Captive breeding as a tool for species conservation

Abstract

Conservation breeding programs and other forms of ex-situ management exist worldwide for a huge variety of taxa. These programs often have dual goals of preserving an insurance population in captivity and breeding individuals for release to supplement declining wild populations. Despite the popularity of ex-situ management, conservation breeding programs are costly, time-consuming, and have no guarantees of success. Species may fail to breed in captivity, develop deleterious adaptations to a captive environment, or survival post-release may be too low to contribute to wild population recovery. The goal of this thesis is to explore how conservation breeding programs are represented in the literature, understand what can be learnt from long-running programs, and utilise this knowledge to inform future recovery efforts. My primary study species is the orange-bellied parrot (Neophema chrysogaster), a critically endangered bird that has been bred in captivity since the mid-1980's. This thesis starts populating some of the gaps in the literature with the goal of asking important, real-world questions that could have direct implications on management and inform evidence-based decision-making both for this species and others. The first chapter of this thesis explains the background and study species in detail, framing how the subsequent research chapters contribute to these broader themes. Chapter 2 provides a scoping review of the literature, with a focus on understanding how conservation breeding and reintroduction programs are represented in the literature and highlighting research gaps. For any conservation breeding program to succeed, animals need to reproduce in captivity. Chapter 3 therefore attempts to understand what common factors could be influencing orange-bellied parrot reproductive success in a captive environment. To understand whether an early life in captivity might disadvantage a bird in future, in Chapter 4 I looked at physical growth of nestlings to determine what components of a individuals' early life might have carry-over effects on either physical growth or survival. This research demonstrates previously undetected carry-over effects of early life on survival, and potentially gives managers another tool to help improve first-year survival of both wild and captive-bred juveniles. Chapter 5 focuses on birds after they are released and how they integrate socially into the wild population. Social structure and integration are important both to have the safety of a large flock and for birds to learn important skills necessary for survival. I constructed social networks of wild orange-bellied parrots to determine whether captive-bred individuals differed socially from their wild conspecifics, and whether an individuals' social position impacts its probability of survival. Chapter 6 takes the themes and research explored in previous chapters and applies them to the future. I utilised data from existing conservation breeding programs to build a series of population models to gain a realistic understanding of how releasing individuals from captivity could impact the wild population of critically endangered swift parrots (Lathamus discolor). The final conclusion weaves together knowledge and insight from all the chapters with a focus on informing evidence-based decision-making processes regarding ex-situ conservation efforts. Show more