Colinus virginianus ridgwayi
|Listed||March 11, 1967|
|Family||Phasianidae (Pheasants and Quail)|
|Description||Mottled, reddish-brown quail with a cinnamon breast and black head.|
|Habitat||Semiarid and desert grasslands, desert scrub.|
|Food||Seeds, plants, insects.|
|Reproduction||Clutch of five to 15 eggs.|
|Threats||Livestock grazing, fire suppression, predators.|
|Range||Arizona; Mexico (Sonora)|
The masked bobwhite, Colinus virginianus ridgwayi, is a quail with a short tail and plump body, ranging from 8.5-10.5 in (22-27 cm) in length. Males are characterized by a cinnamon breast, black head and throat, and a varying amount of white above the eye. Females lack the black head and cinnamon breast, but instead are a mottled brown above, with a buff head and white breast. Females are essentially indistinguishable from the Texas bobwhite (C. v. texanum ), which is found in subtropical Texas and Tamaulipas, Mexico.
The bobwhite is a seasonally gregarious bird, gathering into social groups called "coveys." Broods of five to 15 young form the nucleus of the cool weather covey. Unproductive adults and young separated from other broods may join, but covey size rarely exceeds 20 birds. Masked bobwhites usually remain in coveys until late June, when mating bonds form, and pairs gradually separate from the covey to nest. Breeding season, heralded by the "Bob-whoit!" call of the male, begins with July rains. Birds build their nests on the ground and require thick cover for concealment; therefore, nesting may be delayed until sufficient ground cover has developed. If rains are delayed or absent, masked bobwhites may not nest that season. Chicks begin to hatch in late July and may continue to hatch until early November.
The masked bobwhite feeds on a variety of legume and weed seeds during the fall, winter, and early spring; and plant material and insects in summer and early fall.
Masked bobwhite habitat extends through open grasslands, across semiarid desert scrub, and into desert grasslands at the extreme northern edge of its range. Grass and weed cover is seasonal; trees and bushes vary in composition and density from site to site. In the southern and eastern portions of the Sonora savannah grassland, an enormous variety of thorny scrubs and trees are present. At the northern limits, mesquite is present throughout. Habitat elevation rises 500-4,000 ft (150-1,200 m) above sea level. Freezing temperatures are infrequent, and almost never last more than 24 hours. July through September rainfall averages 10 in (25 cm).
The masked bobwhite has always been restricted to the level plains and river valleys of Sonora, Mexico, and extreme south-central Arizona. The eastern and southern distribution of the masked bobwhite is limited by the merging of Sonoran savannah grassland with the more dense Sinaloan thorn-scrub. To the west and northwest a decrease in summer precipitation excludes bobwhites from the desert scrub communities of the Central Gulf Coast, Lower Colorado River, and Arizona Upland subdivisions of the Sonora Desert. The northern limit of historic masked bobwhite range is defined by the Altar and Santa Cruz Valleys of Arizona.
By the beginning of the twentieth century the masked bobwhite was eliminated from southern Arizona when native grasslands were depleted by cattle grazing. As cattle ranching spread throughout Sonora after 1930, the masked bobwhite began to disappear from there also. As of 1995, the species was known in three populations totaling less than 1,000 individuals, existing in Sonora, Mexico. One population, with an estimated 300-500 birds, existed in the United States in south-central Arizona on the Buenos Aires National Wildlife Refuge.
Grazing cattle and other livestock remove grasses and forbs from the land, depriving the masked bobwhite of nesting habitat, cover, and food. Depletion of ground cover prevents brushfires, allowing woody plants to invade and gradually take over the grasslands, forcing out the masked bobwhite. The woody habitats are then occupied by bobwhite relatives—the scaled quail, Gambel's quail, or the elegant quail.
Conservation and Recovery
From 1937 through 1950, unsuccessful attempts were made to reintroduce the masked bobwhite to Arizona and New Mexico and to restore populations in Sonora. Pen-raised captive birds or wild Mexican bobwhites were released in unsuitable habitats, outside of their historic range, and did not survive.
A recovery program for the masked bobwhite began in 1966, when a successful captive breeding program was established at the Patuxent Wildlife Research Center (now the Patuxent Environmental Science Center, a facility of the National Biological Service, or NBS). Within two decades, this captive colony was producing 3,000 chicks each year under carefully supervised conditions. Through the 1970s, biologists, trying to pinpoint suitable habitat, released these pen-raised birds to the wild at different locations in Arizona; most birds disappeared within two months, due to coyote predation. Efforts gradually narrowed to the Altar Valley's privately owned Buenos Aires Ranch, which seemed to provide ideal masked bobwhite habitat. In 1985, the Buenos Aires Ranch was acquired by the U. S. Fish and Wildlife Service (FWS) and became the Buenos Aires National Wildlife Refuge (BANWR) in southern Arizona. Because captive propagation of the masked bobwhite is no longer considered a research task, the NBS has withdrawn from the program. In the spring of 1996, 657 masked bobwhites were shipped to a new propagation facility at BANWR. The FWS has assumed the task of rearing masked bobwhites at this facility for release on the refuge.
Current reintroduction techniques have become more sophisticated. Refuge-raised chicks are returned to the wild in family groups under the tutelage of "foster parents," usually wild male Texas bobwhites that have been sterilized. These foster parents teach the released birds essential survival skills. Although the long-term success of these efforts depends as much on weather cycles as on chick survival rates, biologists feel that they are on the right track with the masked bobwhite.
The goal, as set forth in the recovery plan, is to establish a self-sustaining population in Arizona within 10 years, thus reversing a trend that drove the masked bobwhite out of this country more than 80 years ago.
A 1995 revision of the recovery plan noted that the species recovery (delisting) criteria now includes the establishment of two viable populations in the United States; the cooperation with the Mexican government in reintroducing two or more populations in Mexico; and the maintenance and increase of the existing Mexican populations. Among the actions needed to achieve these goals are the maintenance of at least two captive populations at widely separated locations; the continued release of propagated stock on BANWR until a viable, self-sustaining population of 500 birds is established; and the implementation of habitat management on BANWR to maintain and increase the existing populations.
Other actions called for included determining: species biology, population dynamics, habitat needs, and management and winter requirements in the United States and Mexico; as well as assisting in the monitoring of masked bobwhite populations in Mexico.
Banks, R. C. 1975. "Plumage Variation in the Masked Bobwhite." Condor 77: 486-487.
Johnsgard, P. A. 1973. Grouse and Quails of North America. University of Nebraska Press, Lincoln.
Phillips, A., J. Marshall, and G. Monson. 1964. The Birds of Arizona. University of Arizona Press, Tucson.
U. S. Fish and Wildlife Service. 1984. "Revised Masked Bobwhite Recovery Plan." U. S. Fish and Wildlife Service, Albuquerque.
U. S. Fish and Wildlife Service. 1995. "Revised Masked Bobwhite Recovery Plan." U. S. Fish and Wildlife Service, Albuquerque.