Efficacy of Permanent and Temporary Pellet Plots in Juniper-Pinyon Woodland

Abstract

porary unmarked plots for surveys of ungulate fecal pellet-group densities (Neff 1968). Here we report on estimating densities of mule deer (Odocoileus hemionus) pellet groups using both permanent and temporary plots in an area of juniper-pinyon (Juniperus osteosperma-Pinus edulis) woodland. Temporary plots have been considered to have several inherent problems. Errors in determining numbers of new pellet groups could be significant as subjective differentiation of new from old groups not previously cleared from plots would be necessary (Neff 1968). However, Ferguson (1955), Robinette et al. (1958), and Rogers et al. (1958) concluded that new groups could be subjectively distinguished from old groups provided surveys were conducted during spring. Temporary plots varying annually in location may introduce an important source of variability in estimating pellet-group densities and they could also be placed with bias if established by pacing (Robinette et al. 1958). In spite of these concerns, use of temporary and permanent plots to estimate pellet-group densities has not been directly compared. Temporary plots are attractive because of their low cost. They would also facilitate changes in sampling systems that might otherwise be precluded if permanent plots were established. Our objective was to compare estimates of mule deer pellet-group densities on 10cadastral mi2 (2.59-km2) sample units (SU) using equal numbers of permanent (PERM) and temporary (TEMP) plots. The study was conducted from 1977 through 1980 in the Piceance Basin of northwestern Colorado.