publications to provide a means for distributing information on reintroduction projects. Practitioners are encouraged to explore the RSG’s website for the most current resources about reintroduction and other conservation translocation efforts.

In 2008, Lincoln Park Zoological Gardens established an Avian Reintroduction and Translocation Database (ARTD) to centralize information about the avian species, release sites, and release events that take place around the world. The database describes every aspect of the reintroduction effort for each species including the variables that impact the efficacy of releases, species biology and ecology, habitat suitability, demography, and genetics.