Molokai Thrush

Myadestes lanaiensis rutha

Description

The Molokai thrush, Myadestes lanaiensis rutha, is a fairly large, heavy-bodied bird, about 7-8 in (18-20 cm) long. Adults are dark brown above and gray below; immatures are spotted below. The Hawaiian name for this thrush is olomao, and it is also commonly known as the Lanai thrush. This species was originally classified as Phaeornis obscurus rutha.

Behavior

The Molokai thrush is a reclusive bird that usually keeps beneath the forest canopy. It feeds on fruits, berries, and insects. Its breeding biology is unknown, but a closely related bird on the island of Hawaii, the omao (Phaeornis obscurus obscurus ), constructs a bulky nest of branches, fern fronds, mosses, and leaves. Clutch size is one or two eggs.

Habitat

The forested plateau within the two major northern valleys, Pelekunu and Wailau, is the most isolated and pristine land in the main Hawaiian Islands. The Molokai thrush is found in a wet, montane ohia forest with a dense understory of mosses, vines, and tree ferns at elevations above 4,000 ft (1,219.2 m).

Distribution

This species was once very common throughout Molokai and was regularly collected by scientists in the 19th century. During the 20th century the species declined rapidly, and, until surveys on Molokai in 1979 and 1980, there were only two reported sightings. At present, the Molokai thrush is restricted to the Olokui Plateau between Kamakou Peak and Pepeopae Bog. The population was estimated at 19 birds in 1986.

Threats

European settlement of Molokai eliminated all dry forests on the south coast up to at least 3,000 ft (914.4 m), converting most of the land to pasture. By the turn of the twentieth century, only the very wet, mountainous ohia forest remained, and many native Hawaiian birds had vanished. Although deforestation has stopped, habitat destruction continues. Browsing and rooting by feral goats and pigs and axis deer have disrupted the growth of native vegetation, allowing non-native plants, including strawberry guava, blackberry, New Zealand flax, and various gingers, to invade. The original ground cover has drastically changed in composition, distribution, and density. Many native forest birds have been unable to adapt to these conditions, and populations have declined. Avian pox and malaria, spread by introduced mosquitoes, have played a large role in the decline of many native Hawaiian birds. Most remaining birds live at higher elevations where the mosquito density is low. Scientists are now concerned that a temperate-zone subspecies of the night mosquito (Culex pipiens pipiens ) may become established at higher elevations and further spread avian diseases.

Conservation and Recovery

The first effort to conserve native birds was made in 1903 when the State Forest Reserve system was created. The protection of watershed was the primary concern, and reserve management included fencing out cattle, hunting of feral animals, and the reforestation of denuded areas with exotic trees. The State Reserve system holds and actively manages about 30% of the remaining forest resources on the island.

Contact

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. 1984. "The Maui-Molokai Forest Birds Recovery Plan." U.S. Fish and Wildlife Service, Portland, Oregon.

Van Riper, C. III, and J.M. Scott. 1979. "Observations on Distribution, Diet, and Breeding of the Hawaiian Thrush." Condor 81: 65-71.