Limited observations of cranes in winter wheat fields and reports from 

 wheat ranchers indicate that use of this crop type by large flocks of 

 migrating cranes is common. Smaller flocks were less commonly observed in 

 corn and alfalfa fields near the river. Migrating cranes also stopped to 

 roost at night on stockponds and along the river. 



The most heavily-utilized crane migration corridor crosses the Yellowstone 

 River between Hysham and Fallon. Within that corridor, most of the cranes 

 observed during the study passed over the river between Rosebud and Kinsey. 

 The largest number of cranes observed passing over the Yellowstone in both 

 1974 and 1975 were observed during the third week in October. In 1974, the 

 earliest and latest observations of cranes passing through the study area were 

 on October 5 and November 12, respectively, and in 1975, on September 30 and 

 October 27, respectively. 



OTHER SPECIES 



All other species of large migratory birds observed during this study are 

 listed in appendix F. Observations of these species indicated whether they 

 nested in the study area, occurred only as fall and/or spring migrants, or 

 if they summered or wintered in the area. 



ISLAND AND VEGETATION ANALYSIS 



The total area of selected vegetation types on islands, and the length 

 of shoreline of these same types, within all sections of the study area are 

 shown in tables 17 and 18, respectively. These vegetation types were 

 quantified to delineate possible relationships between the numbers of the major 

 migratory bird species present in a given section and the area and shoreline 

 length of the types in those same sections. The absolute measurements were 

 standardized by dividing them by the thalweg length in each section. 



Land recently cleared for grazing on islands and along the main banks 

 was uncommon in all sections. Agricultural acreage on river islands was 

 nonexistent or small in all sections, although agricultural land did comprise 

 some portion of the main shoreline in all sections. The cottonwood-grassland 

 and dense cottonwood types occurred along the main shoreline in measurable 

 areas in all sections except the Terry-to-Fallon section, where cottonwoods on 

 the river bottom are scarce (figure 25). The cottonwood-grassland type did 

 not occur in measurable areas on islands in the Zero-to-Powder River and Terry- 

 to-Fallon sections because of the lack of large, forested islands in those 

 sections (table 19). The dense cottonwood type did not occur in measurable 

 acreages on islands from Kinsey to Fallon; the sparsity of riparian vegetation 

 in this section is also shown in the scarcity of shrubs on shorelines and on 

 islands. The sagebrush-grassland vegetation type was more prevalent on islands 

 and along shorelines in the downstream portion of the study area. 



Although no significant correlations were found between the numbers of 

 Canada geese and bald eagles and the vegetative parameters measured in each 

 section, some relationships were apparent which were not shown by these 

 correlations. Aerial censuses of breeding geese indicated that little goose 



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