The ?Elepaio (Chasiempis sandwichensis) is a monarch flycatcher endemic to Hawaii. and the only species of its genus. It inhabits the Big Island, O?ahu and Kaua?i in no less than 5 different subspecies. Being one of the most adaptable native birds of the archipelago, no subspecies have yet become extinct, though two have become quite rare nowadays.
The ?elepaio is the first native bird to sing in the morning and the last to stop singing at night; apart from whistled and chattering contact and alarm calls, it is probably best known for its song, from which derives the common name: a pleasant and rather loud warble which sounds like e-le-PAI-o or ele-PAI-o. It nests between January and June.
In Hawaiian tradition, the ?elepa'io was among the most celebrated of the birds. It is associated with a number of significant roles in culture and mythology. Chiefly, it helped canoe-builders to select the right koa tree to use for their canoe. The "?elepaio is a bold and curious little bird, and thus it was attracted to humans whom it found working in its habitat, and it quickly learned to exploit feeding opportunities created by human activity, altering its behavior accordingly - which incidentally made it even more conspicuous.
For example, it followed the canoe builders through the dense vegetation, watching them as they searched for suitable trees. They considered it their guardian spirit, an incarnation of their patron goddess Lea, because if the bird pecked at a fallen tree, it was a sign that the tree was riddled with burrowing insects and thus not good anymore, but when the bird showed no interest in a tree, it indicated that the wood was suitable. This is the origin of the ancient Hawaiian proverb, ?U? ?elepaio ?ia ka wa"?a ("The canoe is marked out by the ?elepaio").
In addition, the bird was well-liked for another reason - it was good to eat, and not subject to kapu restrictions. Due to its insectivorous habit, farmers believed the ?elepaio to be the incarnation of Lea's sister goddess, Hina-puku-?ai, who protected food plants and was a patron of agriculture.
As the bird was just as useful - perhaps even more useful - to humans alive as it was as food, overhunting of populations, while theoretically permissible under the kapu laws, did not usually occur. Additionally, although deforestation for agriculture destroyed some habitat, the ?elepaio managed to adapt well to the initial settlement. Thus, its population was large enough to withstand the additional pressures that came about with Western colonization of the islands.
The photograph is of a female Chasiempis sandwichensis ridgwayi (Volcano ?Elepaio). The 3 subspecies on Big Island differ in their ecological requirements and head coloration (see also Gloger's Rule).
- Big Island
- Chasiempis sandwichensis sandwichensis, the Kona ?Elepaio. It differs from the Volcano subspecies by having the forehead and the supercilium whitish with some rusty feathers. It inhabits the mesic forest characterized by koa and ?ohi?a; its population seems to be stable at about 60.000-65.000.
- C. s. ridgwayi, the Volcano ?Elepaio. This is the most common subspecies today, with a population of around 100.000-150.000, or more than half of the total number of ?elepaio. It is a bird of the rainforest, which on Hawai"?i is characterized by ?ohi?a and h?pu?u.
- C. s. bryani, the Mauna Kea ?Elepaio, is only found in the dry mamane-naio forest on the leeward slopes of Mauna Kea. It has the entire head heavily washed with white. Due to destruction of most of its habitat, it is the rarest Big Island subspecies, with a population of 2.000-2.500 birds.
- C. s. ibidis, the O?ahu ?Elepaio, is nowadays restricted to an area of c.47 kmē in the Ko?olau and Wai?anae ranges, where a fragmented and declining population of 1.200-1.400 birds occurs. It is listed as endangered; Plasmodium falciparum malaria and avian pox are widespread in the population and although it appears to have weathere the worst of it, it is still declining from these diseases . This subspecies looks very similar to ridgwayi, but the white underside extends to the flanks and further up the breast, and the upperside - especially the head - is more rust-colored.
Birds of these 4 subspecies undergo a complex series of plumage stages during the 2 years until they reach maturity. This reduces social conflicts, apparently by visually designating birds not yet sexually mature.
- C. (sandwichensis) sclateri, the Kaua?i ?Elepaio, is most probably is a distinct species. Its population numbered 40.000 around 1970, but declined by half in the 1990s. Whether this fluctuation is natural and thus the birds' numbers will rebound or whether it signifies a novel threat remains to be seen. This is the most distinct ?elepaio; adult birds have their head and back grey, with a white supercilium, a rusty-red breast and a white underside. Young birds are uniformly rusty above and white below. Wings and tail are alike in all subspecies, but the young individuals of sclateri have the white stippling of the wings replaced by rusty coloration too.
Uniquely among Hawaiian passerines, the distribution of the ?elepaio is peculiarly discontinuous. It does not - and judging from the lack of fossil remains, apparently never did - occur on Maui Nui or its successor islands. If this assumption is correct, the reasons are unknown at present. However, the strange "flycatcher finches", extinct honeycreepers of the genus Vangulifer, are only known to have inhabited Maui and probably evolved on Maui Nui. There, they probably filled the same ecological niche as the ?elepaio did on the other islands. Competition from Vangulifer may thus have prevented a successful colonization of Maui Nui by Chasiempis.