To educate a man in mind and not in morals is to educate a menace to society. -Theodore Roosevelt
Trophy animals represent many things. For hunters who harvest an exceptional animal, trophies are the culmination of planning, dedication, and hard work. A trophy is a reminder of all the experiences enjoyed, and sometimes tolerated, during a memorable hunting trip. But a trophy is more than that. Large, mature animals are symbols of excellent habitat and sound wildlife management. They are also indicative of a natural age structure that fosters normal reproduction and thus a productive population. So suggests research in Oregon that demonstrates mature bull elk are valuable to the reproductive health of elk herds.
Scientists from the Oregon Department of Fish and Wildlife and the United States Forest Service studied an enclosed elk herd in a research area of nearly 20,000 acres. The objective was to investigate the effect of bull age on pregnancy rates and breeding dates of cow elk. During two successive five-year periods, about 400 cow elk were exposed to a cohort of bulls that began each period as yearlings and ended as 5 year-olds. About 30 cow elk were harvested each December, enabling scientists to determine if each cow was pregnant and the date she was bred.
The proportion of female elk that were pregnant was high in all years, showing that bulls of any age can successfully breed. The authors noted, however, that in the two years in which yearling bulls were breeding, nutritional conditions were exceptionally good, and it is possible that with average or poor conditions, yearling bulls may not have been as effective.
Conception date was strongly influenced by the age of breeding bulls. Average conception dates were 2 weeks earlier when breeding was done by five year-old bulls compared to yearling bulls. The first conceptions occurred in early September, regardless of bull age, but most breeding was completed around October 1 when five-year old bulls were breeding, but not until late October when yearling bulls were breeding.
What do these results mean? Mature bulls appear to be more efficient breeders than young bulls, which has several implications.
The study on which this edition of Trophy Points is based is described in:
J. H. Noyes, B. K. Johnson, B. L. Dick, J. G. Kie. 2002. Effects of Male Age and Female Nutritional Condition on Elk Reproduction. Journal of Wildlife Management 66:1301-1307.
J. H. Noyes, B. K. Johnson, L. D. Bryant, S. L. Findholt, J. W. Thomas. 1996. Effects of Bull Age on Conception Dates and Pregnancy Rates of Cow Elk. Journal of Wildlife Management 60:508-517.
"The wildlife and its habitat cannot speak. So we must and we will."
-Theodore Roosevelt