Threats to Wildlife and the Platte River

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p. 14 WILDLIFE population occurs in the Big Bend area between Kearney and Grand Island. Most of the remaining cranes use the Overton -to -Elm Creek and Sutherland -to -North Platte areas, with some congregating at the Lewellen area upstream of Lake McConaughy on the North Platte (USFWS 1981, p 19). The length of river that Sandhill Cranes now occupy "is markedly reduced from former periods. Cranes have abandoned the 60.5 - mile... reach between the Tri- County Canal intake and its discharge site near Overton. Much of this reach was probably lost in the decade immediately following dewatering of much of the channel in 1941... (T)he advanced development of woody vegetation at many sites along this reach has resulted in a disjunct crane distribution" ( Krapu 1982, p 546). East of Kearney, to Grand Island, the channel remains relatively wide, averaging 200 yards, and approximately 300,000 cranes use the area for roosting ( Krapu 1982, p 546). Table 2A details the relationship between channel width and Sandhill Crane use. Cranes show a clear preference for wide channels; 70 percent of crane use occurred in channels wider than 166 yards even though these channels made up only 25 percent of the available habitat ( Krapu 1981). Table 2A Relationship Between Channel Width and Sandhill Crane Use Channel Width % Crane Use % Of River Available 0 -54 yards (0 -49 m) 1 18 55 -165 yards (50 -150 m) 29 57 166+ yards (151+ m) 70 25 (Source: Currier et al. 1985, p 41. from Krapu 1981). A good case in point is when cranes stopped using roosts on the Red River in Oklahoma during the winter of 1969 -1970 when woody growth constricted most of the channel to less than 100 meters (Lewis 1976 in Krapu et al. 1984). Although "cranes will temporarily roost on dry land when wetland sites are not available, [s]ites lacking a water barrier ...do not provide secure roosting habitat for staging cranes" ( Krapu et al. 1984).