White-Tailed Deer Diets from Pastures in Excellent and Poor Range Condition

Abstract

A study was initiated in August, 1975, to examine the forage available to and diet composition of white-tailed deer on pastures of excellent and poor range condition at the Sonora Research Station near Sonora, Texas. Grass and forb standing crop and deer feeding time on these two forage classes were considerably higher on the pasture in excellent range condition than that in poor range condition. Browse standing crop and feeding time was greater from the pasture in poor range condition. The Merrill 4-pasture grazing system appeared to increase the availability and use by deer of grass regrowth. Yearly averages of crude protein and phosphorus were higher in diet samples collected from the pasture in excellent range condition. Digestible energy levels were similar between pastures when averaged over the l-year period. Digestible energy levels in diets were, however, higher from the excellent condition pasture in every season except winter. In winter, deer fed primarily on the foliage of oak on excellent condition range; but on the pasture in poor range condition, deer used large amounts of foliage and mast from juniper and dead leaves of persimmon in addition to oak foliage. Juniper and persimmon apparently contributed to the higher digestible energy levels observed on the pasture in poor range condition during the winter season. Energy may be a major nutrient limiting deer production on the Edwards Plateau. In pristine times, the Edwards Plateau of Texas was considered a grassland steppe but has since been invaded by woody perennials (Krebs 1972). It now contains a diverse community capable of supporting many kinds of plants and animals. Among the endemic The authors are assistant professor, Department of Range and Wildlife Management, Texas Tech University, Lubbock 79409, and research associate and professor in charge, Texas Agricultural Experiment Station, Sonora, 76950. At the time of this research Bryant was research assistant, Department of Range Science, Texas AM Reardon et al. 1978), our objectives were to quantify the relationships of excellent vs. poor condition range in terms of quantity of forage available to deer and the botanical composition and nutritional quality of their diets. Study Area and Methods Two 8-ha study sites were selected at the Texas A&M University Agricultural Research Station located 45 km southeast of Sonora, Texas. One study site was selected in a pasture representing excellent range condition and the other poor range condition (Fig. I). The pastures have had different histories of use and manipulation (Table I). Topography of the Sonora Station is rolling with steep breaks along some drainages. Soils are generally stony clays and clay loams. Precipitation averages 61 cm annually with peaks in May and September.