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Physical and Reproductive Characteristics of a Supplementally-Fed White-Tailed Deer Herd

1982; Wiley; Volume: 46; Issue: 2 Linguagem: Inglês

10.2307/3808640

1937-2817

John J. Ozoga, Louis J. Verme,

Reproductive Physiology in Livestock

Physiologic attributes and behavioral response of white-tailed deer (Odocoileus virginianus) in a 252-ha Upper Michigan enclosure were monitored during a 5-year period as the population increased from 23 to 159 animals supported by supplemental feeding. The ration, supplied ad libitum, augmented the natural diet except in winter, when deer ate it almost exclusively. Seasonal feed consumption was lowest at spring greenup, increased in late summer as natural forage matured, and was highest in autumn and winter. As the herd increased, deer ate progressively more of the ration per animal from July to November. Availability of summer forage gradually decreased with higher herd density. Autumn forage supply varied annually, depending upon prevailing weather. Compared to prefeeding years, better nutrition accelerated deer body growth and shortened the time to physical maturity. Except for yearling bucks, antler development improved and casting dates were delayed. In utero productivity of yearling does doubled with supplemental feeding and increased by 50% among 2.5-year-olds and 21% for older does. None of the doe fawns bred. As the population grew, harassment by bucks during the rut apparently caused an energy deficiency which lowered the productivity of yearling does. Yearling does usually conceived a preponderance of male fawns. Under the best nutritional circumstances older does regularly conceived more females. Postnatal fawn mortality gradually increased and became considerable at highest density, particularly among primiparous mothers. Doe territoriality and limited suitable fawning space probably was responsible for lowered maternal success. A marked improvement in physiological parameters after the herd was drastically reduced suggested that the aberrations observed under peak populations were density dependent. We conclude that when properly conducted, supplemental feeding provides a feasible method of maintaining a reasonably large deer herd in good physical condition with minimal damage to the range. Cost factors and recommended procedures for such programs are discussed. J. WILDL. MANAGE. 46(2):281-301 The welfare of deer in northern regions depends primarily upon their winter nutritional status. If the range is inadequate, serious losses to starvation can occur during harsh weather. More importantly, however, acute malnutrition of pregnant does commonly results in heavy neonatal mortality (Verme 1977) which can disrupt herd dynamics for years. Supplemental feeding of deer to prevent catastrophic winter-kill has been tried in many states (Bartlett 1938, Gerstell 1942, Carhart 1943, Doman and Rassmussen 1944, Hesselton 1964, Keiss and Smith 1966). Unfortunately, most of these trials were ill-conceived ventures, done on an emergency basis, offering relatively poor quality foods and/or limited amounts to animals already in starving condition. Generally, severe losses were rarely averted, and in some instances overbrowsing by high deer concentrations caused irreparable range damage. In contrast, feeding of wild cervids during winter is successfully used routinely in Europe, where populations are intensively managed and their numbers closely controlled (Dasmann 1971, Nagy and Bencze 1973, Espmark 1974). Supplemental feeding of whitetails to provide hunting stock has been done in the United States (Woolf and Harder 1979). Dire consequences have occurred where the practice was stopped (Fanter 1977). Artificial feeding of deer is probably impractical under their present management in North America. However, as noted by Dasmann (1971:69), ... it is entirely possible that changing concepts of wildlife values may alter this in the future, at least on some deer ranges. When and if public demand, new and flexible J. Wildl. Manage. 46(2):1982 281 This content downloaded from 207.46.13.132 on Tue, 05 Jul 2016 05:24:50 UTC All use subject to http://about.jstor.org/terms 282 CHARACTERISTICS OF A SUPPLEMENTALLY-FED DEER HERD. Ozoga and Verme laws, and increased funds and manpower make intensive deer management possible, regular feeding may become a standard management procedure. The present study was initiated with this philosophy in mind. Our objective was to evaluate cost: benefit of supplementally feeding white-tailed deer to achieve population levels much higher than the natural habitat could support. This work presented an opportunity to assess expected improvements in the herd's physical traits under the extra ration. Additionally, it allowed us to document changes in deer social behavior as their numbers increased, and to examine the prospective role of density stress at extreme crowding as a population control mechanism. This paper reports the response by deer to a pelleted feed, the influence of increasing herd density on existing vegetation, and changes in the physiologic and reproductive characteristics of deer during a 5-year study. Data obtained before the feeding program was implemented, and that during the 2 years following herd reduction, are included to provide a better perspective on the outcome of this investigation. The senior author thanks his wife Janice, son John Jr., and J. H. Fitch for assistance in collecting behavioral information. We are also indebted to many DNR colleagues for help in different phases of the work, especially D. L. DeLisle, C. S. Bienz, and L. J. Perry. C. L. Bennett was instrumental in originating the study. This paper is a contribution from Michigan Federal Aid in Wildlife Restoration Project W-117-R, and the Cusino Wildlife Research Station. STUDY AREA AND METHODS This study was conducted in a 252-ha enclosure (Fig. 1) near Shingleton in Michigan's Upper Peninsula. The area lies in the cold, deep snow belt along the south shore of Lake Superior, where deer typically face a long winter yarding sea-