Influence of age of males and nutritional condition on short- and long-term reproductive success of elk.

Abstract

Rocky Mountain elk (Cervus elaphus) populations in some areas of northeastern Oregon have experienced declines in spring calf to cow ratios of nearly 80 percent over the last 40 years. Among the potential causes of these declines, the effects of age of male sires and the nutritional condition of females on conception dates and pregnancy rates have received the most attention from biologists and wildlife managers. Reliance on younger males as primary breeders can result in later conceptions and a prolonged rut period (Follis 1972; Hines and Lemos 1979; Noyes et al. 1996, 2002). Mechanisms involved with delayed conception due to male age have included late maturity of young males (Hines et al. 1985), female preference for older males (Gibson and Guinness 1980, Squibb 1985) and delayed timing of estrus in the absence of older males (Komers et al. 1999). The rate of conception (pregnancy), rather than the timing, does not appear to be dependent on the presence of older male sires (Follis 1972; Noyes et al. 1996,2002).

Citation

Noyes, James H.; Johnson, Bruce K.; Dick, Brian L.; Kie, John G. 2004. Influence of age of males and nutritional condition on short- and long-term reproductive success of elk. In: Transactions of the 69th North American Wildlife and Natural Resources Conference: 572-585