Distribution and Trends of Endemic Hawaiian Waterbirds

Authors

Eben H. Paxton, U.S. Geological Survey Pacific Island Ecosystems Research Center
Kevin Brinck, University of Hawaiʻi at Hilo
Adonia Henry, Scaup & Willet LLC
Afsheen Siddiqi, Hawai‘i Department of Land and Natural Resources
Rachel Rounds, U.S. Fish and Wildlife Service
Jennifer Chutz, DCI West Biological Consulting LLC

Document Type

Article

Date of this Version

3-13-2021

Citation

Waterbirds 44(4): 425-437, 2021.

Comments

U.S. government works are not subject to copyright.

Abstract

Four endemic species of wetland-dependent waterbirds occur on the main Hawaiian Islands, all of which have experienced sharp population declines and are listed as endangered species. Twice per year, state-wide surveys are conducted to count waterbirds, but these surveys are evaluated only infrequently. We used a state-space approach to evaluate long-term (1986–2016) and short-term (2006–2016) trends and current distribution and abundance of endemic Hawaiian waterbirds. The most numerous species was the Ae‘o, or Hawaiian Stilt (Himantopus mexicanus knudseni), with a 5-year estimated average abundance of 1,932 individuals, followed by ‘Alae Ke‘oke‘o, or Hawaiian Coot (Fulica alai), with 1,815 individuals, Alae ‘Ula, or Hawaiian Common Gallinule (Gallinula galeata sandvicensis) with 927 individuals, and the Koloa Maoli, or Hawaiian Duck (Anas wyvilliana) with 931 individuals. All four species had positive trends over the long-term, but short-term and island specific trends were more variable, and in some cases negative. These results provide valuable information to help guide management of Hawaii’s threatened and endangered endemic waterbirds.