Habitat
Oahu Elepaio occur mainly in mixed-species forest with a tall canopy and a well-developed understory. They are most common in river and stream valleys, which are highly disturbed habitats dominated by non-native plants.
Back to topFood
Oahu Elepaio eat spiders and insects, including beetles, flies, caterpillars, moths, katydids, and lacewings. When foraging they climb on vertical trunks, cling upside down to branches and leaf clusters like a chickadee, hop on the ground like a thrush, and pursue insects in flight. Because Oahu Elepaio occur in areas dominated by non-native plants, they eat introduced insects (including mosquitoes and fruit flies) in addition to native species.
Back to topNesting
Nest Placement
Placed in a branch fork or on a horizontal branch in both native and introduced trees. The average nest height increased 50% between 1996 and 2011—from 8 to 12 meters (26 to 39 feet)—in response to nest depredation by black rats.
Nest Description
A finely woven open cup made with fine grasses, rootlets, thin bark strips, and spider silk. The outside of the nest is often camouflaged with lichen, moss, liverwort, or tree fern hair.
Nesting Facts
| Egg Description: | White with dark reddish-brown markings. |
Behavior
Oahu Elepaio are agile, acrobatic birds. They hop or flit between twigs and branches, cling to vertical surfaces using strong legs and feet, and hang upside down from branches and leaf clusters. They often cock their long tail upward when perched, and use it as a rudder to quickly change direction in flight. While foraging, Oahu Elepaio sometimes flick their wings and fan their tail to expose white spots—perhaps to startle and flush prey.
Oahu Elepaio are monogamous and pairs defend a territory together year-round. They usually mate for life, but a bird will take a new mate if the previous one dies. Both sexes build the nest, incubate the eggs, and feed the nestlings and fledglings. However, females are more likely to be preyed upon at the nest by black rats, resulting in more males in the population than females. Young birds stay in their home territory for up to 10 months and form family groups with their parents, which eventually evict them from the area when the next breeding season starts. Individuals do not acquire full adult plumage until after two years of age, but may begin breeding after just one year.
Back to topConservation
The International Union for Conservation of Nature lists Oahu Elepaio's conservation status as Vulnerable due to a very small population size (estimated at 1,261 mature individuals following surveys in 2011–2012) and a declining population trend. The U.S. Fish and Wildlife Service listed Oahu Elepaio as Endangered in 2000. Nest predation by introduced black rats is the main threat to Oahu Elepaio. Between 1996 and 2011, the average Oahu Elepaio nest height incrased from 8 to 12 meters (26 to 39 feet), helping to make the nests less accessible to rats, but active rat control by conservation biologists remains the foundation of efforts to reduce nest predation and increase Oahu Elepaio nesting success. Elepaio are less affected by avian malaria than other native Hawaiian forest birds.
Back to topCredits
BirdLife International. 2023. Chasiempis ibidis. The IUCN Red List of Threatened Species 2023: e.T22736423A224391681. https://dx.doi.org/10.2305/IUCN.UK.2023-1.RLTS.T22736423A224391681.en.
Floyd, T. (2025). Field Guide to the Birds of the United States and Canada. Eighth edition. National Geographic Society, Washington, D.C.
Pratt, H. D., P. L. Bruner, and D. G. Berrett (1987). A Field Guide to the Birds of Hawaii and the Tropical Pacific. Princeton University Press, Princeton, NJ, USA.
Raine, H. and A. F. Raine (2020). American Birding Association Field Guide to Birds of Hawai'i. Scott & Nix, Inc. New York, NY, USA.
VanderWerf, E. A. (2020). Oahu Elepaio (Chasiempis ibidis), version 1.0. In Birds of the World (P. G. Rodewald, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.elepai4.01