PS 22-53 - CANCELLED - Where kāhuli wander: Quantifying post-release dispersal of an endangered Hawaiian mollusk to inform translocation strategies

Abstract: Hundreds of species in the Hawaiian Islands have no overlap between current and future climate-suitable habitat. Species unable to naturally migrate to these discrete areas will need assistance. However, assisted translocations can result in high mortality in relocated animals establishing novel home ranges to meet their ecological needs. Instances where individuals represent a large proportion of the population, as is the case with endangered species, amplify the importance of optimizing strategies to reduce translocation mortality. Hawaiian tree snails, known as kāhuli in the Hawaiian language, have dramatically declined over the last century due to invasive predators, habitat loss, and climate change. Invasive predators such as rats, predatory snails, and Jackson’s chameleons have caused dramatic declines and even extirpation in wild populations, but predator-exclusion fences are effective at protecting snails from all three predators. Efforts are currently underway to translocate captive-bred and remaining wild snails into predator-exclusion fences in climate-suitable areas outside their known historical range. These translocations provide an optimal case study in which to examine home range establishment of a climate-sensitive species following release. In this study we used capture-mark-recapture techniques to evaluate movement patterns and home range establishment of translocated Achatinella concavospira, a species endemic to the Wai‘anae mountains on the island of O‘ahu. Via unique color patterns and shell features, we used photo identification software to photo-mark snails for a capture-mark-recapture study. Snails established stable home ranges within 1-2 months of release, approximately 5 - 15 meters from the release location. Following this time period, large movements ( >5 horizontal m) of individual snails were rare. As climate-induced habitat-shifts maroon increasing numbers of climate-sensitive species, assisted translocations will be a necessary tool in preventing biodiversity loss. These results demonstrate that, barring early mortality due to novel threats, translocated populations are likely to establish novel home ranges and persist when translocated into climate-suitable habitat.