Deer and Cattle Diets on Heavily Grazed Pine-Bluestem Range

Abstract

We studied dietary overlap between captive white-tailed deer (n = 3) (Odocotleus tir@nlanus) and cattle (n = 4) for 3 years on 2 rotationally burned, 54-ha longleaf pine (Pinus paZustris)-bluestem (Andropogon spp.) pastures in central Louisiana. A third of each pasture was burned each year in late February. One pasture was grazed heavily (61-77% herbage use) yearlong; the other was grazed heavily (SO-67% use) from mid-April to 1 November. Deer diets were dominated yearlong by a mixture of browse (49.3~83.2%) and forbs (11.2-47.1%). Cattle consumed mostly grasses during spring and summer and 60 and 40% browse and herbage, during fall and winter, respectively. Cattle consumed more herbage on first-year burns. Dietary overlap under heavy yearlong grazing averaged 25.8, 11.8, 26.0, and 30.7% during spring, summer, fall, and winter, respectively. Overlap under heavy seasonal grazing averaged 18.5, 7.4, and 22.6% during spring, summer, and fall, respectively. Diets of both animals were diverse and overlap generally resulted from sharing small amounts of many plant taxa. Except on recent burns during summer, dietary overlap under heavy yearlong grazing was comparable to that observed under moderate yearlong grazing at half the cattle stocking rate. Moderate grazing (40-50% herbage removal) of similar range from late spring through early fall should have little negative impact on deer forage availability. Grazing during late fall and winter reduces an already limited supply of deer forage by reducing availability of evergreen browse and herbaceous winter rosettes. J. WILDL. MANAGE. 53(3):540-548 Most woodland grazing in the southern United States has been confined to the longleaf-slash pine (P. elliottid) type. Bluestem grasses dominate the herbaceous understory on about 2 million ha of this forest type in southern portions of Louisiana, Mississippi, and Alabama, and in northwest Florida. Substantial knowledge on integrated forestry and cattle management has been gathered, but questions of compatibility between catt le and wildlife, especial ly deer, have st i rred considerable debate but resul ted in l i t t le research until recently (Mitchell 1980, Thill 1984, Thill and Martin 1986). Early studies of cattle diets in the South perta in pr imari ly to the sparse ly forested bluestem and wiregrass (Aristidu stricta) ranges that developed fol lowing extensive c learcutt ing ear l ier this century. The heavy yearlong grazing and frequent (often annual) burning common earlier this century reduced availability of woody plants , which are general ly a major component of deer diets in southern states (Lay 1969). Consequently, it is not surprising that browse was generally a minor component of cattle diets in early studies (Thill 1985). Most of this cut-over range has been replanted with pines, and woody plants are now relat ively abundant as a result of less burning and grazing. Thus, early studies of cattle diets are generally not applicable to present conditions. Recent research in southern Mississippi showed that browse contributed from 2.5% of cattle diets during summer to 21.4% during winter (Mitchell 1980) . Catt le diets on rotat ional ly burned, moderately grazed pine-bluestem range in central Louisiana averaged 40.9% browse during winter, and dietary overlap between cattle and deer ranged from 8.6% during summer to 34.7% during winter (Thill and Martin 1986). Prescr ibed burning is an integral component of southern range management because it increases forage quality and production and aids in distributing cattle. Deer receive similar forage benefits and prefer recent burns (Lay 1967). Our study was conducted in 2 phases of 3 years each to evaluate dietary overlap between deer and cattle under prescribed rotational burning and several grazing treatments. In phase I, we studied deer and cattle diets in a pasture grazed moderately yearlong and deer diets only in an adjacent ungrazed pasture (Thill and Martin 1986). We also evaluated phase I treatment effects on deer nutrition (Thill et al. 1987). The object ive of this study was to quantify deer and cattle dietary overlap on pine-bluestem range under heavy seasonal and heavy yearlong grazing. We also compare phase I and phase II data. We thank W. R. Thacker and R. D. Herrick for their assistance with data collection. D. C. Guynn, Jr., R. J. Warren, J. G. Kie, and D. L.