Laysan Duck

Anas laysanensis

Description

The Laysan duck, Anas laysanensis, which has also been known as the Laysan teal, is a dark, reddish brown duck, 16 in (40.6 cm) long, resembling a female mallard. Its dark plumage is accented by bright purple-green patches bordered with white on the forewing. First-year birds have white eye-rings; older birds develop a more extensive irregular patch of white that extends toward the back of the head. Feet and legs are bright orange in males, duller in females. Bill color is the easiest way to distinguish the sexes. Males have a blue-green bill with black spots along the top of the upper beak; females have a dull, brownish yellow bill with black spots along the lateral borders of the upper mandible.

Behavior

The Laysan duck is primarily insectivorous, feeding on brine flies, cutworm larvae, miller moths, and small crustaceans. Birds nest from February through August, although most eggs are laid between May and late July. Clutch size is three or more eggs.

Habitat

Laysan ducks are usually found in the lagoons, tidal pools, and marshes of the island. During hot, clear weather, the birds seek cover by mid-morning in dense stands of Pluchera, Ipomoea, and Sicyos, remaining there until the temperature cools in the early evening.

Distribution

The species was first reported in 1828 on both Laysan and Lisianski Islands. Since then it has been seen only on Laysan Island and has always been rare. The Laysan duck came close to extinction in the early part of the twentieth century. Between 1910 and 1920 the population hit a low of about 20 birds. By 1990, the population was holding stable at about 500. Several hundred Laysan ducks are held in breeding facilities throughout the world.

Threats

In 1890 rabbits were introduced to the island and rapidly destroyed the island's vegetation. Loss of ground cover laid bare the topsoil, which was subsequently eroded by wind and rain. This ecological disaster resulted in extirpation of the Laysan miller-bird, the Laysan rail, and the Laysan honeycreeper. The Laysan duck and the Laysan finch (Endangered) barely survived. When the rabbits were eliminated in 1923, plant life on the island began to recover. Present conditions are thought to approximate those prior to the introduction of rabbits.

Conservation and Recovery

During the late 1950s a captive propagation program was developed as a backup against natural or human-caused disasters. Ducks were taken from Laysan Island and sent to the Honolulu Zoo for acclimatization before being shipped to various zoos and game bird breeders around the world. Breeding stock was sent to the New York Zoological Park, the San Diego Zoo, the Wildfowl Trust in England, the San Antonio Zoological Gardens, and Tracey Aviary. Many zoos and breeding farms now raise Laysan ducks in captivity, and a bird exchange program is encouraged to prevent close inbreeding.

Because of its limited distribution on Laysan Island, the Laysan duck will always be considered a vulnerable species. Laysan Island is managed as part of the Hawaiian Islands National Wildlife Refuge and has been designated as a Research Natural Area under the International Biological Program. The island is being considered for inclusion in the National Wilderness Preservation System. Presently, only scientists are permitted access to the island.

Contact

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

References

Berger, A. J. 1981. Hawaiian Birdlife. University of Hawaii Press, Honolulu.

Moulton, D. W., and M. W. Weller. 1984. "Biology and Conservation of the Laysan Duck (Anas laysanensis )." Condor 86:105-117.

U.S. Fish and Wildlife Service. 1982. "Laysan Duck Recovery Plan." U.S. Fish and Wildlife Service, Portland. 49:229-238.