Animal Conservation最新文献

Translocation outcomes in connected habitats are often uncertain, as individuals dispersing outside managed areas are exposed to threats. Post-release monitoring can reduce uncertainty by revealing how dispersal and habitat selection influences establishment and population growth which inform future translocations. We undertook post-release monitoring to identify habitat selection patterns following a translocation of toutouwai (North Island robin, Petroica longipes) to a large, contiguous forest habitat. Post-release monitoring aimed to estimate survival, dispersal, and territory establishment to inform management decisions and future release site selection. We created species distribution models using monitoring data to identify differences in habitat selection during the post-release dispersal and territory establishment phases. Toutouwai dispersed across 1312 ha but established territories within only 113 ha and 1 km from the release location. Site fidelity was higher than predicted, and there was no difference in dispersal or habitat selection across demographic groups. Critically, high site fidelity suggested that the extent of managed habitat was sufficient to protect dispersing individuals. Habitat selection preferences were stronger during territory establishment and were associated with lower slopes, higher water deficit and proximity to water reservoirs. Species distribution modelling allowed for predictions of high-quality core habitat where dispersal and territory establishment were more likely, resulting in targeted management to improve population growth. Our results show that initial dispersal in connected habitats may be much larger than suggested by territory data alone, and that management may need to protect larger areas to support successful establishment. We demonstrate how effective post-release monitoring can inform predictions of habitat quality and dispersal and guide management actions to improve translocations outcomes.

Control of introduced predators is essential for conserving many threatened species, but species range in vulnerability. Therefore, efficient conservation management requires estimating the vulnerabilities of different threatened species to introduced predators. Here, we quantify population responses of reintroduced toutouwai (Petroica longipes), popokatea (Mohoua albicilla) and tīeke (Philesturnus rufusater) to incursions of stoats (Mustela erminea) and cats (Felis catus) to a 588-ha predator-fenced sanctuary in Aotearoa New Zealand. There were fewer than 0.5 detections per year for both predator species from 2004 to 2016, but stoat detections increased >10-fold from 2017 to 2019 and cats >30-fold from 2020 to 2021. We estimated the growth and persistence of each bird population pre- and post-2017. This involved fitting integrated population models to survival, reproduction and count data for toutouwai and tīeke, and fitting a variation of the Moran–Ricker model to 5-min point counts for popokatea. We used these models to derive λ_max, the finite rate of increase at zero density, which must be >1 for a population to persist. Popokatea showed no sign of impacts, with λ_max estimated to be 1.68 (95% CRI 1.49–1.97) up to 2017 and 1.87 (1.42–2.62) after 2017. Toutouwai had tentative decreases in survival and reproduction, dropping the estimated λ_max from 1.28 (1.10–1.51) to 1.06 (0.83–1.41). Tīeke survival dropped dramatically from 2017 to 2019, but returned to pre-2017 levels when stoats were reduced, but recruitment was reduced and remained low, presumably due to cats. λ_max was estimated to be 1.74 (1.04–2.70) on pre-2017 rates; 1.14 (0.80–1.71) if only recruitment were predator-affected; and 0.79 (0.36–1.36) if both adult survival and recruitment were predator-affected. Our results therefore indicated that this level of stoat and cat incursion was inconsequential for popokatea, tentatively reduced toutouwai persistence from safe to marginal, and would have driven tīeke to extinction.

Conservation translocation is a valuable management tool for conserving and restoring biodiversity. Conservation managers and researchers strive for translocation success and spend considerable time and energy planning for a positive outcome. However, many translocations fail. Defining what makes a translocation ‘successful’ can be challenging. Criteria for success must be relevant to the objectives of the translocation, should be measurable and have realistic timeframes for achievement. How we evaluate these criteria is highly dependent on our ability to monitor a species effectively, which may be complicated by its behaviour, the release methods used, or the release environment, including sympatric species. Well-planned, but ultimately ineffective, monitoring strategies may render some criteria difficult or impossible to evaluate. Finally, poorly defined success criteria may result in apparently successful translocations failing to achieve their stated goals, or translocations that meet their success criteria but ultimately fail. Here, we discuss the challenges faced when defining and evaluating the success of a fauna reconstruction program on Dirk Hartog Island in Western Australia. Our achievement of success criteria within prescribed timeframes has been mixed, highlighting ways to better define and measure success. We discuss how we have adapted to new knowledge as the translocations progressed and propose frameworks for defining performance measures and guiding decision-making in response to failures in achieving success criteria.

Recovery of endangered species is challenging and lengthy, especially when it involves reintroduction and dynamic environmental conditions. Because managers often need to decide between many management strategies with uncertain outcomes, periodically assessing progress toward recovery using population viability analysis (PVA) can help guide decision-making. We developed a PVA for the critically endangered Puerto Rican parrot (Amazona vittata) to evaluate current status and potential future management strategies to reach goals set in the Recovery Plan. Having grown from their nadir of 13 birds in 1976 to 686 in 2021, the recovery effort has made great progress. Using 15 years of data, we built an individual-based PVA that included interactions between two captive and three wild populations connected via annual releases. If management continues as planned, the wild populations have no to moderate risks of extinction (0–32%) over the next 100 years. However, wild populations remain dependent on releases to sustain growth, and recovery targets for stable population growth and connectivity have not yet been reached. Our analysis suggests that hurricanes are an impediment to reaching recovery targets and impact some wild populations more than others based on geography. Projections with climate-change-induced higher hurricane impact resulted in wild populations being less likely to stabilize. We identified demographic rates and associated management strategies that could positively impact wild populations: increasing reproduction (e.g., via increasing artificial nests, improving nest success) and decreasing first-year mortality (e.g., via targeted predator control). Based on our current understanding of Puerto Rican parrot demographics, species recovery will continue to be management-dependent unless demographic rates can be altered. As more data are gathered, especially for data-sparse populations and in the face of environmental change, future iterations of this model can re-evaluate progress, update management strategies, and provide support for deciding if and when to delist this iconic species.