Kauai 'O'o

Moho braccatus

Description

The male and female Kauai 'o'o, Moho braccatus, are very similar in appearance and color, the only particular difference being that the female is slightly smaller. The top of the head is black with a faint gloss; the feathers are ashy grey along the shaft everywhere but at the tip. A few bristly feathers on the right and left of the forehead are ashy white. Some small, whitish, bristly feathers occur over the eye like the remains of a superciliary stripe, and the lores are deep black without any gloss. Feathers of the throat and foreneck are black, with a whitish bar before the tip. Feathers of the back and abdomen of the adult are a dark, smoky brown, with narrow, grayish shaft lines. In young birds, the abdomen is grayish olive and the shaft line is less developed. The feathers of the vent and under tail coverts are a rufus brown, while the rump and upper tail coverts are a uniform brown. Wings and tail feathers are a uniform black, the former are inwardly pure white. The brownish axillary tufts are not conspicuously developed. The tibiae is golden yellow in adults and blackish in juveniles. The iris is yellowish white in adults and more grayish in juveniles. The bill and feet are black with a grayish tinge, while the soles of the feet are a pale yellow. The dimensions of the Kauai 'o'o fall within the following ranges: total length between 7.5 and 8.5 in (19 and 21.5 cm), wing length between from 3.8 to 4.1 in (9.5 to 10.5 cm), tail length between 3.5 and 4 in (9 and 10 cm), the culmen between 1.1 and 1.2 in (2.7 and 3 cm), and the tarsus between 1.05 and 1.14 in (2.67 and 2.9 cm).

Behavior

The Kauai 'o'o was observed annually from 1971 to 1984, a period in which most of the information known about this species was gleaned. Active nests were found in 1971-73. The breeding season indicated by these active nests was late May through early June. There is probably only one reproductive period annually, but renesting might be attempted in the event of a failed first nest. Two nestlings about ten days old were in the nest found on June 10, 1971. A new fledgling was fed moths or spiders by both adults about every thirty seconds during the short time it was observed (less than half an hour). Other reproductive factors are unknown.

Incubation periods are unknown, although they probably last two to three weeks. The length of time to independence is also not known. Both the male and female defend the territory and guard the nest, the latter a critical task since the young are altricial. On July 22, 1971, a young Kauai 'o'o was seen, apparently independent of its parents, near the site where the nest had been found in May. The Kauai 'o'o is territorial. During the May-June nesting season, both sexes defend an area about 900 ft (274 m) across by aggressively chasing other birds out. They have been observed chasing conspecifics as well as apapane (Himatione sanguinea ), amakihi (Loxops viren ) and Kauai creeper (L. maculata ). Another behavior noted during the May-June nesting season was their frequently given "beep-beep" alarm call, which sounds like the roadrunner of cartoons. In these same two months they also started their melodious, flute-like duet calling a few minutes before 6:00 A.M. Audible at a distance of 0.25 mi (0.4 km), this dual fluting was given a dozen times until they settled down at about 10:30 A.M. From late morning they generally remained quiet, preened, and slept in lapalapa (Cheirodendron sp.) trees until after 3:00 P.M., when a few calls were heard. This period of tranquility would only be disturbed if the breeding pair had to become aggressive to chase away intruders, including any meddlesome Kauai 'o'o. Usually when clouds passed by they were quiet, but called when sunlight broke through. During non-breeding periods they were somewhat social and did not always chase away other birds feeding in the same area, or even in the same tree. The Kauai 'o'o is diurnal and nonmigratory. There is some limited movement out of the area they use during the nesting season, probably in response to insect and nectar abundance, but it is doubtful that it involves distances of more than 1 mi (1.6 km). The adults appear to spend most of their feeding efforts in late May and early June obtaining food for themselves and their young. The Kauai 'o'o consumes moths, spiders, insect larvae from within moss-covered trees, and millipedes. On one occasion a centipede was observed being taken to the nest. It searches 'ohi'a tree (Metrosideros collina ) trunks for insects to eat, including native cockroaches, the prognathogryllid crickets, and the smaller individuals of the genus Paratrigonidium, as well as some beetles. It feeds on the ubiquitous geometrid caterpillars as well as on some wood-eating species of caterpillars. It also retains, to a considerable extent, a fondness for the nectar of flowers, whether those of the 'ohi'a, the lapalapa, the Lobeliaceae, or the banana tree. The affection of the species for the lobelias is often revealed by the characteristic pollen sticking to its forehead.

Habitat

The Kauai 'o'o formerly used a wide variety of wet, mesic, and dry forest habitats in all or most of the Kauai forests. Possibly only one or two of the species survive in a remote, fairly pristine portion of the Alakai Swamp. It is also possible that its present range near Mt. Wai'ale'ale, the wettest spot in the world, never was the preferred and optimum habitat for this species, but represents an area as far removed as possible from decimating factors. The first known nest of the Kauai 'o'o was found deep in the Alakai Swamp in a dying 'ohi'a tree cavity about 11.8 in (30 cm) across on the inside. The nest was elliptical in shape and composed of rootlets of grasses, Adenophorus and other ferns, stems of the liverwort Herberta, small bits of mosses, a few small twigs of pukiawe (Styphelix tameiameiae ), and fine rootlets of 'ohi'a. The other two nests were found in similar settings. The openings in all three trees faced to the west, providing some protection from the prevailing northeast trade winds. 'Ohi'a, lapalapa, and dense native shrubs are the common vegetation.

Distribution

The past possible distribution of this bird on Kauai was throughout all forested areas on state and private land. There were fewer than 100 surviving birds in 1973, and a 1981 survey found only two birds in two stream systems in the Alakai Wilderness Preserve of the Alakai Swamp. There is a remote possibility that it occurs on Laau Ridge and Namolokama Mountain on private lands in the Alakai Swamp.

Threats

This species is threatened by low numbers, habitat degradation, and predation.

Conservation and Recovery

Now that the Kauai 'o'o population appears to be only two free-flying individuals, any proposed recovery measures are desperate at best. A first and critical step is to immediately locate additional specimens. Captive propagation of this bird and storage of the Kauai 'o'o live tissue or sperm have been suggested as the only actions that offer any promise of preventing its extinction. Compared with more specialized endangered birds, the Kauai 'o'o, with its eclectic feeding habits and preference for nesting in tree cavities, might respond favorably in captivity and reproduce. If this occurred, any captive-reared birds could be released into suitable habitat. The advantage of captive breeding over leaving the Kauai 'o'o in the wild would be to isolate the remaining individuals from disease and nest predation, two factors believed to have contributed to its decline.

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

Scott, J.M., et al. 1988. "Conservation of Hawaii's Vanishing Avifauna." Bioscience 38 (4): 238-253.

U.S. Fish and Wildlife Service. 1983. "Kauai Forest Birds Recovery Plan." U.S. Fish and Wildlife Service, Honolulu.