Ou

Psittirostra psittacea

Description

The ou, Psittirostra psittacea, is one of the largest Hawaiian honeycreepers, measuring about 6.4 in (16.2 cm) long. Males have bright yellow heads clearly separated from dark green backs, light green underparts, and gray breasts. Its iris is hazel, the feet pinkish, and the beak pink to straw colored. The green-headed females are olive green above with grey throats, grayish-white bellies, and white undertail coverts. The distinctive parrotlike bill is straw colored in both sexes.

Behavior

The diet of the ou consists of fruits, flowers, and insects. Dietary items include guava berries, nectar of ohia (Metrosideros collina ) flowers, wild mulberry, mamaki (Pipturus sp.) berries, oranges, bananas, peaches, and the tender leaves of lapalapa (Cheirodendron sp.), mountain apple, olana, and opuhe (Utera sp.). It changes elevations seasonally in search of food, and the birds may forage in loose flocks. It feeds large numbers of caterpillars to its young. Adults seem to prefer the fruit of the ieie (Freycinetia arborea ). The nest, eggs, and unfledged young have never been observed, but females with enlarged ovaries have been trapped from late March to mid May, and a female was observed carrying a twig in March. Young have been seen in May and June, suggesting a March to May breeding season. The ou may pair for life. The ou appears to move to lower elevations during the day and return to higher forest elevations at night. Daily search for food may include a range as long as 3.5 mi (5.5 km). These birds may also migrate between islands to avoid storms.

Habitat

The only current habitat for the ou seems to be middle-elevation ohia (Metrosideros collina ) forests at heights between about 3,000 and 5,000 ft (914 and 1,524 m). It uses standing snags, possibly for nesting, in the old to mature growth of ohia forests. The presence of bogs with lichens, mosses, grasses, violets, and sedges seems to be a requirement for nest building. The ohia forests are about 50 ft (15.2 m) tall with a substory of lapalapa trees in which the birds frequently perch. Numerous meandering mountain streams dissect the area creating narrow knife-like ridges, cliffs, ledges, and steep inclines to adjoining streams.

Distribution

The ou was common in the wet, mesic, and dry-forests on all six Hawaiian islands, especially on Kona, eastern Hawaii, and Kohala. Occasionally it was found even in drier forests. About 400 ou remain on the island of Hawaii, in mid-elevation forests east of Mauna Kea and Mauna Loa. A small number of ou, almost certainly less than 75, inhabit the southern, more inaccessible portions of Alakai Swamp on Kauai. It is presumed to be extinct elsewhere in its original range.

Threats

The main factor in the decline of Hawaii's forest birds has been deforestation. Hawaii's forests were once extensive but have been drastically reduced by logging and conversion to croplands and pasture. Today, most of the forests below 2,600 ft (800 m) have been converted to agricultural or urban uses, and the upper elevation koa (Acacia koa ) forests on Hawaii have been severely cutback. Grazing and browsing animals have also modified remnant forests at upper elevations. Widespread dieback of ohia, Hawaii's most common native forest tree, has diminished large portions of ou habitat on the island of Hawaii, and additional areas may be threatened. The cause of death for many of these trees has not been determined. In addition to deforestation, Hawaiian forest birds are very vulnerable to disease. Avian diseases pox and malaria, spread by mosquitoes introduced to the islands in the 1820s, have been the most damaging. Other introduced insects, such as parasitic wasps and predaceous ants, have eliminated some native insects that served as food for the birds.

Conservation and Recovery

Recovery of the ou and other forest birds will depend on restoring habitat and obtaining essential habitat areas as sanctuaries. In late 1985, the U.S. Fish and Wildlife Service (FWS), together with the Nature Conservancy and the state of Hawaii, purchased 8,300 acres (3,360 hectares) of native forest on the island of Hawaii. It marked the first phase of the proposed establishment of a 33,500-acre (13,560-hectare) Hakalau Forest National Wildlife Refuge, which is designed primarily to preserve the habitat of endangered forest birds. The refuge is located on the northwestern slope of Mauna Kea and contains some of the best koa-ohia forests remaining on the islands. Another 400-acre (162-hectare) parcel was acquired in 1988 by the Nature Conservancy and sold to FWS for inclusion in the refuge.

Contacts

Pacific Joint Venture
300 Ala Moana Boulevard, Room 3-122
P.O. Box 50167
Honolulu, Hawaii 96850-0056
(808) 541-2749

U.S. Fish and Wildlife Service
Regional Office, Division of Endangered Species
Eastside Federal Complex
911 N.E. 11th Ave.
Portland, Oregon 97232-4181
(503) 231-6121
http://pacific.fws.gov/

References

Berger, A.J. 1972. Hawaiian Birdlife. The University Press of Hawaii, Honolulu.

U.S. Fish and Wildlife Service. 1982. The Hawaii Forest Bird Recovery Plan. U.S. Fish and Wildlife Service, Portland.