PARENT SESSION
Oral Session #48: Spatial patterns, spatial processes. Presiding: D. Deutschman.
Wednesday, August 8, 2001. 1:00 PM to 5:00 PM. Madison Ballroom C.
Changes in Yellowstone National Park bison aggregation behavior as predictors of environmental state.
MEAGHER, MARY1, TAPER, MARK1, JERDE, CHRISTOPHER1, 1
ABSTRACT- From 1970 to 1997, 151 flights were taken in a fixed wing aircraft to collect data on numbers, locations, and group structure of Yellowstone National Park (YNP) bison. This population represents the only continuously wild and free ranging bison in the United States. We investigate changes over the study period in two characteristics of group structure; group size and group cohesion. We find: 1) A decrease from the 1970s to the 1990s in mean group size through time; 2) An increase over this period in the group size of highly dispersed groups, and 3) and an earlier breakdown of the breeding season aggregation. We believe that aggregation in bison reflects an interplay of the opposing forces of social attraction and response to local forage quality and quantity. We discuss the possibility of using bison aggregation behavior as a convenient measure of current environmental quality as perceived by bison.
KEY WORDS: yellowstone, bison, aggregation, Bison bison