O'ahu Creeper

Paroreomyza maculata

Description

Male O'ahu creepers, Paroreomyza maculata, are small birds, olive-green above and golden-yellow below. Females and immatures are gray above, yellowish-white below with prominent white wing bars. O'ahu creeper has dark lores with a prominent pale superciliary stripe. The bill is straight, in contrast to the decurved bill of the similar O'ahu 'amakihi. Often mistaken for the 'Amakihi, P. maculata, can also be distinguished by, the dark stripe beginning with the lores extending past the eye on the creeper and not on the 'Amakiki, and the lighter forehead and pale lower mandible of the creeper.

Behavior

Relatively little is known about O'ahu creeper food habits. All known Hawaiian creepers obtain most of their predominantly insect food from the trunks and limbs of forest trees and shrubs. Caterpillars, spiders, myriopods, slugs, beetles, and moths are typical food. Field observations in recent sightings indicate that these birds regularly move up and down trunks and limbs, often in "creeper like" fashion, pecking and probing at and under bark in search of insect food. They tend to remain within the interior branches and trunk area, rather than feeding in the canopy. Some recent observations have also been made in the vicinity of slime fluxes on koa trees, presumably a site where insects are attracted. No observations have been recorded of the species feeding on nectar.

Based upon observations of nests and a single observation of a bird carrying nest material, a January-April nesting period is likely. With the exception of a nest found with two eggs, nothing is known about other reproductive characteristics of the species.

There is no evidence to indicate that O'ahu creeper is migratory. However, several of the recent sightings have been on trails that are frequently traveled by birders. The infrequency of sightings on these popular trails suggests that birds of this species may move in and out of these areas with some regularity.

This bird's song is not known, but their call has been described as "chip." O'ahu creeper sightings have been recorded only during daylight hours. Virtually nothing is known regarding seasonal variation in its habitats.

Habitat

All reliable sightings of O'ahu creeper in the last forty years have been at elevations between 1,000-2,300 ft (300-700 m), typically in wet and mesic forest dominated by ohi'a (Metrosideros) and koa (Acacia). Historically, the native forest of the species was entirely evergreen, however, today there are areas that have been invaded by deciduous exotics. Most sightings have been on ridge trails, running generally southwest to northeast along mountainous valleys. This fact probably reflects the relative accessibility of these trails, not the preferred distribution of the species. Three sightings during recent intensive surveys within Ko'olau Range valleys were all on valley slopes between the ridge trails and valley floor. Forest understory in areas where birds have been sighted includes various native shrubs and fern. No specimens have been sighted recently along valley floors where exotic trees typically predominate.

Only two O'ahu creeper nests have been reported in the literature. An incomplete nest was found on January 29, 1901 and a second nest, with two eggs, was collected the following day. Both were found in the Wai'anae mountains. The first nest was on the top of a small bush and was made of club moss, lichens, spider webs, leaves and rootlets. The second nest was 20 ft (6 m) above the ground, in a kukui tree, and was made of moss and rootlets.

Distribution

During the 1890s, creepers were reported to be abundant on all islands except O'ahu. Due to the similar appearance of O'ahu creeper and the more common Loxops virens chloris, several sightings of the species are considered questionable. During the course of extensive mountain range surveys in 1977-78, only three certain and one possible sighting were made, all on ridge trails or valley slopes in the south-central Ko'olau range. Since that time, only one additional sighting, of two immature O'ahu creeper, has been reported. Given the distribution of recent sightings and the condition of suitable habitat, the species present range may possibly include all valleys and ridges above 1,000 ft (300 m) in the Ko'olau Range, particularly the central portion, and a smaller portion of relatively undisturbed forested habitat in the central Wai'anae Range. The last confirmed sighting of this bird was in 1991 in Halawa Valley; an unconfirmed sighting in the northern Koolaus was made in 1997.

Threats

Habitat degradation and destruction, human exploitation, predation, avian diseases, and competition with introduced species are all factors that have contributed to the decline of the O'ahu Creeper and many other native forest birds.

The population may be limited in part by its very low numbers and subsequent limited interaction of potential breeding pairs. Some valleys within its present and former range have been severely altered by construction of highways, power lines, urbanization and the use of heavy equipment associated with these activities. Military training activities also disturb O'ahu's forest birds and their habitat, due to ordnance-related fires, accelerated invasion of exotic plants and low altitude helicopter flights.

With most of the forested habitat confined to elevations below 3,000 ft (900 m), avian competitors and malarial hosts probably contributed substantially to the rapid decline of O'ahu creeper in the last 100 years. The Japanese white-eye probably represents a significant historic and present threat to the species. White-eyes compete for food and shelter and provide a host for avian malaria and avian pox. These disease organisms are believed to explain the virtual absence of creepers with similar habits at elevations below 3,000 ft (900 m) on other Hawaiian islands. The obligate vector for malaria and the facultative vector for pox in these areas is the mosquito. Predation from mongooses, rats and feral cats may also be an important limiting factor

Conservation and Recovery

O'ahu creeper remains one of the most neglected endangered species with regard to both research and conservation. The rarity of the species and its close resemblance to the relatively common O'ahu race of 'amakihi (Hemignathus virens chloris ), have lead to much confusion as to the true status of the species. A first step towards recovery of this creeper would be to locate a population, towards which recovery actions could be applied. Recovery actions would include identifying and securing habitat through land acquisition, cooperative agreement, easement, zoning, or other means, and improving essential habitat; research on the species' biology; and captive breeding. Habitat improvement would include controlling exotic plants, feral pigs, rats, and mosquitoes. Much of O'ahu creeper's habitat lies within conservation districts or military reserves, but otherwise it receives no special protection.

Contact

Regional Office of Endangered Species
U. S. Fish and Wildlife Service
Eastside Federal Complex
911 N. E. 11th Ave.
Portland, Oregon 97232
http://pacific.fws.gov/

Reference

U. S. Fish and Wildlife Service. 18 January 2000. "O'ahu Creeper / Paroreomyza maculata / O'ahu 'Alauahio."Threatened and Endangered Animals in the Pacific Islands. http://pacific.fws.gov/pacific/wesa/creepoahu.html.