Abundance and demography of the Hawaiian hawk: Is delisting warranted?

摘要: To provide the U.S. Fish and Wildlife Service (USFWS) with updated information on Hawaiian hawk ('io, Buteo solitarius) for reconsideration of its current endangered status, we determined population size, distribution, habitat availability, survival, fecundity, finite rate increase (λ) 'io during 1998 1999 island Hawaii. We estimated total at 1,457 ± 176.3 SE 'io. Birds were broadly distributed around island, but highest densities found in mature native forest a grass understory (0.57 0.12 'io/km 2 ). that 58.7% (6,144 km ) was usable Of habitat, 31.8% (1,954 currently is protected by state federal forests, parks, refuges. Based an average density 0.24 0.08 those areas, calculated areas support 469 (95% CI: 244-901). In all habitats combined, first-year adult survival 0.50 0.10 0.94 0.04, respectively, fecundity 0.23 0.04 female young/breeding female. Overall, λ 1.03 0.04. Elasticity analyses showed to be most important parameter regulating growth this population. The appears viable based approximately 1 high survival. Additionally, substantial are protected, appear resistant avian diseases no evidence exists negative impacts from contaminants, birds show ability use human-altered landscapes exotic prey. Because short study duration, relatively low variance our estimates (abundance, λ), environmental stochasticity, believe delisting nonthreatened status unwarranted. However, downlisting threatened would appropriate species, or embracing listing as near under International Union Conservation Nature (IUCN) Red List categories. Regardless change political size especially survivorship should routinely monitored.