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Given the frequency with which translocation is implemented as a conservation tool, remarkably little research has assessed the sustainable management of translocation source populations. We sought to make an a priori estimate of the impact of multiple alternative harvesting scenarios on five passerine species endemic to Norfolk Island which may benefit from future translocation. Population parameters for our five focal taxa were quantified using distance sampling at 298 point surveys conducted in 2019. Intensive nest monitoring between 2018 and 2020 was used to estimate reproductive rates. We modelled population trajectories for all five taxa under alternative harvesting scenarios in forward projections over a 25‐year period to assess the likelihood that focal populations could recover from a harvesting event. We used sensitivity analysis to assess the robustness of models to uncertainty around some population parameters. We estimate that Norfolk Island National Park supported 1486 Norfolk Robins Petroica multicolor (95% confidence interval (CI) 1017–1954), 7184 Slender‐billed White‐eyes Zosterops tenuirostris (95% CI 5817–8551), 2970 Norfolk Grey Fantails Rhipidura albiscapa pelzini (95% CI 2094–3846), 3676 Norfolk Gerygones Gerygone modesta (95% CI 2869–4482) and 1671 Norfolk Golden Whistlers Pachycephala pectoralis xanthoprocta (95% CI 1084–2259) in 2019. All five species were predicted to recover from the harvest of 50, 100 or 150 individuals within 10 years. Despite considerable variation in population parameters, we demonstrate that all five focal taxa have the potential to sustain harvesting at rates required for future conservation translocations. We provide a clear comparison of differing intensity harvesting strategies for on‐ground managers. More broadly, we provide a rare example of an a priori assessment of the impact of harvesting for translocation. [ABSTRACT FROM AUTHOR]

Trophic interactions between threatened species complicate management. Similarly, interactions between threatened species and pest species present management challenges, given that pest control can lead to non-target impacts (e.g. trophic cascades or secondary poisoning). There are records of the critically endangered Norfolk Island Morepork Ninox novaeseelandiae undulata consuming both threatened songbirds and invasive rodents that are subject to management interventions. Nevertheless, the diet of the morepork remains largely unknown. We visually screened regurgitated pellets using a microscope, alongside environmental DNA (eDNA) screening of pellets and scats, to investigate the diet of the Norfolk Island Morepork. A total of 113 pellets and 19 scats were collected between October 2020 and June 2021. All moreporks screened with eDNA metabarcoding had consumed invasive rodents and at least one-third of samples contained rodents. The owls were also found to have consumed four of five endemic songbirds and possibly an endemic parrot, most of which are threatened. Environmental DNA metabarcoding detected more taxa overall, but visual screening identified a greater richness of Orthoptera and Coleoptera in the diet. The frequency with which the Norfolk Island Morepork consumed rodents presents a conundrum for conservation managers. Control of invasive rodents is considered essential to support threatened songbirds, yet this same action places the species at risk of secondary poisoning. Urgent investigations are needed to identify effective control methods for invasive rodents that are safe for non-target species. [ABSTRACT FROM AUTHOR]

Context: Invasive rodents pose a substantial threat to biodiversity and are a leading cause of species decline and extinction on islands. Population suppression using ground-based methods is common practice, though arboreal behaviour of rodents may render control programs less effective. Aims: We aimed to quantify species-specific invasive rodent activity (Rattus rattus , R. exulans , Mus musculus) across three forest strata to determine the prevalence of arboreal rodent behaviour in a system that has undergone extensive long-term rodent baiting, and therefore assess the suitability of solely ground-based baiting in this system. Methods: We calculated rodent presence at the ground, mid-storey, and canopy using three detection methods (camera traps, chew cards and tracking tunnels) deployed for 30-day periods across three structurally distinct forest types (canopy heights ranged from 3.5 to 16.7 m). We developed continuous rodent activity indices for each method, which we paired with density estimates. Strata-specific species composition was determined using camera trap images. Key results: Rodent presence was recorded equally across all strata, with R. rattus dominating above-ground strata. Rodent densities differed significantly between forest types, which was largely consistent with activity indices. Conclusions: Our findings offer an additional explanation for reduced efficacy of long-term ground-based control programs: arboreal behaviour may exacerbate the reduction in efficacy often associated with long-term control. Implications: Effective management of invasive rodent species on islands is a global conservation challenge. Our findings suggest above-ground control may be required in some long-term suppression programs or eradication campaigns, particularly in the presence of the black rat. Introduced rodents are highly destructive island invaders the world over. Control programs are usually ground-based, however our study found that black rats (Rattus rattus) dominated the forest mid-storey and canopy, casting doubt on the effectiveness of solely ground-based programs. Including above-ground control in the conservationist's rodent control arsenal may improve outcomes for island biodiversity. [ABSTRACT FROM AUTHOR]

Island endemic birds represent approximately 90% of contemporary avian extinctions globally. Introduced predators and land-use change are key drivers of population decline in this group. Where multiple threats may compound the impacts on species, the implementation of complementary approaches to threat assessment can be especially valuable. Using Norfolk Island (NI) in the south-west Pacific as an exemplar, we assessed daily nest survival rates for five endemic songbirds (NI Robin Petroica multicolor, NI Gerygone Gerygone modesta, Slender-billed White-eye Zosterops tenuirostris, NI Whistler Pachycephala pectoralis xanthoprocta and NI Fantail Rhipidura albiscapa pelzelni), monitoring 135 nests over four breeding seasons. To understand the factors associated with suitable breeding habitat, we also conducted ecological niche modelling in Maxent for all species. Depredation was the primary driver of nest failure across all species (80% of failed nests), with invasive rats (Rattus sp.) being the most common predator (61% of depredated nests) and a key predictor of nest survival. Gerygones and Fantails exhibited the highest nest survival and were also categorised as habitat generalists using ecological niche modelling. Conversely, the three species that exhibited lower nest survival (Robin, White-eye and Whistler) had specialised habitat requirements, highlighting the potential for cumulative impacts. Our data suggest that invasive rodent control within intact forested sites is a critical management action for this system, followed by strategic habitat restoration and increased connectivity. Our study provides essential ecological information for five poorly understood island songbirds and identifies key management strategies for a regional avian hotspot. [ABSTRACT FROM AUTHOR]

A remote motion-triggered camera captured images of an adult Long-tailed Cuckoo Urodynamys taitensis visiting and possibly depredating a Norfolk Island Golden Whistler Pachycephala pectoralis xanthoprocta nest in late December 2018. This is the first documented instance of a Long-tailed Cuckoo visiting the nest of a Pachycephala species, and is a rare occurrence of this Cuckoo on Norfolk Island at this time of year. A preliminary comparison of the eggs of the Cuckoo and the Whistler indicates the Whistler as a potential brood-host for this Cuckoo on Norfolk Island. [ABSTRACT FROM AUTHOR]