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LAKI,t JANLAI ILL I tCAfVtJ wIlV ; I r and censusin inapt cereal rain crop (California Dep. Water ! expended less etTort searching for g g II cranes at Pixley NWR, Merced NWR, Modesto Res., unpubl.) hosts only 1,500-2,000 Lesser and other locations in the San Joaquin Valley Sandhill Cranes (T. Pogson, unpubl. data), and than on the S-SJ Delta and the Sacramento Val- overall use of that geographic area by large cranes icy. Littlefield and Thompson (1979) found few was lower than use of the Thornton region(Table Greater Sandhill Cranes in the San Joaquin Val- 1). The Cosumnes River is not dammed and its ley, and our censuses of Lesser Sandhill Cranes floodplain is subject to annual flooding from win- there in 1981, 1982,and 1983 revealed few large ter rainfall and snowmelt in late winter. This cranes (T. Pogson, unpubl. data). The reduced region provided wetland habitats for large num- effort in the southern Central Valley probably bers of cranes in both winters after waterfowl caused underestimation of the number of cranes hunting clubs were drained in the Thornton re- in these little-used portions of the winter range gion. and a slight underestimation of the population's The same sites used by the population in the size. late 1960s and mid-1970s (Littlefield and It is possible that we sometimes misidentified Thompson 1979), the Llano Seco Rancho south- Lesser Sandhill Cranes as"large cranes"(Greater west of Chico, Gray Lodge WMA in the Butte and Canadian Sandhill Cranes)while conducting Sink, the El Dorado Gun Club at Thornton, and roost counts at sites where large cranes and Less- the Faith and Mape's Ranches west of Modesto, Ii er Sandhill Cranes were both present in large were still important in 1983-1984 and 1984— numbers. This misidentification would have in- 1985. The numbers of large cranes using these I� flated our regional estimates of the number of sites in the late 1960s and mid-1970s were sim- large cranes. However, it is equally likely that we filar to the numbers of cranes using these sites at incorrectl.,classified large cranes as Lesser Sand- a comparable time of year during the winter of ! hill Cranes. Although the magnitude of this error 1983-1984. is unknown, we do not believe it significantly During the winters of 1983-1984 and 1984— t�C affected our estimates. 1985, 98% of the population's winter range was It privately owned.Only 19 km'of the winter range G DISTRIBUTION AND IMPORTANT (ca. 2%), which included important roosting sites, WINTERING SITES was managed by state and federal wildlife man- During our surveys,large numbers of cranes were agement agencies as waterfowl hunting areas.The present in the same regions that were heavily majority of the population used private lands for } used ly the population in the late 1960s and mid- feeding and roosting. Use of public lands by cranes ; 1970s (Littlefield and Thompson 1979). The peaked in October 1983 when 36% of the pop- Chico, Butte Sink, Thornton, and Modesto ulation roosted at two sites in the Butte Sink, the regions were the most important winter areas for Bean Patch, and Gray Lodge Wildlife Area (Ta- f the population in 1983-1984 and 1984-1985, as ble 1). iC in 1969-1971 and 1976. We, however, detected iX the movement of 50-60%of the total population SIGHTINGS OF MARKED CRANES from the Butte Sink to Chico and Thornton dur- The movement of marked cranes among regions ing November and December (Table 1), which demonstrated relationships among different por- was not detected by Littlefield and Thompson tions of the winter range. From November :f €{ (1979). Residents of the Chico, Butte Sink, and through January marked cranes departed from Thornton regions reposed that this movement the Butte Sink and moved north within the Sac- is an annual event (M. Meyers, J. Buress, M. ramento Valley to Afton and Chico, or south out Leighty, and L. Pucci, pers. comm.). of the Sacramento Valley to Thornton on the The Thornton area supported the greatest S-SJ Delta. In January and February marked ft ? number of large cranes among regions in the Cen- cranes left Thornton and moved to the nearby tral Valley. Use of the Thornton area by 5,000— floodplain of the Cosumnes River. Cranes which 6,000 Lesser Sandhill Cranes(T. Pogson,unpubl. were banded at Malheur NWR, in southeastern E� data),in addition the the 1,772-3,829 large cranes Oregon, were disproportionately concentrated in It (Table 1), was probably related to the availability the Thornton region, while cranes banded at Sy- of waste corn, the dominant crop in this region. can Marsh, in southcentral Oregon, were dispro- The Sacramento Valley, where rice is the dom- portionately concentrated in the Butte Sink (T. VI-135 ,!c�lsiy E��1u.