| ʻĀkepa | |
|---|---|
| Conservation status | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Aves |
| Order: | Passeriformes |
| Family: | Drepanididae |
| Genus: | Loxops |
| Species: | L. coccineus |
| Binomial name | |
| Loxops coccineus (Gmelin, 1789) |
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The ʻAkepa (Loxops coccineus) is one of the smallest Hawaiian forest birds, at four inches/10 grams. Found only in high elevation old growth rainforest, these nonmigratory passerines have rounded heads, black eyes, and black wings and tail. Adult males sport one of the most brilliant orange colors found in any bird, a plumage which takes four years to develop. Females are greenish gray on back, lighter grey on front, with varying amounts of yellow and sometimes pale orange on the breast and belly. Juveniles appear similar to females, though are generally duller in color.
All 'Akepa have an unusual cross-bill. When closed, the upper bill tip slightly overlaps the lower bill tip to one side (this cannot be seen in the field). When opening the bill, as in prying open leaf buds to extract small caterpillars, the bills swing dramatically sideways, and this is easily seen in the hand. Some birds cross one way, and some the other, apparently randomly. The Akepa cross-bill operates similarly to that in the North American Crossbills (genus Loxia), but is much less obvious when the bill is closed.
Akepa are usually found from 1,500 to 2,200 meters above sea level. They are non-territorial, and group male displays have been often observed in the beginning of the breeding season. They participate in mixed-species flocks during the non-breeding season. They are highly endangered.
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'Akepa is a Hawaiian term meaning 'agile,' befitting their active foraging at branch tips.
The Hawaii Akepa was first collected by western science during Captain James Cook's third voyage around the world. Several specimens were collected, as well as feather leis (necklaces resembling strings of flowers) constructed by Hawaiian artisans. The specimens were classified when brought back to England several years later. The Latin name of the bird, Loxops coccineus means "crossed" (Loxops) and "red" (coccineus). The word "coccineus" is also used in another Hawaiian bird the I'iwi, Vestiaria coccineus.
The Akepa (Loxops coccineus) is divided into three subspecies, only one of which, the Hawaii Akepa, can be found today:
There is much speculation that the three "subspecies" above are (were) in fact three distinct species, based on geographic isolation and differences such as color and nesting location.
The ‘Akeke‘e is sometimes called the "Kauai Akepa," but it is not the same species as the other Akepa (and is given the scientific name Loxops caeruleirostris).
This species is highly dependent on 'Ohi'a -lehua trees and Koa trees for food. Its bill is specialized for opening 'Ohi'a-lehua leaf buds in search of small caterpillars. Fretz (2002) suggests that this food source is only found in old-growth Hawaiian forests and could be one factor in Akepa population declines. The lehua (or blossom) of the 'Ohi'a tree provides a source of nectar that this bird consumes occasionally. Koa tree's cracked bark serves as a home for many insects and arthropods that the Akepa find delectable.
These birds have a breeding season in spring. The Hawaii Akepa is the only obligate cavity-nester in Hawaii. There are no cavity-making birds in Hawaii (another honeycreeper, the Akiapola'au, drills small holes and excavates bark, but does not make holes large enough for Akepa nests). So, the Akepa must find naturally occurring cavities in the trunks and branches. Such cavities are generally found only in very large, old trees, making the Akepa an old-growth obligate. Large courtship groups have been observed during the breeding season, which is curious because this species makes permanent bonds. Another anomaly is the fact that for such a small bird, it does not lay many eggs - usually one or two, instead of the three to five of other similarly sized species.
Two of the three subspecies of Akepa (Loxops coccineus) are extinct or probably extinct. As of 2000, about 14,000 Hawai'i 'Akepa remained. They were listed as an endangered species in 1975.
Disease
Surviving Akepa live only on the island of Hawaii, and only in old growth forest above 4000' elevation. This is a sign that avian malaria and avian pox have played a role in killing off populations of Akepa at lower elevations. These introduced diseases are implicated in more than 20 bird extinctions in Hawaii since 1826, when the first mosquito was introduced to the islands. Disease continues to be a threat, and could result in extinction of the Akepa if the Hawaii climate continues to warm (or if new bird diseases or mosquito species are allowed to invade the islands).
Old growth deterioration
Due to their need for tree cavities, Akepa rely on old-growth Ohia and Koa forests for nesting. Although the largest populations of Akepa live within protected lands, large trees appear to be falling faster than they are replaced. It is unclear how management can deal with this in the medium-term, except by use of artificial nest boxes. Past experiment with nest boxes (Freed et al., 1987) have shown that birds will occasionally use them, with high nesting success. There is no ongoing research or use of nest boxes for Akepa as of 2010.
Mammals
Alien predators (such as rats) can be highly dangerous to native birds in dry and mesic forest. However, there is no evidence that rat predation is important for in Akepa or other wet-forest birds, perhaps due to the size of trees making it unlikely for a rat to chance upon a nest. Cattle, pigs, and other ungulates cause severe habitat degradation in native forests; however, this is more of a long-term threat for Akepa than a short-term threat, because canopy trees can survive for some time after ungulates have destroyed lower layers of the forest.
Emerging threats
Two new threats have been identified since 2000: alien birds and ectoparasites. Invasive birds such as the Japanese White-eye may compete with the Akepa for food; White-eyes have increased exponentially in the core of the Akepa range since 2001 (Camp et al. 2009, Freed and Cann 2009), where Akepa and other native birds have declined significantly since 1999, according to the Hawaii Forest Bird Survey (Camp et al. 2009) and banding data (Freed and Cann 2009). Disturbingly, Akepa and other native species have shown signs of starvation and runty nestlings, as well as declining population during this time.
Ectoparasites such as lice were uncommon in this area before 2003, but increased in epidemic proportion pattern from 2003-2006 (Medeiros et al. 2008). The origin of these ectoparasites is unknown, however they appear to be harming birds, as infested birds had feathers in poor condition.
There is no research currently ongoing on either of these threats (as of 2010). This is a species that requires active research and management in order for it to survive existing and emerging threats.