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Sandhill Crane Study in the Central Flyway

Raymond J. Buller

出版	U.S. Department of the Interior, Fish and Wildlife Service, Bureau of Sport Fisheries and Wildlife, 1967
URL	http://books.google.com.hk/books?id=w9hti0MY1_0C&hl=&source=gbs_api
EBook	FULL_PUBLIC_DOMAIN

註釋

Fall-migrating sandhill cranes arrived at congregation sites in southern Canada and in the States of the Central Flyway between late July and early October. Sandhills peaked at about 100,000 birds at way stations during the fall of 1964. Footprint measurements indicated that the lesser sandhill was by far the most numerous subspecies at way stations in Montana, North Dakota, South Dakota, and Colorado. These measurements also indicated that flocks stopping over in Wyoming, Kansas, and Oklahoma contained a significant number of Canadian sandhill or greater sandhill or both. A selective collecting program indicated that the footprint measurement technique overemphasized the incidence of the greater sandhill at way stations in North Dakota and South Dakota. Whooping cranes and sandhills were occassionally observed together during the early part of the fall migration. At times, fall-migrating sandhills fed on standing and harvested grain crops in Canada and hte States of the Central Flyway, but seldom were depredations considered serious.