Evidence for a trade-off between growth and body reserves in northern white-tailed deer

Abstract

We contrasted patterns of growth and accumulation of body reserves in autumn between two high-density (HD) white-tailed deer populations facing winters of different severity and length. Both populations occurred in the absence of effective predators and suffered from some forage competition based on reduced body masses. A third population living at low density (LD) and confronting long and severe winters (SW) served to distinguish the influence of food competition and winter severity on growth and body reserves. We estimated body components (water, protein, fat and ash) of deer during the first half of November and compared growth patterns between sexes and regions. HD-SW males continuted growth to an older age than HD males facing short and mild winters (MW) but females of both regions reached adult body mass at the same age. LD-SW deer exhibited a growth pattern similar to that of HD-SW animals but were the heaviest and the largest, suggesting that growth patterns are related to winter harshness (or length of the growing season) and that final body size is related to forage competition in summer. Sexual dimorphism became evident at an older age in the HD-SW population than in the HD-MW population, demonstrating that winter harshness does not affect immature males and females in the same manner. Fawns from the HD-SW population had proportionally longer legs and a higher percentage of body fat. Adaptations of immature deer to long and severe winters suggest that survival during the first winter represents the most critical step in the life span of northern white-tailed deer.

Contributions of forage competition, harvest, and climate fluctuation to changes in population growth of northern white-tailed deer

“…Given the maritime influence on climate in Nova Scotia, much of the winter snowfall melts shortly after falling (Canadian Climate Program 1993). It is snow accumulation and not snowfall that actually limits deer in winter (Ozaga and Gysel 1972;Mech et al 1987;Lesage et al 2001). Thus the NAO may correlate better with annual snow accumulation (for which data were not available) than with gross snowfall.…”

Density-dependent responses of fawn cohort body mass in two contrasting roe deer populations

“…3). Lesage et al (2001) have previously shown that body mass and size of white-tailed deer (Odocoileus virginianus) fawns were higher in populations experiencing severe winter conditions. Further, large animals are able to accumulate a disproportionately larger amount of fat than smaller individuals (Peters 1983), and since individuals with the largest fat reserves and fasting endurance will suffer least winter mortality, there will be strong selection towards larger body size in northern areas (Lindstedt and Boyce 1985).…”

Summer Diet of Two White-tailed Deer, <em>Odocoileus virginianus</em>, Populations Living at Low and High Density in Southern Québec

“…size because growth and replenishment of body reserves occur during this period of the year (Hjeljord and Histol 1999;Lesage et al 2001;Boucher 2004).…”