Captive breeding to bolster wild populations of endangered species changes the bodies, behavior and health of captive-bred animals, thereby decreasing their chances of survival after they’re released into the wild
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A handful of orange-bellied parrot (Neophema chrysogaster) chicks, comprising a huge proportion of … [+]
Increasingly perceived as a panacea for doomed species, captive-breeding-for-release programs, which are often last-ditch conservation efforts reserved for the most critically endangered species, may instead be harming the very species they are intended to help. A recently published review of the scientific literature on captive breeding for conservation purposes has documented some disturbing findings: animals bred in captivity as part of captive-breeding-for-release efforts are showing significant phenotypic changes — physical and behavioral changes — that may reduce their survival chances once released into the wild, according to a team of conservation biologists based at The Australian National University (ANU).
According to the study’s authors, the conditions that animals experience in captivity are often very different to what they face in the wild, which can cause them to change in a number of ways. Some of these changes are obvious but others are more difficult to indentify. Nonetheless, these changes can limit the effectiveness of reintroduction programs for threatened species.
F I G U R E 1 : (A) Monarch butterflies (Danaus plexippus) are migratory, but captive-bred … [+]
These phenotypic changes include butterflies that forget how to migrate after release to the wild, captive-bred big cats with weaker jaws because they are maintained on a diet of ground meat, songbirds that learn the wrong song in captivity thereby preventing them from breeding in the wild, captive-bred quolls that have lost their fear of predators only 13 generations (years) after translocation to predator-free islands, and captive-bred parrots whose wing shapes differ significantly from their wild relatives, making them less capable of surviving long-distance migratory flights.
Captive-bred regent honeyeaters (Anthochaera phrygia) are losing their natural songs, which prevents … [+]
“The world is facing an extinction crisis, and many people are doing the best they can to save at-risk species. Captive breeding and release will become an increasingly important tool to save species from extinction,” said study co-author, conservation biologist Dejan Stojanovic, a postdoctoral fellow at ANU who researches the conservation and management of threatened species and their habitats, with a special focus on how species cope with habitat loss.
“But our review shows that breeding animals in captivity may sometimes result in unexpected changes that could disadvantage them after their release to the wild”, Dr Stojanovic continued. “If animals change in captivity to the point that they have difficulty surviving and breeding in the wild, then we need to take a closer look at why this problem arises and work out how to fix it.”
In this review, the study’s authors highlight several major knowledge gaps that they distilled into the following questions that they hope will galvanize future funding and research efforts:
- To what extent, and how rapidly can captive-bred animals re-acquire wild phenotypes after they’ve been released?
- What is the relationship between captive phenotypes, fitness outcomes and demographic responses of wild populations after release?
- How does the ratio of captive-bred to wild conspecifics affect the maintenance or re-establishment of wild animal behaviors and culture?
- How important is age at release in determining the phenotypic costs of captivity?
- How pervasive are links between phenotypic traits and how do these traits interact with each other?
Answering these questions will require a much closer documentation of the phenotypes of captive animals, and better integration of the outcomes of captive breeding with the fate of wild populations (Figure 2).
F I G U R E 2 : Conceptual pathway for reducing the impact of captive phenotypes on the success of … [+]
“Importantly, we hope our review demonstrates there are a range of opportunities to study why these changes occur, what impacts they have and how we can address them to help give captive-bred animals the best possible chance of flourishing in the wild.”
Source:
Ross Crates, Dejan Stojanovic and Robert Heinsohn (2022). The phenotypic costs of captivity, Biological Reviews | doi:10.1111/brv.12913
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