92 J. S. Tripovich et al.


However, each breeding nest that fails limits recruitment into the population. Predation from avian and mammalian predators on


eggs, nestlings and attending females is a major cause of nest failure (Taylor et al., 2018). There are also threats from competitor bird species such as the noisy miner, which aggressively competes with regent honeyeaters through disturbance or nest destruction. This species poses a threat to some of the monitored nesting regent honeyeaters and has been listed as a key threatening process under the Envi- ronment Protection and Biodiversity Conservation Act (Commonwealth of Australia, 2014; Crates et al., 2023). Ex- treme weather events such as bushfires and heavy rain have also led to habitat and nest destruction, affecting fledgling recruitment and nest integrity, and are postulated to be the cause of c. 11% of nest failures (R. Crates, pers. comm., 2022). Regent honeyeaters are most vulnerable during the nest phase because of their immobility, especially during the early stage of development. Once fledged, they have a greater chance of survival and of contributing to the greater population, reinforcing the importance of interventions at the nest stage for the recovery of the species.


Conservation challenge


Providing nest protection to regent honeyeaters is challen- ging as the birds rarely breed in the same location in consecutive years. This challenge is exacerbated by the critically low population. Regent honeyeaters are largely nomadic and can travel hundreds of kilometres (Crates et al., 2022). They often construct open-cup nests in the outer canopy that are inaccessible to humans (and thus difficult to manage for conservation) but vulnerable to com- petition or predation by various birds and mammals. They mostly breed from late August but can start to


breed in late July/early August, so for practitioners to be able to offer nest protection the birds and nests would need to be detected from the commencement of the breed- ing season to c. early September, to maximize the number of viable nests available. Additional challenges include the initial detectability of the birds, the inaccessibility of nests high in trees and that the birds will only tolerate limited disturbance. Additionally,many nests are located on private land, with associated access challenges for practitioners seeking to protect nests. There are also other challenges, such as engaging with ethics committees and government agencies for permits and licences. In 2016, an expert elicitation was undertaken to help


guide nest protection measures for regent honeyeaters. The research considered three potential actions: (1) the fit- ting of tree collars to minimize access to nests for mamma- lian predators; (2) the addition of nest cages to offer further protection to nests in collared trees; and (3) supplementary feeding to improve the ability of breeding adults to


successfully rear offspring (Canessa et al., 2020). The recov- ery team dismissed the removal of predators because most were native (and some threatened, such as the squirrel glider Petaurus norfolcensis). As a result of the analysis, tree collaring was deemed a suitable nest protection method. The approach taken by the species managers at the time was intentionally risk averse because of the limited knowl- edge of any unintended impacts of interventions. However, since then the species has continued to decline, and popu- lation modelling has emphasized the need to increase wild recruitment (Heinsohn et al., 2022). Here, as part of an adaptive management process, we build on that knowledge and explore further options such as the removal of preda- tors and other innovative measures to protect nesting regent honeyeaters. Our aim is to develop a collaborative approach amongst conservation practitioners, researchers and key stakeholders to share knowledge and ideas and discuss strategies for protecting regent honeyeater nests. We evaluate the prob- ability of success of the interventions based on expert assessments.


Methods


We adopted a four-stage approach to the development of the nest protection decision strategy tool: brainstorming ses- sion, pre-expert elicitation, expert elicitation and future planning. This process initially considered three categories of threats (avian predators, mammalian predators and ex- treme weather events), with a fourth category, avian com- petitors, added during the expert elicitation process.


Brainstorming session


The purpose of the brainstorming workshopwas to generate blue-sky thinking on avian predation, mammalian preda- tion and extreme weather events, in which all ideas for nest protection interventions were encouraged; this in- cluded additional ideas/interventions that did not fall within the scope of these three categories (Table 1). We held the brainstorming session on 26 April 2022, with 27 participants from government, not-for-profit, academia/ research and industry (Supplementary Table 1a). At this workshop we heard from a range of speakers who had worked on regent honeyeaters, including G. Taylor, who presented the results from the expert elicitation that was undertaken on regent honeyeaters in 2016 (Canessa et al., 2020), and conservation practitioners who have worked on closely related species and conservation issues. Topics dis- cussed included innovation in conservation science, and several case studies that included olfactory misinforma- tion training for mammalian predators, taste aversion train- ing to protect nesting hooded plovers Thinornis rubricollis,


Oryx, 2025, 59(1), 91–100 © The Author(s), 2024. Published by Cambridge University Press on behalf of Fauna & Flora International doi:10.1017/S0030605324000942


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