Yuma Clapper Rail

Rallus longirostris yumanensis

Description

The Yuma clapper rail is one of seven North American subspecies of the clapper rail, which is a large, long-billed, henlike marsh bird. The Yuma subspecies, which averages 14-16.5 in (36-42 cm) in length, is gray-brown with a tawny breast, a white throat and undertail, and bars across the flanks.

Behavior

The Yuma rail feeds on crayfish, small fish, clams, isopods, and a variety of insects. Most of the U. S. population remains on its breeding grounds from mid-April to mid-September. The rails then migrate south to Mexico for the winter. Little is known of Yuma clapper rail breeding and nesting. Clutch size is thought to be about six eggs. Nests are constructed on dry hummocks or in small shrubs amid dense cattails just above water level. Two types of nests have been found: one of sticks and dead leaves, another of finer stems with dry blossoms still intact.

Habitat

In the United States, Yuma clapper rails nest in freshwater marshes. They prefer mature stands of cattails and bulrushes along the margins of shallow ponds with stable water levels. Mexican populations prefer brackish marshes, dominated by dense stands of tall salt cedar (Tamarix gallica ) with an understory of iodine bush (Allenrolfia occidentalis ).

Distribution

In general, western clapper rails range from northern California along the Pacific coast to central Mexico. The Yuma clapper rail has been sighted along the Colorado River where Nevada, Arizona, and California meet, south to Yuma, Arizona, and into Mexico. The bird probably winters in Mexico. It is thought that the Yuma clapper rail was not distributed along the Colorado River until suitable habitat was created through dam construction.

A survey conducted in 1969 and 1970 estimated about 700 breeding birds in the United States. Since then, an annual spring calling count survey has been conducted during the rail's nesting and breeding season. In 1990, the U. S. Fish and Wildlife Service, the U. S. Bureau of Land Management, the U. S. Bureau of Reclamation, the Arizona Game and Fish Department, the California Department of Fish and Game, and local National Audubon Society chapters participated in the calling count survey along the Colorado River and in the other isolated areas where the rail is known to occur. The number of responses to taped calls was approximately twice the figure for the three previous years (673 compared to 272-350 in 1987-89). The encouraging survey results led researchers to conclude that the population was possibly increasing due to stabilizing habitat conditions. The increase also is attributed to additional areas being surveyed and more time being invested in the survey. The habitat area is defined by the Colorado River delta (Mexico), the Salton Sea (California), Topock Marsh (Arizona), and along the Gila River to near Tacna (Arizona).

Threats

Water control projects on the Colorado have changed the nature of this once free-flowing river. Dams eliminated many backwaters and created new marshes and wetlands. Regulated water releases in the lower Colorado River slowed currents enough to allow sedimentation, which in turn allowed cattail and bulrush marshes to emerge. As new habitat developed upstream, the rails moved in. The Salton Sea, California's largest inland lake, was created in 1905 when the Colorado River overflowed its banks into Imperial Valley. Protection and development of these wetlands for waterfowl management created habitat for the Yuma clapper rail. Other suitable rail habitat, however, has been lost through dredging and channelization projects along the Colorado River, and the Salton Sea has become a wasteland itself, a site of major concern for environmentalists working to bring it back from the devastation of sewage drainage and a disappearing water table.

Conservation and Recovery

Although the rail population appears to be stable, its fate is tied to the various water projects along the Colorado River. The key to maintaining or expanding the rail population is maintaining early growth stages of cattail marsh by creating shallow water areas. Eventually, a mat of dead cattails forms in the shallows, providing nesting cover for rails.

Contacts

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

U. S. Fish and Wildlife Service
Regional Office, Division of Endangered Species
P.O. Box 1306
Albuquerque, New Mexico 87103-1306
Telephone: (505) 248-6911
Fax: (505) 248-6915
http://southwest.fws.gov/

References

Banks, R. C., and R. E. Tomlinson. 1974. "Taxonomic Status of Certain Clapper Rails of Southwestern United States and Northwestern Mexico." Wilson Bulletin 86 (4): 325-335.

Moffitt, J. 1941. "Notes on the Food of the California Clapper Rail." Condor 43: 270-273.

Ripley, S. 1977. Rails of the World: A Monograph of the Family Rallidae. D. R. Godine Publishing, Boston.

U. S. Fish and Wildlife Service. 1984. "Yuma Clapper Rail Recovery Plan." U. S. Fish and Wildlife Service, Albuquerque.