Conifer Diet Choices Made by Mule Deer (Odocoileushemionus) of North Central British Columbia During a Cafeteria-Style Feeding Trial

Abstract

The winter diets of northern mule deer are comprised predominantly of shrubs and trees. Included in winter diets are various species of conifers, some of which are important forestry and ornamental crop trees. Diet choices and feeding habits of mule deer utilizing conifer crops, however, have not been widely reported. Here, we document diet choices made by human-habituated mule deer from north central British Columbia during an exploratory cafeteria-style feeding trial using boughs of thirteen species of native North American and introduced European conifers. Mule deer consumed more biomass from exotic conifers (specifically pine) than from rarely encountered native conifers, and consumed the least biomass from those native conifers commonly encountered by deer in northern BC, a finding which appears to lend support to the Biotic Resistance Hypothesis. From most to least biomass consumed, deer selected Mugho pine, Scots pine, western hemlock, subalpine fir, Douglas fir, Norway spruce, Ponderosa pine, western white pine, lodgepole pine, common juniper, red cedar, black spruce, and hybrid white spruce. Analysis of Variance testing suggested that deer preferred to eat exotic Mugho and Scots pine and avoided eating commonly encountered, native black and hybrid white spruce. A relationship also existed between the biomass consumed and the number of bites taken by deer from each species, which generally indicated that deer took more bites from exotic and rarely encountered conifers, but not always. Our results suggest that northern mule deer, therefore, may be more likely to damage introduced pine and other exotics relative to native species planted in either ornamental or forest plantation settings when deer densities are high and/or browse resources are limited.