The Phenology of Space: Spatial Aspects of Bison Density Dependence in Yellowstone National Park

The Yellowstone bison represents the only bison population in the United States
that survived in the wild the near-extermination of the late 1800's. This
population has been intensely monitored for almost four decades. The analysis
of long-term spatio-temporal data from 1970-1997 supports the following
conclusions: 1) Even though the Yellowstone bison herd exhibits an extended
period of what appears to be linear growth, this pattern can be explained with
classical density dependent dynamics if one realizes that perhaps the primary
response of the herd to increased density is range expansion. 2) Several
spatial aspects of social behavior in the YNP bison may be behavioral
adaptations by the bison to environmental changes. These behavioral strategies
may buffer, temporarily at least, bison population dynamics from the immediate
repercussions of possible environmental stress and habitat deterioration. 3)
Bison ecological carrying capacity for YNP is on the order of 2800 to 3200
animals. 4) There do appear to be indications of changes in the bison dynamics
that are associated with increasing use of sections of the interior road system
in the winter. 5) The possibility of habitat degradation is indicated.