Video monitoring reveals novel threat to Critically Endangered captive-bred and released Regent Honeyeaters

Abstract

Nest predation is a primary cause of nest failure in open cup nesting woodland birds and low reproductive success is a common reason that reintroduced species fail to establish in the wild. We used video monitoring to record the breeding outcomes and identify the causes of nest failure in a reintroduced population of the Critically Endangered Regent Honeyeater. We intensively monitored 28 nesting attempts of 13 pairs during the 2015 breeding season, and found that the probability of individual nest success was 0.21 (from egg laying to fledging). We report for the first time Sugar and Squirrel Gliders depredating Regent Honeyeater nests. In addition to losses attributed to predation, a high proportion of chicks died in the nest from unknown causes. Our results show that rates of nest initiation and success are low in reintroduced Regent Honeyeaters, and future reintroductions 2 should attempt to mitigate the threat of nest predation. Other sources of nest failure and barriers to nest initiation and egg laying are priority areas for future research.

Contemporary breeding biology of critically endangered Regent Honeyeaters: implications for conservation

“…Recent work by Taylor et al . () shows that captive‐bred Regent Honeyeaters have a 48% lower rate of nest success than our estimate for wild conspecifics. Given substantial funds invested in the breeding and release of captive birds (Canessa et al .…”

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

“…Offspring born to parents that had two clutches in a season had lower predicted survival (i.e., 67.3%), and survival decreases with increasing number of clutches. In a natural setting, Regent Honeyeaters will typically produce a single clutch and may produce a second clutch if conditions are favourable (SWIFFT, 2020) or if the initial nest failed (Taylor et al, 2018). As offspring fitness is related to resource investment, the study suggests that there is a decline in the resource allocation in progeny from the second, third and fourth clutch, even in a captive setting.…”

“…Reproductive output is low across both wild and captivebred birds (Taylor et al, 2018) and it is therefore difficult to analyse reproductive success with sufficient power. Therefore, we have used ordinal categories of reproductive stages to examine reproductive success of the captive bred birds.…”

Risk aversion and uncertainty create a conundrum for planning recovery of a critically endangered species

“…Postrelease survival, at least in the short term, has been high (Taylor et al, unpublished data), but breeding success has been poor, with high levels of nest predation by avian and mammalian species including threatened native predators such as squirrel gliders (Petaurus norfolcensis) (Taylor et al, 2018). Postrelease survival, at least in the short term, has been high (Taylor et al, unpublished data), but breeding success has been poor, with high levels of nest predation by avian and mammalian species including threatened native predators such as squirrel gliders (Petaurus norfolcensis) (Taylor et al, 2018).…”

“…The regent honeyeater recovery team sought to maximize the viability of the reinforced population at Chiltern Mt-Pilot National Park. Postrelease survival, at least in the short term, has been high (Taylor et al, unpublished data), but breeding success has been poor, with high levels of nest predation by avian and mammalian species including threatened native predators such as squirrel gliders (Petaurus norfolcensis) (Taylor et al, 2018). Causes of poor nest success mirror result in the remnant wild population in New South Wales (Crates et al, 2018).…”