Roosting Behavior and Habitat of Migrant Greater Sandhill Cranes

Abstract

The eastern population of greater sandhill cranes (Grus canadensis tabida) has increased rapidly in recent years. Drainage of wetland habitats and crane intolerance of disturbance from waterfowl hunting have forced the expanding population into reduced areas during migration. At the primary staging site, the Jasper-Pulaski Fish and Wildlife Area (JPFWA) in northwestern Indiana, as many as 13,000 cranes, apparently most of the entire population, may roost in as little as 18 ha of suitable undisturbed areas. Primary roosting requirements at JPFWA were water generally <20 cm deep and lack of human disturbance. Cranes preferred to land in shallow water or on bare or sparsely vegetated mud flats. As long as shallow water was available, cranes at JPFWA did not avoid roosts where woody vegetation had encroached upon shorelines. Cranes required lesser distances from human activity when roosts were surrounded by trees than when roosts were open and visible from roads. Waterfowl hunting from 1000 until 1400 hours every 3rd day in 1978 did not alter patterns of roost use. Hunting from one-half hour before sunrise until noon or sunset every other day in 1979 caused cranes to avoid roosts. Lack of crane use of areas other than JPFWA probably results from unfavorable location in the migration path and absence of tradition based on historical habitat availability. J. WILDL. MANAGE. 45(4):842-857 The eastern population of greater sandhill cranes was drastically reduced during human settlement to a few dozen nesting pairs in Michigan and Wisconsin (Henika 1936, Walkinshaw 1949:134). Between 1870 and 1915, the period of greatest decline (Walkinshaw 1949:130), about 170,000 ha of nesting and probable staging habitat along the Kankakee River in northwestern Indiana was completely drained (Meyer 1935). The Jasper-Pulaski Fish and Wildlife Area was established 5 km south of the river in the early 1930's. Increasing numbers of cranes sighted at JPFWA during migration roughly paralleled recovery of the population, which now nests in Michigan, Wisconsin, Minnesota, Ontario, and Manitoba (Lewis 1977). From occasional stragglers in the 1930's, peak concentrations of fall migrants at JPFWA increased to several hundred during the 1940's and 1950's, 2,700 in 1968 (Shroufe 1976), and 13,000 in 1978. Spring counts have increased from a few hundred to around 6,000 cranes. Concentrations of less than 1,000 cranes occur early in fall migration at areas in Wisconsin and Michigan. However, most of the population appears to be at JPFWA simultaneously in mid-tolate fall, when as many as 13,000 cranes may roost in as little as 18 ha of suitable habitat in shallow waterfowl impound-