Antler Characteristics and Body Mass of Spike- and Fork-antlered Yearling White-tailed Deer at Maturity

We compared antler characteristics and body mass at 4.5 years of age (adult) of 140 white-tailed deer (Odocoileus virginianus) reared in a captive herd at the Kerr Wildlife Management Area (Hunt, Texas) from 1973 to 1990. Each yearling (1.5 years old) was classified as spike- (N = 43) or fork-antlered (N = 97), and its live body mass recorded. Fork-antlered yearlings were further partitioned into 3-5 points (N = 33) and ≥6 points (N = 64) subclasses based on the number of antler points ≥2.54 cm in length. All deer were reared in 1.62-ha enclosures and maintained on a 16% crude protein diet ad libitum. In ensuing years, antlers were removed and live body mass recorded. At 4.5 years, the gross Boone and Crockett (GBC) score of each buck was measured. The average GBC score of adult deer that were fork-antlered yearlings (127.8 ± 2.0 SE) was greater (P <0.001) than those of spike-antlered yearlings (89.9 ± 2.8). This difference arose from increases (P <0.001) among fork-antlered yearlings relative to spike-antlered yearlings in the average score of 4 GBC components. Adults that had forked antlers as yearlings also had greater (P <0.001) tine lengths and beam circumferences than did adults that were spike-antlered yearlings at each of the 4 GBC measurement positions. Mean body mass of fork-antlered yearlings was greater (P <0.001) than that of spikeantlered yearlings at both 1.5 years (54.0 ± 0.7 vs. 43.6 ± 1.0 kg, respectively) and 4.5 years (78.7 ±1.0 vs. 66.7 ±1.6 kg). When fork-antlered yearlings were partitioned into 3-5 points and ≥6 points classes, the GBC scores at maturity of the 3 classes of yearlings differed significantly (P <0.05). Average GBC scores of adults that had ≥6 points as yearlings (134.0 ± 2.3) exceeded that of adults that were spike-antlered as yearlings by 44 GBC points; and all GBC components differed (P <0.001) among the classes of deer. Our results show that classifying yearlings as either spike- or fork-antlered was useful for predicting antler characteristics and body mass at maturity, and that spike-antlered bucks continued to produce smaller antlers at maturity in our controlled population.

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