Adaptive Management of the Regent honeyeater: Song Culture and Conservation

Abstract

Captive breeding for release is an increasingly important tool in the conservation of species. Despite ever more rigorous management, the success of translocations, population supplementations and re-introductions remains variable. A suite of factors may negatively impact the success of these programs, amongst these are a divergence between captive and wild animal cultures. Animal cultures are behaviours which are acquired from conspecifics through some form of social learning and maintained at a population or community level. In recent years the importance of animal cultures has been increasingly recognised in conservation.

A key example of animal culture is provided in the context of birdsong where some 40% of bird species learn their songs. Birdsong has important functions in territory establishment, pair formation and group cohesion, and as such impacts individual fitness. A divergence between captive and wild song cultures, therefore, may hinder the efforts of reintroductions. In such cases, adaptive management of captive breeding programs is necessary to identify and reduce the divide between captive and wild song cultures. The critically endangered regent honeyeater (Anthochaera phrygia) provides a clear example where captive breeding and release is critical to the recovery of the species, but song culture differs between captive and wild populations. This thesis explores the song culture of the regent honeyeater, both in the wild and captivity. It assesses the fitness implications to individuals and the risks to the success of the reintroduction program and provides a rare demonstration of cultural restoration within an applied conservation breeding setting.

In chapter 2 I review the literature surrounding animal cultures, the implications for the preservation and restoration of animal cultures. In chapter 3 I (with my colleagues) tested the song preferences of female zoo-bred. Females were presented with bouts of familiar zoo-bred songs, unfamiliar wild-type songs, and the songs of another species. We found that female zoo-bred birds showed a significant preference for the songs of zoo-bred males over the songs of wild males, across all measures tested. We show for the first time the risk of assortative mating based upon divergent wild and captive song cultures. In chapter 4 we attempted to reduce the divide between wild and captive regent honeyeaters by implementing a song tutoring program. Over three breeding seasons within the applied breeding system, we undertook adaptive song tutoring experiments using combinations of song broadcast and live tutoring from two wild-origin males to teach zoo-bred juveniles the wild song. Using just two wild founders, we show how animal cultures can be restored in ex-situ populations with simple modifications to husbandry protocols. In Chapter 5 we monitor ongoing changes in wild regent honeyeater song culture and report a dramatic shift in the dominant song type. Between 2015 and 2019, most males in the Blue Mountains sang a typical regent honeyeater song ('Typical Blue Mountains song'), but 5-10% sang an abbreviated version of the song with half the number of syllables (the 'Clipped Blue Mountains song'), which was associated with lower pairing success. Since 2020, the proportion of males singing the Clipped Blue Mountains song has increased to 50-75%. The likelihood of successful pairing in these males showed a significant concomitant increase, suggesting that the fitness costs associated with singing the abbreviated song decreased as it became the dominant song type. In chapter 6 we draw upon 3 years of study of Regent honeyeater song culture research to provide insights into the species' song learning process. This chapter provides guidelines for animal managers in the breeding program for critical learning periods and provides evidence of the long-term retention of songs in individuals Show more