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26 <br />Wintering Grounds M nagement: Management of Aransas NWR is a sizeable and complex <br />operation (Johnson 1976). Prime habitat is limited and natural foods may at times be in <br />short supply. Two 40 -ha fenced enclosures were developed during 1964 -1968, in which <br />various cereal and root crops were grown. Some whooping crane use of these fields <br />occurred but most food crops intended for whoopers were consumed by the more numerous <br />sandhill cranes and Canada geese (Brants.9 anadensis) (Shields and Benham 1969). Another <br />innovation was the diking of a 28 -ha impoundment equipped with a high volume, low -lift <br />Pump designed to bring large quantities of saline water and marine life into the basin; the <br />exit of live food items was prevented by screens at spillway outlets. Limited use by <br />whooping cranes was achieved during one winter when they were attracted to the site by <br />"bait" grains, but in subsequent years whooping cranes did not use the artificial <br />impoundment. <br />During the mid- 1960's; whooping cranes were attracted by grains spread for their use. <br />Such "baiting" has since been avoided because concentrating the birds increases the <br />potential for a disease outbreak or the spread of parasites. However, baiting could be <br />attempted to attract whoopers from the tidal areas in certain emergency situations, such as <br />during oil or chemical spills, or periods of food scarcity. <br />Prescribed burning is used to reduce height and density of grasses, remove brush, and to <br />modify plant composition on uplands to make them more attractive to whooping cranes. <br />This management was attempted in the past by mechanical cutting and grazing by livestock. <br />Burned areas are almost immediately utilized by whoopers (Hunt 1987). Currently, 10 <br />prescribed burn units averaging 564 ha are located in the crane area at Aransas NWR. <br />Depending on the acorn crop, the units are burned on a 3 -year rotation. Additional burning <br />is done on Matagorda Island, as well as on private lands on San Jose Island and Welder <br />Flats. <br />The most complete counts of the AWP are made during winter. Aerial censuses are made <br />weekly from the time the first whooping cranes appear, less frequently in mid - winter, and <br />again weekly until the last cranes depart. Flights provide information on mortality, habitat <br />use, pair formation, territory establishment, and population age structure by identifying all <br />color- banded birds present. These flights, and an irregular schedule of boat patrols, serve to <br />alert the refuge staff to hazards or harassment of cranes resulting from human activity, <br />including accidental spills along the GIWW. If a crane is determined to be "missing," then a <br />ground search is initiated to locate the carcass. Additional protection of some wintering <br />habitat outside Aransas NWR has been provided by National Audubon Society's leasing <br />Ayres and Roddy islands, the Dunham Island area, and portions of Rattlesnake and <br />Matagorda islands from the State of Texas. The leasing arrangement substantially reduces <br />the potential for disturbing or harassing cranes wintering in these areas. <br />Whooping cranes use marshes bordering Matagorda Island. In 1942, the Federal <br />government purchased approximately 7,700 he of the Island, and leased 2,400 ha from the <br />State of Texas, to establish an airbase and bombing range. This area was declared excess <br />Property in 1975. Administration of the property was transferred to the Service as part of <br />the National Wildlife Refuge System in 1978. In 1988, the Service completed purchase of <br />2,232 ha on the south end of Matagorda Island. A new agreement between Service and the <br />