Feeding Ecology of Sandhill Cranes during Spring Migration in Nebraska

We studied the food habits of midcontinent sandhill cranes (Grus canadensis) during spring 1978 and 1979 at their primary staging area along the Platte River and compared population food and foraging habitat requirements with availability. Crane diets varied among the 3 principal foraging habitats, but not between sexes, ages, or years. Cranes feeding in cornfields ate >99% corn (total dry wt); those feeding in native grasslands and alfalfa fields consumed 79-99% invertebrates. The composite diet of cranes was 97% corn and 3% invertebrates, including 2% earthworms, 0.5% snails, and 0.5% insects. Presumably, corn provided energy, whereas invertebrates from grasslands and alfalfa fields provided supplemental nutrients to compensate for protein and calcium deficiencies in corn. The mean density of waste corn decreased (P 50%. Management by burning, haying, and grazing is compatible with crane use of grasslands, and reduced-till farming could benefit cranes by increasing invertebrate populations. J. WILDL. MANAGE. 50(1):71-79 A growing awareness of the impact of water resource development on spring staging habitat of sandhill cranes in the Platte River Valley of Nebraska has stimulated private, state, and federal conservation efforts (Krapu et al. 1982). Depletion of flows in the river has increased development of native wet meadows for crop production and reduced the width of river channels. This has concentrated cranes in restricted reaches of the river and caused concern that food resources needed to meet energy and nutrient requirements of the population may become inadequate. In particular, the role of grasslands in the feeding ecology of cranes needs more study (Wheeler and Lewis 1972, Reinecke and Krapu 1979). Our research was part of a larger investigation of sandhill crane staging ecology (U.S. Fish and Wildl. Serv. 1981) that provided necessary background information to assess the management implications of population food and energy requirements. The objectives of our study were to: (1) relate qualitative aspects of food use t foraging habitat, (2) calculate daily and seasonal population food requirements, and (3) estimate food availability for comparison with projected requirements. We thank C. R. Frith and R. J. Wicht for assistance in contacting landowners and the landowners of the Platte River Valley for access to their properties. D. Janke and D. Jenson contributed to our corn sampling project. B. A. Hanson assisted with insect taxonomy and, along with D. G. Jorde, R. E. Atkins, and G. R. Lingle, collected crane specimens. Molluscs and earthworms were identified by F. M. Uhler and W. N. Beyer, respectively. D. H. Johnson and A. M. Frank supervised the statistical analyses, and T. J. Dwyer and C. E. Korschgen reviewed the manuscript.