Condition Parameters of White-Tailed Deer in Texas

Abstract

Physical condition in 2 herds of white-tailed deer (Odocoileus virginianus texanus) was assessed through postmortem analysis of weight, fat, antler, whole blood, and blood serum. One herd was existing at a normal population density and the other was artificially maintained at a high density within a 391-ha predator exclosure. Adult deer within the predator exclosure had lower values for bled carcass weight, eviscerated carcass weight, kidney fat index, femur marrow fat, paired adrenal gland weight, number of antler points, hemoglobin, serum creatinine, iron, albumin, and alkaline phosphatase than those outside the exclosure. Fawns within the exclosure had lower eviscerated carcass weights and higher relative adrenal weights and blood urea nitrogen levels. Body weights, kidney fat, and femur marrow fat were the best indicators of physical condition when postmortem sampling was done. J. WILDL. MANAGE. 47(3):583-594 Previous studies of white-tailed deer on the 3,157-ha Rob and Bessie Welder Wildlife Foundation Refuge in south Texas documented high mortality rates among newborn fawns, primarily because of coyote (Canis latrans) predation (Knowlton 1964, White 1966, Cook et al. 1971). An intensive predator control program, initiated in 1973 within a fenced 391-ha study area, was successful in increasing fawn survival. As a result, deer population density increased. Counts by helicopter in January 1975 yielded density estimates of 81 deer/km2 inside the predator exclosure, but only 40 deer/km2 on surrounding areas outside the exclosure. In 1976, estimated densities were 64 deer/km2 inside the predator exclosure and 49 deer/ km2 outside (Kie 1977, Kie et al. 1979). Deer inside the predator exclosure exhibited lower reproductive rates, delays in conception and parturition, longer antler velvet retention, earlier shedding of hardened antlers (Kie et al. 1979), greater grass and less forb consumption, lower levels of rumen-content crude protein, and increases in rumen calcium-to-phosphorus ratios (Kie et al. 1980). These differences suggested that deer within the exclosure were on suboptimal nutrition and were in poorer condition. Measures of body weight were among the 1st-used indicators of physical condition in deer. Body weight was related to range conditions by Johnson (1937), Park and Day (1942), Severinghaus (1955), and others. These authors also suggested that antler measurements were useful indicators of the relationship between range quality and deer numbers. Qualitative and quantitative measurements of fat stores have also been used to assess physical condition in deer and other mammals. However, fat may be deposited in several forms and locations throughout the body (Pond 1978). In the past, analyses have included examination of rump and other subcutaneous fat, total abdominal fat, fat surrounding the kidneys (Riney 1955), combined indices of subcutaneous and visceral fat (Kistner et al. 1980), lipid content of bone marrow (usually from the femur in ungulates) (Cheatum 1949), and blood serum lipid concentraIA contribution of the Pacific Southwest Forest and Range Experiment Station and the Welder Wildlife Foundation (WWF #271). J. Wildl. Manage. 47(3):1983 583 This content downloaded from 157.55.39.102 on Mon, 03 Oct 2016 06:25:35 UTC All use subject to http://about.jstor.org/terms 584 WHITE-TAILED DEER CONDITION PARAMETERS * Kie et al. Table 1. Monthly and weighted yearly mean age, weight, fat, and blood values of adult white-tailed deer outside and inside a predator exclosure, Welder Wildlife Refuge, July 1975-May 1976.