Communal Roosting and Foraging Behavior of Staging Sandhill Cranes

摘要: ABsTRAcr.-Each spring more than 300,000 Sandhill Cranes (Grus canadensis) roost communally at night in river channels the Platte River Valley of Nebraska and disperse dawn to forage agricultural fields. with central roosts had activity ranges double size those peripheral roosts; 42% birds changed prior onset migration. Minimum daily flight distance generally increased during staging period. used native grassland planted hayland often expected, relative their percentage occurrence, fed longest there; cornfields were under-utilized. These differences probably reflect, part, (1) limited distribution grasslands haylands resulting a greater energy expenditure acquire protein form macroinvertebrates (2) wider adequate energy-rich foods but protein. efficiently conserve by following conspecifics from communal local feeding grounds, settling fields where foraging flocks are already present, establishing diurnal centers. Alert behavior varied flock not as predicted group size, presumably because predation adult cranes is inconsequential. Received 4 Jan. 1993, accepted 15 June 1993. midcontinent population nutrient reserves for migration reproduction while on areas along