Hawaiian coots (Fulica alai) historically occurred on all of the main Hawaiian Islands except Lana'i and Kaho`olawe, which lacked suitable wetland habitat . They are known to have always been most numerous on Kaua'i, Maui, and O'ahu, but there are no historical population estimates. The population was low enough in 1939 to warrant establishment of a permanent hunting ban . In the 1950s it was considered to be on an extinction trajectory. Fewer than 1,000 birds were thought to remain in the late 1960s.
Hunting was a significant threat until outlawed in 1939 . Habitat is now the primary cause of endangerment. For example, Ka‘elepulu Pond on O‘ahu, supported nearly 1,000 coots until it was dredged and surrounded by mowed lawns and cement in the 1940s as part of the Enchanted Lake subdivision . The current population is much smaller. Conversely, the species has expanded into unusual habitats such as sewage-treatment plants at Kailua-Kona, Hawai'i; Lana‘i City, Lana‘i; and Kuilima, O‘ahu .
Biannual surveys indicate short-term population fluctuations associated with rainfall, and an overall population increase between 1967 and 2003, but the recent population trend (1998-2003) has generally been downward . The 2005 population was estimated at about 2,100 birds with 80% of birds on Kaua’i, O'ahu, and Maui. All the main Hawaiian Islands except Kaho`olawe are currently occupied.
 U.S. Fish and Wildlife Service. 2005. Draft Revised Recovery Plan for Hawaiian Waterbirds, Second Draft of Second Revision. U.S. Fish and Wildlife Service, Portland, Oregon. 155 pp.
 Brisbin, I. L., Jr., H. D. Pratt, and T. B. Mowbray. 2002. American Coot (Fulica americana) and Hawaiian Coot (Fulica alai). In The Birds of North America, No. 697 (A. Poole and F. Gill, eds.). The Birds of North America, Inc., Philadelphia, PA.