ʻAkepa

The ʻakepa (Loxops coccineus) is one of the smallest Hawaiian forest birds, at four inches long and weighing 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 gray 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 ʻakepa 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 ʻakepa cross-bill operates similarly to that in the North American crossbills (genus Loxia), but is much less obvious when the bill is closed.

ʻAkepa are usually found from 1,500 to 2,200 meters above sea level. They are non-territorial, and group male displays have often been observed in the beginning of the breeding season. They participate in mixed-species flocks during the non-breeding season. They are highly endangered.

History

ʻAkepa is a Hawaiian term meaning "agile", befitting their active foraging at branch tips.

The Hawaii ʻakepa 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 ʻiʻiwi (Vestiaria coccineus).

Taxonomy

The akepa (Loxops coccineus) is divided into three subspecies, only one of which, the Hawaiʻi ʻakepa, can be found today:

• Hawaii ʻakepa, Loxops coccineus coccineus
• Maui ʻakepa, Loxops (coccineus) ochraceus - extinct (1988)
• Oʻahu ʻakepa, Loxops (coccineus) wolstenholmei - extinct (1990s)

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 ʻakepa", but it is not the same species as the other ʻakepa (and is given the scientific name Loxops caeruleirostris).

Distribution and relatives

• Loxops coccineus coccineus: The Hawaii ʻakepa survives only in two or three locations, all on the island of Hawaii: one population in Hakalau Forest National Wildlife Refuge (on the Hamakua Coast of Mauna Kea), one in the upper forest areas of Kau (in the southern part of the island), and one on the northern slope of Hualālai (perhaps extirpated).

• Loxops coccineus wolstenholmei: The Oahu ʻakepa was found in large numbers until the 1890s. Immediately afterward, a sharp drop in its numbers was noted. Many feel that it had disappeared by the 1920s; however, scattered, unconfirmed reports were posted in the 1990s. This subspecies' male was brick red in coloration, while the female was dark gray.

• Loxops coccineus ochraceus: The Maui ʻakepa was found on the mountain of Haleakalā in east Maui. This population was detected at low numbers until 1992, when the last sighting was documented. There are still reports of green yellow birds flying in the remote reserve, so there may be individuals remaining, but this is very unlikely as dedicated intensive surveys have failed to confirm any Maui ʻakepa.

• Loxops caeruleirostris: The akeke’e, or Kauai ʻakepa, was once thought to be another subspecies of L. coccineus, but was evident in the 1990s that this bird was different in coloring, nesting, songs and degree of sexual dimorphism.

Diet

This species is highly dependent on ʻōhiʻa lehua trees and koa trees for food. Its bill is specialized for opening ʻōhiʻa 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 ʻakepa population declines. The lehua (or blossom) of the ʻōhiʻa tree provides a source of nectar that this bird consumes occasionally. The koa tree's cracked bark serves as a home for many insects and arthropods that the ʻakepa finds delectable.

Breeding

These birds have a breeding season in spring. The Hawaii ʻakepa is the only obligate cavity-nester in Hawaii. There are no cavity-making birds in Hawaii (another honeycreeper, the ʻakiapolaʻau, drills small holes and excavates bark, but does not make holes large enough for ʻakepa nests). Thus, the ʻakepa must find naturally occurring cavities in the trunks and branches. Such cavities are generally found only in very large, old trees, making the ʻakepa 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.

Threats

Two of the three subspecies of ʻakepa (Loxops coccineus) are extinct or probably extinct. As of 2000, about 14,000 Hawaiʻi ʻakepa remained. They were listed as an endangered species in 1975.

Disease

Surviving ʻakepa live only on the island of Hawaii, and only in old growth forest above 1,200 metres (3,937 ft) elevation. This is a sign that avian malaria and avian pox have played a role in killing off populations of ʻakepa at lower elevations. These introduced diseases are implicated in more than 20 bird extinctions in Hawaii since 1826, when the first mosquito (Anopheles species) was introduced to the islands. Disease continues to be a threat, and could result in extinction of the ʻakepa if Hawaiian 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, ʻakepa rely on old-growth ʻōhiʻa and koa forests for nesting. Although the largest populations of ʻakepa 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 experiments 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 ʻakepa as of 2010.

Mammals

Alien predators can be highly dangerous to native birds in dry and mesic forest. However, there is no evidence that rat predation is important for ʻakepa 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 ʻakepa 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 ʻakepa for food; white-eyes have increased exponentially in the core of the ʻakepa range since 2001 (Camp et al. 2009, Freed and Cann 2009), where ʻakepa 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, ʻakepa 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 species requires active research and management in order for it to survive existing and emerging threats.

References

1. ↑ BirdLife International (2013). "Loxops coccineus". IUCN Red List of Threatened Species. Version 2013.2. International Union for Conservation of Nature. Retrieved 26 November 2013. 

• Camp, R.J, T.K. Pratt, P.M. Gorresen, J.J. Jeffrey, and B.L. Woodworth. 2009. Passerine Bird Trends at Hakalau Forest National Wildlife Refuge, Hawaii. http://www.uhh.hawaii.edu/hcsu/publications.php
• Freed, L. A., T. M. Telecky, W. A. Tyler and M. A. Kjargaard. 1987. Nest site variability in the Akepa and other cavity-nesting birds on the island of Hawai'i. Elepaio: 47(8).
• Freed LA, Medeiros MC, and Bodner GR. 2008. Explosive increase in ectoparasites in Hawaiian forest birds. J Parasitol. 94(5):1009-21.
• Freed LA and Cann RL. 2009. Negative Effects of an Introduced Bird Species on Growth and Survival in a Native Bird Community. Current Biology.
• Fretz, J. S. 2002. Scales of food availability for an endangered insectivore, the Hawaii Akepa. The Auk 119(1).

External links

Wikispecies has information related to: Loxops coccineus

• Species factsheet - BirdLife International