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cranes (Table 2 -3) . All of the documented roosts included surface water in <br />some form, either natural or artificially created and /or maintained. Though <br />the majority of these stopover roosts (35, or 54.7 percent) were in wetlands, <br />there appeared to be no consi stent rel ati onsh i p w ith regard to the size of the <br />wetl ands used; I. e. , whoopi ng cranes have roosted on wetl ands varying i n size <br />from less than an acre to several thousand acres (Johnson and Temple 1980, p. <br />42) . Of the 64 documented roosts, more occurred in artificial reservoirs <br />(approximately 22 percent) than in any other type, followed by Type 3 wetlands <br />(I4 percent) and shallow rivers (12.5 percent). Greater use of shallow <br />seasonal wetlands (Type 1 and Type 3) was noted i.n the spring; whereas <br />artificial reservoirs, Type 5 wetlands, and shallow rivers seemed to receive <br />more use in the fall when seasonal (intermittent) wetlands are less abundant. <br />Johnson and Temple (1980, p. 37) mentioned three reports of whooping cranes <br />possibly using upland habitats for roosting, but they were unable to <br />substantiate them. <br />In addition to the presence of shallow water, the prerequisites of stopover <br />roosts used by migrating whooping cranes appear to be good horizontal and <br />overhead visibility, cl ose proximity to feeding sites and reasonable isolation <br />f ran human developments and /or disturbances. Their habit of roosting in water, <br />as well as their preference for roosts which offer good visibility in all <br />directions, apparently provides protection against the approach of predators. <br />Moreover, Johnson and Temple (1980, p. 50) stated that there is some evidence <br />to support the conclusion that the availability of relatively fresh drinking <br />water is a factor which influences the cranes' choice of roosts. <br />Major features of standing- and flowing-water roost sites used by migrant <br />whooping cranes are presented in Table 2 -4. The habitat characteristics listed <br />in this table are based on an evaluation of documented roost sites by Johnson <br />and Temple (1980, pp. 39-43) and Johnson (1981, p. 40). In compil ing this <br />information, Johnson and Temple assessed 57 roost sites in standing water <br />versus only 7 in flowing water. Johnson's paper, published a year later, <br />summarized the characteristics of 10 documented riveri ne roosts [6 in Nebraska, <br />4 of which were on the PI atte River (NSPC 1985, p. 13) 1. Johnson and Temple <br />(1980; pp. 43 -44) stated that if a wetl and possessed the features listed, "it <br />has the potenti al for bei ng used as a roost by whoopi ng cranes. " They <br />expressed the qualification that some of the listed characteristics may prove <br />in the future to be unimportant to whooping cranes, whereas other <br />characteristics not listed may be of great importance. <br />Interestingly, Johnson and Temple (1980, p. 44) reported several instances of <br />whooping cranes using "lower quality" roost habitat in areas where "higher <br />qual ity" habitat was readily available and within the field of vision of the <br />flying birds (i.e. , at a common flying altitude of approximately 1,000 feet, <br />whooping cranes can probably visually survey an area of at least 36 square <br />miles [Johnson and Temple 1980, p. 721) . On three occasions whooping cranes <br />were noted to have roosted on stockponds within 30 miles of the Platte River <br />rather than using the river itself. In one case, two birds spent at least 4 <br />days within 12 miles of the river; they roosted on a small stockpond and <br />foraged in a brave -grass pasture where the only potential food items were grass <br />seeds and possibly grasshoppers. Johnson and Temple (p. 44) commented as <br />fol l owe: <br />2 -13 <br />