Experimental Analysis of Methods for Measuring Small Mammal Populations

Abstract

The Peromyscus leucopus on a 17-acre study area were live-trapped, marked, and released over a seven-day period. On the 3 following nights intensive snap-trapping was done on the central acre of the study plot. The animals caught by snap traps in the central acre represented the population of the central acre and several surrounding acres. By the currently accepted methods of interpreting snap-trap data, the population would be considered to be 23 adults per acre. The live- ; trap data show conclusively that the true population was between 6 and 7 adults per acre. Modern methods of live trapping are shown to be valid for population studies. Two methods are presented for the conversion of live-trap data into per acre figures. Errors involved in the current use of snap-trap data are discussed and snap trap methods are shown to be invalid means of determining actual population numbers.