Oahu Elepaio Chasiempis ibidis Scientific name definitions

The elepaios are a group of three closely related species endemic to the Hawaiian Islands, and the only members of the monarch flycatcher family (Monarchidae) in the United States. Elepaios occur on the islands of Hawaii, Oahu, and Kauai, but are absent from the other islands, even in the fossil record (1 James, H. F. and S. L. Olson. (1991). Descriptions of thirty-two new species of birds from the Hawaiian Islands: Part 2: Passeriformes. Ornithological Monographs 46. Close , 2 Burney, D. A., H. F. James, L. P. Burney, S. L. Olson, W. Kikuchi, W. L. Wagner, M. Burney, D. McCloskey, D. Kikuchi, F. V. Grady, R. Gage II and R. Nishek. (2001a). Fossil evidence for a diverse biota from Kaua'i and its transformation since human arrival. Ecological Monographs 71 (4):615-641. Close ). The form on each island was originally described as a separate species, but they were later lumped (3 Bryan, Jr., E. H. and Jr. Greenway, J. C. (1944b). Check-list of the birds of the Hawaiian Islands. Bulletin of the Museum of Comparative Zoology 94:92-140. Close ), and this taxonomy was followed by the American Ornithologists' Union for many years (4 American Ornithologists' Union (1998). Check-list of North American Birds. Seventh edition. American Ornithologists' Union, Washington, DC, USA. Close ). In 2010, based on a combination of genetic, morphological, and behavioral evidence (5 Conant, S., H. D. Pratt and R. J. Shallenberger. (1998). Reflections on a 1975 expedition to the lost world of the Alaka'i and other notes on the natural history, systematics, and conservation of Kaua'i birds. Wilson Bulletin 110 (1):1-22. Close , 6 VanderWerf, E. A. (2007). Biogeography of 'Elepaio: Evidence from inter-island song playbacks. Wilson Journal of Ornithology 119 (3):325-333. Close , 7 VanderWerf, E. A., L. C. Young, N. W. Yeung and D. B. Carlon. (2010). Stepping stone speciation in Hawaii's flycatchers: Molecular divergence supports new island endemics within the Elepaio. Conservation Genetics 11 (4):1283-1298. Close ), the American Ornithologists' Union approved a petition to split the Elepaio into three species once again (8 Chesser, R. T., R. C. Banks, F. K. Barker, C. Cicero, J. L. Dunn, A. W. Kratter, I. J. Lovette, P. C. Rasmussen, J. V. Remsen Jr., J. D. Rising, D. F. Stotz, and K. Winker (2010). Fifty-first supplement to the American Ornithologists' Union Check-list of North American Birds. Auk 127: 726–744. Close ).

The three elepaio species differ in plumage coloration and vocalizations, and in some aspects of their ecology, including habitat use (9 VanderWerf, E. A. (2012a). Ecogeographic patterns of morphological variation in Elepaios (Chasiempis spp.): Bergmann's, Allen's, and Gloger's rules in a microcosm. Ornithological Monographs 73:1-34. Close , 10 VanderWerf, E. A. (2012b). Evolution of nesting height in an endangered Hawaiian forest bird in response to a non-native predator. Conservation Biology 26 (5):905-911. Close ). Elepaios on all islands exhibit a two-year delay in plumage maturation in both sexes, but the subadult plumage differs among islands in degree of similarity to adult plumage (11 VanderWerf, E. A. (2001b). Two-year delay in plumage maturation of male and female 'Elepaio. Condor 103 (4):756-766. Close , 9 VanderWerf, E. A. (2012a). Ecogeographic patterns of morphological variation in Elepaios (Chasiempis spp.): Bergmann's, Allen's, and Gloger's rules in a microcosm. Ornithological Monographs 73:1-34. Close ). Sexual dimorphism in throat color is more pronounced on younger islands (Hawaii) than on older islands (Kauai).

The Oahu Elepaio is by far the rarest of the three elepaio species. It has declined seriously in the last few decades and now numbers only about 1,200 individuals (12 VanderWerf, E. A., M. T. Lohr, A. J. Titmus, P. E. Taylor and M. D. Burt. (2013). Current distribution and abundance of the O'ahu 'Elepaio (Chasiempis ibidis). Wilson Journal of Ornithology 125 (3):600-608. Close ), and is listed as Endangered by the U.S. Fish and Wildlife Service (13 Fish, U.S. and Wildlife Service. (2006b). Final revised recovery plan for Hawaiian forest birds. Portland: U.S. Fish and Wildlife Service. Close ). Nest depredation by the non-native Black Rat (Rattus rattus) is the greatest threat to the Oahu Elepaio. Efforts to control rats have resulted in some local population increases (14 VanderWerf, E. A. and D. G. Smith. (2002). Effects of alien rodent control on demography of the O'ahu 'Elepaio, an endangered Hawaiian forest bird. Pacific Conservation Biology 8 (2):73-81. Close , 15 VanderWerf, E. A. (2009). Importance of nest predation by alien rodents and avian poxvirus in conservation of Oahu Elepaio. Journal of Wildlife Management 73 (5):737-746. Close , 16 VanderWerf, E. A., S. M. Moscher, M. D. Burt, P. E. Taylor and D. Sailer. (2011a). "Variable efficacy of rat control in conserving Oahu Elepaio populations." In Island invasives: Eradication and management, edited by C. R. Veitch, M. N. Clout and D. R. Towns, 124-130. Gland: IUCN. Close ). Remarkably, the Oahu Elepaio is evolving in response to depredation by building its nests higher off the ground where they are less accessible to rats (10 VanderWerf, E. A. (2012b). Evolution of nesting height in an endangered Hawaiian forest bird in response to a non-native predator. Conservation Biology 26 (5):905-911. Close ). The elepaios are affected by introduced mosquito-borne diseases, but have greater immunity than most of the Hawaiian honeycreepers, and in some areas they are found at low elevations (17 VanderWerf, E. A., M. D. Burt, J. L. Rohrer and S. M. Mosher. (2006). Distribution and prevalence of mosquito-borne diseases in O'ahu 'Elepaio. Condor 108 (4):770-777. Close ).

Unusual among native Hawaiian birds, elepaios are adaptable in their habitat use and the Oahu Elepaio in particular often inhabits disturbed secondary forest dominated by non-native plant species. Elepaios are versatile foragers and use a remarkable variety of behaviors to search for and capture prey at all heights and on all substrates in the forest, including the ground, tree trunks, branches, leaves, and in the air.

Elepaios are long-lived, sedentary, and occupy the same small territory throughout the year, and individuals can be found in the same location year after year. Banded Oahu Elepaios have lived to be at least 22 years old. Younger birds in subadult plumage are sexually mature, but are subordinate to older birds, often acting as floaters until they acquire their own territory.

Bold and inquisitive, elepaios often investigate and even follow hikers, holding their tail cocked up in a curious posture, and can be attracted easily by squeaking. The elepaios are important in the mythology of the Hawaiian people, and are considered the guardian spirit of Hawaiian canoe makers.