Temporal and Spatial Changes in Beaver Pond Locations, Eastern Glacier National Park, Montana, U.S.A.

Sequential aerial photographs from 1966, 1973, 1984, and 1991 were used to map the number and distribution of beaver ponds in a portion of eastern Glacier National Park, Montana. The most stable ponds were located on deltaic environments. Ponds located on intermittent streams were somewhat less stable. A general equilibrium of pond number and site location exists in the study area throughoutthe 25-year period. This result contrasts with those from historical studies in eastern and central North America, where beaver populations at the turn of the century had probably been much lower than in Glacier National Park.