Understanding Post-Release Dispersal and Habitat Selection Helps Refine Management of Translocated Populations

Abstract

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.