Use of Rio Grande Plain brush types by white-tailed deer and analysis of influents

Abstract

The relative use of 11 major brush types and a rootplowed area by white-tailed deer (Odocoileus virginianus) was studied on the San Pedro Ranch in Dimmit County, Texas, using the pellet-group count technique. The hackberry drainage, mesquite drainage, and guajillo scrub were types selected by deer for use in fall, winter, and spring. In summer all types except mesquite drainage were used about equally, the latter being clearly selected for. Two types, granjeno drainage (sparse herbaceous vegetation) and rootplowed, were selected against by deer most of the time. A feature of the three preferred brush types was the presence of mesic forbs not found in abundance anywhere else. A least squares analysis showed the parameters of site most associated with dense pellet-groups were plant dominance, forb density, grass density was highly significant. Pellet-group abundance was greatest where leatherstem (Jatropha dioica) and guajillo (Acacia berlandieri) shrubs were dominant, where forbs and grasses were dense and on sandy loam soils. Pellet-group means associated with interaction of forb and grass densities showed that dense stands of forbs and grasses were about equally attractive. None of the structural attributes of brush attracted deer. White-tailed deer show a wide range of tolerance to density and composition of woody plant species on uncleared land and respond more to herbaceous density. Range sites capable of high gross production of herbaceous plants deserve consideration for their value to deer in brush clearing schemes. Leaving some brush intact on this type of land should insure continuing deer populations on ranches practicing brush control.