Assessing the potential of translocating vulnerable forest birds by searching for novel and enduring climatic ranges

Abstract

Hawaiian forest birds are imperiled, with fewer than half the original >40 species remaining extant. Recent studies document ongoing rapid population decline and project complete climate‐based range losses for the critically endangered Kaua'i endemics ‘akeke’e (Loxops caeruleirostris) and ‘akikiki (Oreomystis bairdi) by end‐of‐century due to projected warming. Climate change facilitates the upward expansion of avian malaria into native high elevation forests where disease was historically absent. While intensified conservation efforts attempt to safeguard these species and their habitats, the magnitude of potential loss and the urgency of this situation require all conservation options to be seriously considered. One option for Kaua’i endemics is translocation to islands with higher elevation habitats. We explored the feasibility of interisland translocation by projecting baseline and future climate‐based ranges of ‘akeke’e and ‘akikiki across the Hawaiian archipelago. For islands where compatible climates for these species were projected to endure through end‐of‐century, an additional climatic niche overlap analysis compares the spatial overlap between Kaua’i endemics and current native species on prospective destination islands. Suitable climate‐based ranges exist on Maui and Hawai'i for these Kaua'i endemics that offer climatically distinct areas compared to niche distributions of destination island endemics. While we recognize that any decision to translocate birds will include assessing numerous additional social, political, and biological factors, our focus on locations of enduring and ecologically compatible climate‐based ranges represents the first step to evaluate this potential conservation option. Our approach considering baseline and future distributions of species with climatic niche overlap metrics to identify undesirable range overlap provides a method that can be utilized for other climate‐vulnerable species with disjointed compatible environments beyond their native range.

Minimizing extinction risk in the face of uncertainty: Developing conservation strategies for 2 rapidly declining forest bird species on Kaua‘i Island

“…For example, translocation of ‘akikiki and ‘akeke‘e to forests on other islands where disease is absent was considered a viable approach to remove individuals from immediate threat but still keep them in the wild. The option of translocating ‘akeke‘e to Maui was especially appealing, as environmental conditions are comparable (Fortini et al 2017) and the Maui ‘akepa ( Loxops ochraceus ), a sister species to ‘akeke‘e (the Kaua‘i ‘akepa) is extinct (Reynolds and Snetsinger 2001). Thus, the conservation introduction of ‘akeke‘e on Maui would potentially prevent extinction of ‘akeke‘e on Kaua‘i while also providing a surrogate species to help restore historical ecological function in Maui forests.…”

Perceived Barriers to the Use of Assisted Colonization for Climate Sensitive Species in the Hawaiian Islands

“…The possibility of any additional pressure on endemic and endangered Maui and Hawaiʻi species was expressed by managers, as population sizes of many native species are likely declining (Fortini et al 2013;Fortini et al 2015). However, evaluation of potential translocations of critically endangered single-island endemics from Kauaʻi to Maui or Hawaiʻi island indicates that there is minimal potential for competition and range overlap among candidates for translocation and resident native species (Mountainspring and Scott 1985;Scott et al 1986, Fortini et al 2017.…”

Improved status of the conservation reliant Oahu Elepaio through effective management and natural adaptation

“…VanderWerf et al (2006) found that pox prevalence was higher in years with higher rainfall, which presumably created more breeding habitat for mosquitoes. Climate change is expected to allow altitudinal range expansion of mosquitoes in Hawaii, which would increase the severity of this threat for other Hawaiian forest birds (Atkinson & LaPointe, 2009; Benning et al, 2002; Garamszegi, 2011; Paxton et al, 2016, Fortini et al, 2017), but not for the Oahu Elepaio because the island has no mountains high enough to provide refuge from the cold‐intolerant mosquitoes that carry the pathogens, and mosquitoes are already present throughout their range (VanderWerf et al, 2006).…”