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<br />';/... <br /> <br />8 <br /> <br />of WBNP. These birds winter along the Gulf of Mexico coast at Aransas NWR and adjacent <br />areas (Fig. 2). The winter habitat extends 48-56 km along the coast from San Jose Island <br />and Lamar Peninsula on the south to Welder Point and the central portion of Matagorda <br />Island on the north, and consists of estuarine marshes, shallow bays, and tidal flats (Allen <br />1952, Blankinship 1976) (Fig, 3), Some individuals also occur occasionally on nearby <br />rangelands or farmlands, Forty-five AWP pairs nested in 1993. The December 1993 <br />population was 141 birds. <br /> <br />Another wild flock consists of eight individuals reared by wild sandhill cranes (termed cross- <br />fostered because they were reared by another species) in an effort to establish a migratory, <br />Rocky Mountains Population (RMP) and one captive-reared bird released in a recent <br />experiment. The project began in 1975 with the transfer of wild whooping crane eggs from <br />nests in WBNP to the nests of greater sandhill cral1es l.G.. Q. tabidal at Grays Lake NWR in <br />southeastern Idaho. The sandhill cranes became tbe foster parents to the whooping crane <br />chicks and taught them the migration route which ~he parents traditionally followed. The <br />RMP birds spend the summer in Idaho, western Wyoming, and southwestern Montana and <br />winter in the middle Rio Grande Valley of New Mexico. <br /> <br />The third wild population consists of ten birds remaining from 19 captive-reared whooping <br />cranes released in the Kissimmee Prairie of Florida !n February and December of 1993, This <br />flock has been designated experimental nonessenti~1 and is the first step in an effort to <br />establish a nonmigratory population in Florida, This population is hereafter called the Florida <br />population (FP). <br /> <br />In May 1993, whooping cranes were located at five captive sites. Two captive flocks are <br />maintained by the U,S. Fish and Wildlife Service, one at Patuxent Wildlife Research Center <br />(PWRC) containing 55 birds and one at International Crane Foundation lICF) containing 26 <br />birds in December 1993. The Canadian Wildlife Service is starting a population at the <br />Calgary Zoo which now contains 1 6 birds. Three birds reside at San Antonio Zoological <br />Gardens and a single bird is in captivity at the Rio (,2rande Zoological Park in Albuquerque, <br />New Mexico, being treated for avian tuberculosis, <br /> <br />In the 1970's and early 1980's, the AWP was increasing at an annual rate of 4 percent, <br />double the rate observed prior to the mid 1950's (Binkley and Miller 1983), Subsequent <br />population studies indicate a 10-year cycle of unknown cause in survivorship (Boyce and <br />Miller 1985, Boyce 1987, Nedelman lit Ai, 1987), <br /> <br />C. Habitat <br /> <br />The current nesting area within WBNP lies betweer) the headwaters of the Nyarling, Sass, <br />Klewi, and Little Buffalo rivers. The area is poorly drained and interspersed with numerous <br />potholes. Wetlands vary considerably in size, shape and depth, and most possess soft marl <br />bottoms, Wetlands are separated by narrow ridges which support an overstory of white <br />spruce (~ olauca), black spruce If. mariana), tamarack ~ laricinal, and willows (~ <br />ll!m.), and an understory of dwarf birch IBetula alar:)dulosa), Labrador tea ILedum <br />aroenlandicuml, and bearberry (ArctostaDhvlos uva~ursi), Bulrush IScirous validus) is the <br />dominant emergent in the potholes used for nesting, although cattail (TvDha m,), sedge <br />