15. Proportion of Drakes in Mallard Flocks along the Lower 

 Yellowstone River, 1974 and 1975 53 



16. Aerial Censuses of Great Blue Heron Rookeries on the 



Lower Yellowstone River in 1975 and 1976 61 



17. Area of Vegetation Types on All Islands within Each 



Section of the Lower Yellowstone River 66 



18. Length of Shoreline per Vegetation Type in Each Section of 



the Lower Yellowstone River 67 



19. Size Classification, Number, and Frequency of Islands within 

 Sections of the Lower Yellowstone River 69 



IX 



