Grazing and Burning Impacts on Deer Diets on Louisiana Pine-Bluestem Range

Abstract

Diets of 3-5 tame white-tailed deer (Odocoileus virginianus) on adjacent ungrazed and continuously grazed (35% herbage removal by late Oct) forested pastures were compared for forage-class use, botanical similarities, foraging selectivity and efficiency, and diet quality. Both pastures were divided into 3 burning subunits and burned in late February on a 3-year rotation. Botanical composition of diets differed between and within pastures, but forage-class use was similar except during winter, when deer selected more browse on ungrazed subunits. Grazing had no effect on dietary protein, phosphorus (P), or calcium (Ca) levels, but diets from ungrazed subunits were higher in digestibility (except during summer) and contained more uncommon plant taxa. Deer foraged more efficiently on grazed than on ungrazed subunits but were less efficient on recent than on older burns. Diets from 1st-year burns were higher in protein during spring and summer and higher in P during spring. J. WILDL. MANAGE. 51(4):873-880 Forested rangelands dominated by longleaf (Pinus palustris) or slash (P. elliottii) pine and bluestem grasses (Schizachyrium spp. and Andropogon spp.) occupy about 2 million ha of the southern Coastal Plain. Cattle have grazed southern forests since the 16th Century, but public land managers increasingly are under pressure from wildlife and environmental groups to curtail grazing due to its perceived detrimental effects on wildlife, especially white-tailed deer. Research to resolve this controversy began only recently (Thill and Martin 1986). Prescribed burning is an integral part of forest, wildlife, and cattle management in the South, This content downloaded from 157.55.39.27 on Wed, 07 Sep 2016 05:11:13 UTC All use subject to http://about.jstor.org/terms 874 CATTLE, BURNING, AND DEER DIETS * Thill et al. J. Wildl. Manage. 51(4):1987 but its effects on deer and cattle interactions have only recently been investigated (Thill 1984a, Thill and Martin 1986). Burning usually increases forage availability and nutrient content, and deer and cattle prefer to graze recent burns (Duvall and Whitaker 1964, Lay 1967). Late winter burning on a 3-year rotation is a common management practice for cattle. The abundant rainfall, high temperatures, and heavily leached, acid soils of the southern Coastal Plain produce an abundance of native forage of limited nutritional value. Many native forages are deficient in P all year (Blair et al. 1977) and adequate in protein only during spring for optimum deer growth (Short 1969, Thill and Morris 1985). The objective of this study was to determine effects of burning and grazing on deer diets. Specifically, we compared deer diet composition and nutritional data over a 3-year period from 3 rotationally burned subunits of a pasture receiving moderate yearlong grazing to those obtained on 3 subunits of an adjacent, rotationally burned, ungrazed pasture. Comparisons included forage-class use, botanical similarities, foraging efficiency, diet selectivity, and diet qual-