Breeding behavior and performance of yearling (1.5 years) white-tailed (Odocoileus virginianus) bucks was compared to that of prime-age sires by removal of either buck class in each of two 3-year trials, using a supplementally fed herd in a 252-ha enclosure. Yearling males dispersed from ancestral range coincident with the breeding season, even in the absence of sexual competition from older bucks. Compared to the pre-rut (Sep-Oct) and rut (Nov) behavior of older bucks, yearlings associated in larger mixed groups, interacted more aggressively with both sexes, displayed less courtship behavior, and demonstrated delayed and less scent-marking behavior. Despite differences in age-related rutting behavior, the lack of ritualized performance among yearling sires was not detrimental to doe reproductive success. Complete exploitation of prime-age bucks provided no evidence of short-term deleterious effects on herd productivity. J. WILDL. MANAGE. 49(2):364-372 Intense interest in deer hunting and recent liberal harvest policies have created concern regarding the impact of heavy exploitation on herd welfare in Michigan (Langaneau and Aho 1983) and elsewhere. Because bucks are particularly vulnerable during the rut (Roseberry and Klimstra 1974, McCullough 1979:74) and are hunted preferentially or sometimes exclusively, comparatively few sexually mature males survive when hunting pressure is high. Distortion of age ratios in one or both sexes under such conditions reportedly disrupts the social order of some ungulates to the point of impairing their reproductive performance (Bubenik 1972). The potential consequences of social disorder among white-tailed deer, however, have received scant attention (Woodson et al. 1980), particularly as it applies to the female segment of a herd (Ozoga and Verme 1984). Physically mature bucks typically dominate younger subordinates to the extent that only a relatively few individuals in a given area do most of the breeding (Hirth 1977). Stable dominance hierarchies are established through agonistic behavior prior to the rut, thus minimizing overt conflict during the breeding period (B own 1974). In contrast, yearling bucks generally disperse to new range during autumn (Hawkins and Klimstra 1970, Hawkins et al. 1971, Kammermeyer and Marchinton 1976). These subdominant floaters (Brown 1974:437) associate loosely with various male groups, int ract aggressively, presumably do little breeding, and on occasion disrupt the population's social order (Townsend and Bailey 1981, Ozoga and Verme 1982). This suggests that yearling bucks are not as reproductively effective as older animals should a mating opportunity arise. Our objective was to evaluate the breeding behavior and performance of yearling white-tailed bucks compared to prime-age sires, by removal of either buck class in each of two 3-year trials. This paper is a contribution from Mich. Fed. Aid in Wildl. Restoration Proj. W-127-R, and the Cusino Wildl. Res. Stn. We thank J. L. Ozoga, C. S. Bienz, and R. K. Clute for collecting behavioral data and L. J. Perry, D. L. DeLisle and other Dep. Nat. Resour. personnel for valuable assistance. C. L. Bennett, G. E. Burgoyne, K. R. McCaffery, D. R. McCullough, and T. W. This content downloaded from 157.55.39.112 on Wed, 07 Sep 2016 05:14:55 UTC All use subject to http://about.jstor.org/terms J. Wildl. Manage. 49(2):1985 DEER BREEDING BEHAVIOR * Ozoga and Verme 365 Table 1. Population characteristics of supplementally fed white-tailed deer in a 252-ha Upper Michigan enclosure. Reintroduced population (Mar) Fawns Males Females Surviving Autumn Years Juva Ada Juv Ad Total In utero >1 month N 1977 2 10 6 26 44 46 45 89 1978 2 8 9 23 42 46 37 79 1979 0 6 4 25 35 47 40 75 1980 8 0 11 19 38 37 23 61 1981 7 0 9 21 37 40 31 68 1982 8 0 10 22 40 41 35 75 a Juveniles were then 9 months old, adults were -21 months old. Townsend provided helpful criticism of the manuscript. U. S. Seal and E. D. Plotka provided technical support. Figures were drafted by G. F. Lehman.
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