REPORT TO THE U.S. FISH AND WILDLIFE SERVICE FOR HAWAIIAN STILT ENDANGERED SPECIES PERMIT: TE-25955C-1 REPORTING PERIOD JANUARY 01, 2019 – DECEMBER 31, 2019 SUBMITTED BY: Melissa R. Price Assistant Professor University of Hawaii-Manoa 1910 East-West Road Sherman Hall Rm 118 Honolulu, HI 96822 Phone: 808-956-7774 Email:
[email protected] January 31, 2020 1 2 EXECUTIVE SUMMARY 3 The Hawaiian Stilt (Himantopus mexicanus knudseni) is an endangered subspecies of the 4 Black-necked stilt (Himantopus mexicanus) that inhabits wetlands throughout the Hawaiian 5 Islands. Depredation of eggs and chicks by introduced predators is a major threat to Hawaiian 6 Stilt populations. Where and when a bird decides to nest may impact the likelihood of egg or 7 chick depredation. Nesting in close proximity to water may decrease depredation rates by 8 mammals, as water can act as a barrier to mammalian predators, does not hold scent, and 9 provides an obstacle-free escape route for chicks. Alternatively, some mammalian predators may 10 be attracted to water, and a number of aquatic species have been identified as predators of 11 Hawaiian Stilt chicks, including the American Bullfrog (Lithobates catesbeianus). Vegetation 12 height is also an important factor for egg and chick survival, as taller vegetation may help 13 conceal nests and chicks from predators, particularly aerial species. Additionally, depredation is 14 often not constant across the breeding season due to changes in parental activity, nest and chick 15 abundance, or habitat characteristics. The Hawaiian Stilt nests from February to September 16 across the Hawaiian Islands.