Migration Dynamics of the Whooping Crane

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'It would seem to us that the [Platte] river provided much higher 'quality' roosting habitat than the stockpond, and that its associated wet meadows and agricultural fields probably offered being mnervouspotential or of being under anycadditional ed no signs stress where they were." Such quandary over the use of "lower quality" versus "higher quality" habitat of course impl ies that whooping cranes view their options with the very perspective and bias. Presented with a clear choice, however, sel ecti on of one potential roost site over another would seem to indicate that, as far as the cranes are concerned, the selected option is the most favorable in meeting their overall stopover requirements. In other words, what is 11 ower quality" to humans, may be "higher quality" to whooping cranes. It is important to understand, too, that listings of confirmed sightings represent nonsystematic data which are biased by the distribution of qualified observers. As Johnson and Temple (1980, p. 65) pointed out, there is a much s at greater probabi l ity of detecti ng and reporti ng w hoopsii nagecr and pro poverty it dl if e certain locations al ong the flyway (e. g. , federal, refuges and preserves) where trained biologists and /or other experienced observers are stationed in the field most of the time during the migration seasons. On the other hand, the likelihood of detecting whooping crane stopovers at i sol ated f a ponds, sukhabidtatsn other l mayactual actually bee would be frequent. much less, even though the such Similarly, sighting efforts along the central Platte River have been enhanced by intense censusi ng of sandhill cranes in this area since 1959 (the sandhil l crane's spri ng stagi ng peri od overl aps much of the whoopi ng crane I s sons and migration period through Nebraska) . In spite of this, however, Temple (1980, p. 21) reported that fran 1960 -1979 there were only three confirmed sightings of whooping cranes on the Platte River, as compared atto least 14 confirmed sightings on wetlands within 30 miles of the Platte, both the north and south. In recent years, observation efforts along the Platte have been further augmented by the presence of biologists employed by the National Audubon Society's Lill ian Annette Rowe Sanctuary and the Whooping Crane Habitat Maintenance Trust's Mormon Island preserve (both located along the central reach of the river), as well as the Service's regional off ice in Grand Island, Nebraska. Fran 1983 -1985 the Service, in conjunction with the Whooping Crane Trust, has made morning overflights of the Platte (f ran Chapman to Lexington, Nebraska) , during 14 to 21 days of each migration season, to search for whooping cranes roosting on the river (G. Poul l os 1985, personal comm uni ca ti on) . Though such regular scrutiny of the Platte River may be effective in more accurately documenting whooping crane use of this habitat, increased confirmed s resulting ali�� survey is may lead to misinterpretation of anarea' sreatveimpotancetomigratng whooping cranes. In view of the inherent bias in the confirmed sightings record, an important objective of radio-tracking surveys initiated l to gather more co m pl ete information on the habits of migrati ngw hoopi ngcranesatoassess 2 -16