Endangered Species in the Pacific Islands

Hawaiian Stilt / Himantopus mexicanus knudseni  / Ae‘o (one standing tall)

	The Hawaiian stilt is a slender wading bird that grows up to 15 inches in length. It has a black back and white forehead, and is white below; the female has a tinge of brown on its back. This endangered species has very long pink legs and a long black bill. The Hawaiian subspecies differs from the North American stilt by having more black on its face and neck, and longer bill, tarsus, and tail.
Ae‘o - Photo credit USFWS

Habitat & Behavior:
Ae‘o use a variety of aquatic habitats but are limited by water depth and vegetation cover. Specific water depths of 13 cm (5 inches) are required for optimal foraging. Nest sites are frequently separated from feeding sites and stilts move between these areas daily. Nesting sites are adjacent to or on low islands within bodies of fresh, brackish, or salt water.

Feeding habitats are shallow bodies of water providing them with a wide variety of invertebrates and other aquatic organisms (worms, crabs, fish). They like to loaf around in open mudflats, sparsely vegetated pickleweed mats, and open pasture lands perhaps because visibility is good and. During the nesting period, incubating pairs may move between the nest site and a foraging area.

Stilts have a loud chirp that sounds like: kip kip kip. The female chirp is lower than the male’s.

Past & Present:
Stilts were historically known to be on all the major islands except Lana‘i and Kaho‘olawe. As with the other Hawaiian waterbirds, historic numbers are unknown. It is believed that there were about 1,000 of them in the late 1940s.

The Hawaiian stilt can still be found on all the major islands except Kaho‘olawe, but their numbers have not increased by much. It appears that the population has stabilized or slightly increased over the past 30 years. Stilt numbers have varied between 1,100 and 1,783 between 1997 and 2007, according to state biannual waterbird survey data, with Maui and O‘ahu accounting for 60-80% of them.

The main threats to the stilt and other waterbirds include the loss and degradation of wetland habitats and introduced predators.

The Hawaiian stilt can be seen at Hanalei National Wildlife Refuge on Kaua‘i, Kakahai‘a NWR on Moloka‘i, and Kealia Pond NWR on Maui, as well as other wetlands around the state.

Conservation Efforts:
The ae‘o was once a popular game bird, but waterbird hunting was banned in 1939. Since then, local landowners and government agencies have worked hand-in-hand to protect waterbirds and the habitat they depend on. The Hawaiian stilt gained further protection when the U.S. Fish and Wildlife Service listed it as an endangered species on October 13, 1970, and completed a recovery plan in 1985.