Impact of puma predation on the decline and recovery of a mule deer population in southeastern Idaho

We modeled the impact of puma (Puma concolor (L., 1771)) predation on the decline and recovery of mule deer (Odocoileus hemionus (Rafinesque, 1817)) in southern Idaho based on estimates of puma numbers, predation rates of pumas, and reproductive variables of deer. Deer populations peaked in 1992-1993, then declined more than 55% and remained low for the next I I years. Puma numbers peaked 4-6 years after deer populations peaked but then declined to original levels. Estimated puma predation on the deer population before and after the decline was 2.2%-3.3% and 3.1%-5.8%, respectively. At high puma densities (> 3 pumas/100 km(2)), predation by pumas delayed deer recovery by 2-3 years. Percent winter mortality of fawns (r(2) = 0.62, P < 0.001) and adult female deer (r(2) = 0.68, P < 0.001) correlated positively with December-January snowfall. Incorporation of winter snowfall amounts in the model produced a pattern of deer population change matching estimated changes based on field survey data. We conclude that pumas probably were a minor factor in the decline of the deer population in our area and did not suppress deer recovery. We propose that winter snowfall was the primary ultimate and proximate factor in the deer decline and suppression of their recovery.