A Nine-Year History of Furbearer Populations on the AEC Savannah River Plant Area

Abstract

The furbearer population of the 200,000-acre SRP area was censused each November for a 9-year period, 1954–1962, and also in May, 1954–1956, beginning 2 years after evacuation of the human population and abandonment of the 33% of land area which was cultivated. Ten permanent trapline locations were established, five in the Coastal Terraces physiographic zone and five in the Aiken Plateau region. Ten No. 2 steel traps set at intervals of 0.2 mile along secondary, little-used dirt roads were operated for 7 days on each census line at each census period (total of 100 trap stations). Of 533 animals of the six principal species trapped in the November censuses, gray foxes comprised 54%, raccoons 21%, bobcats 11%, red foxes 7%, striped skunks 3% and opossums 3%. The proportion of different species was not significantly different for any of the nine censuses despite a threefold variation in numbers caught. Following the very high-density level of about 12 animals per 2-mile trapline in 1954, the numbers caught remained remarkably constant at a level of 4 to 5 per trapline for the next 8 years. The per cent positive stations index for foxes on SRP during the 8-year stable period was only slightly greater than the average index in 11 rural counties of southern Georgia and northern Florida where man and agriculture were not excluded. Animals were unevenly distributed in 1954, with more gray foxes and bobcats trapped in the terraces subregion and more red foxes on the higher elevation plateau, but there was no significant difference in the catch between the 2 regions after that year. The age structure of the gray fox population in 1954–1956 indicated that the high level of 1954 was a temporary “population explosion” in an otherwise stable population. It is suggested that: (1) the 4 principal species have fluctuated as a single ecological unit, each species responsive to the same major environmental factors; (2) the rapid natural and artificial reforestation of abandoned land had not yet affected the density of furbearers and (3) in the absence of the direct influence of man in a large and ecologically diverse area, such as the SRP reservation, natural regulatory processes can maintain a steady state in density of medium-sized predatory mammals, although occasional eruptions may be expected.