Born to Be Wild: Evaluating the Zoo-Based Regent Honeyeater Breed for Release Program to Optimise Individual Success and Conservation Outcomes in the Wild

Abstract

Evaluating the effectiveness of captive breeding programs is central to improving conservation outcomes in released animals. However, few studies have assessed the impact of the strategies and trade-offs involved in husbandry decisions and the selection of traits on the success of breeding programs. This study evaluated a range of husbandry features including an animal's environment, health, and traits of the released individual and its parents involved in the zoo-based Regent Honeyeater breed for release program to optimise individual reproductive success and survivability, leading to improved conservation outcomes in the wild. We analysed 285 birds using a penalised Cox proportional hazard model to assess survival and an ordinal logistic model to evaluate the reproductive success of zoo bred birds released to the wild. Key features identified by the study highlight the importance of having parents that are successful breeders and parents that have an overall higher lifetime reproductive output. However, there were associated quantity-quality trade-offs, as the success of young (i.e., released birds) produced by parents was negatively associated to the number of clutches per year (where one clutch per year was found optimal). The study demonstrated the importance of considering the parental effects on the traits of its offspring beyond its pedigree information and found there was an associated decline in fitness of its offspring with older fathers. Song tutoring using wild Regent Honeyeaters was also important for increased survival post-release. Other important factors are discussed within the review. In general, the study recommended that a multi-faceted approach in the assessment and evaluation of the captive breeding program, to identify markers that will improve conservation outcomes of future releases.

The phenotypic costs of captivity

“…Analytical approaches are available to contrast the potential outcomes of releasing different age classes (Robert et al ., 2004) and such approaches should be implemented alongside experimental releases that can inform underlying model assumptions. Other reasons that individuals may be unsuitable for release include biosecurity risks, inappropriate behaviours for life in the wild, or because some other phenotypic trait makes them less likely to thrive after release (Tripovich et al ., 2021). There is unlikely to be a ‘one size fits all’ rule for which individuals are most likely to achieve reintroduction aims.…”

“…Conservation practitioners should be prepared to attempt multiple, small‐scale ‘experimental’ releases to test a‐priori hypotheses with rigorous post‐release monitoring and refine bespoke strategies though adaptive management. Such attempts can reveal useful insights about how to improve reintroduction success (Tripovich et al ., 2021; Troy & Lawrence, 2021).…”

The endangered brain: actively preserving ex-situ animal behaviour and cognition will benefit in-situ conservation

“…In zoos, there has been an overwhelming focus on environmental enrichment that recreates naturalistic-looking environments but is also motivated by giving aesthetic and educational value to visitors [10,[158][159][160]. From the published literature, it seems conservationfocused enrichment has a number of goals including increasing behavioural diversity and skill learning [143,[147][148][149]161]. A recent meta-analysis of 41 vertebrate translocations found that enrichment is associated with higher survival [162], but the authors did not identify which element(s) of enrichment are linked to survival success.…”

Altered wing phenotypes of captive‐bred migratory birds lower post‐release fitness

“…Wing shape strongly predicts flight efficiency (Lockwood et al, 1998; Sheard et al, 2020). Given that migratory birds are commonly bred in captivity for reintroduction (Burnside et al, 2017; Davis, 2010; Hutchins et al, 2018; Stojanovic, Potts, Troy, et al, 2020; Tripovich et al, 2021), quantifying the ubiquity of deleterious captive wing shape phenotypes and their post‐release fitness consequences is critical information.…”