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Consultation Report on Yellowstone Bison Management Plan

出版	1986
URL	http://books.google.com.hk/books?id=8fwBzwEACAAJ&hl=&source=gbs_api

註釋The bison population in Yellowstone National Park has grown substantially in recent years. The most important source of mortality for this population is winter kill. A series of mild winters has undoubtedly contributed to the recent population increase. Direct measures of the carrying capacity of Yellowstone for bison are not available, but the behavior of bison indicates that the populations may be approaching the ecological carrying capacity of the environment. Bison are increasingly leaving their traditional wintering grounds and colonizing new areas. They are leaving traditional ranges earlier in the year and in greater numbers than previously, and they are moving in more directions. Some of these movements are along routes in which movement has been facilitated by winter road plowing and grooming to facilitate human movement within the park during the winter. Other winter movements, however, have begun to occur without facilitation by human activity. It seems, then, that the bison population has expanded and is dispersing, a normal sequence in wildlife species and one that is normally desirable. --First paragraph.