Rocky Mountain Elk

Three elk run across a grassland.

NPS/Corey Lycopolus

 

 

 

Valles Caldera is home to the second largest elk herd in New Mexico. These animals provide visitor enjoyment, revenue to local economies, and sustenance for families. Primarily grazers, elk have a diverse habitat range but are often found in open grasslands or meadows near forest edges. In mountain regions, they generally stay in higher elevations during warmer months and migrate to lower elevations in the winter.

Elk are an important food source for bears, mountain lions, coyotes, and numerous scavenger species. Elk browsing and nitrogen deposition can affect vegetative production, soil fertility, and plant diversity. Thus, changes in elk abundance over space and time can alter plant and animal communities at Valles Caldera.

 

Scientific Name

• Rocky Mountain elk, Cervus canadensis nelsoni

Population at Valles Caldera

• 2,500-3,000

Where to See

• Summer: Valle Grande, South Mountain, Valle de los Posos, Valle Jaramillo
• Autumn, during “rut” or mating season: Valle Grande, Rabbit Mountain, South Mountain
• Winter: migrate to lower elevation areas like Banco Bonito, Redondo Meadow, and near the communities of Los Alamos and Jemez Springs

Size and Behavior

• Males (bulls) weigh ~700 pounds and are ~5 feet high at the shoulder; females (cows) weigh ~500 pounds and are shorter; calves are ~30 pounds at birth.
• Bulls have antlers, which begin growing in the spring and usually drop in March or April of the following year.
• Feed on grasses, sedges, other herbs and shrubs, bark of aspen trees, conifer needles, burned bark, aquatic plants.
• Mating season (rut) in September and October; single calves born in May to late June.

 

Description

Elk are the most abundant large mammal found at Valles Caldera. European American settlers used the word “elk” to describe the animal, which is the word used in Europe for moose (causing great confusion for European visitors). The Shawnee word “wapiti,” which means “white deer” or “white-rumped deer,” is another name for elk.

Due to their huge antlers, bull elk are one of the most photographed animals at Valles Caldera. Bull elk begin growing their first set of antlers when they are about one year old. Antler growth is triggered in spring by a combination of two factors: a depression of testosterone levels and lengthening daylight. The first result of this change is the casting or shedding of the previous year’s “rack.” Most bulls drop their antlers in March and April. New growth begins soon after.

Growing antlers are covered with a thick, fuzzy coating of skin commonly referred to as “velvet.” Blood flowing in the skin deposits calcium that makes the antler. Usually around early August, further hormonal changes signal the end of antler growth, and the bull begins scraping the velvet off, polishing and sharpening the antlers in the process.

The antler-growing period is shortest for yearling bulls (about 90 days) and longest for healthy, mature bulls (about 140 days). Roughly 70% of the antler growth takes place in the last half of the period, when the antlers of a mature bull will grow two-thirds of an inch each day. The antlers of a typical, healthy bull are 55–60 inches long, just under six feet wide, and weigh about 30 pounds per pair.

Bulls retain their antlers through the winter. When antlered, bulls usually settle disputes by wrestling with their antlers. When antlerless, they use their front hooves (as cows do), which is more likely to result in injury to one of the combatants. Because bulls spend the winter with other bulls or with gender-mixed herds, retaining antlers means fewer injuries sustained overall. Also, bulls with large antlers that are retained longer are at the top of elk social structure, allowing them preferential access to feeding sites and mates.

 

Elk Antlers

• Antlers are usually symmetrical and occur on males, or very occasionally females.
• The average, healthy, mature bull has 6 tines on each antler, and is known in some parts of the US as a “six point” or “six by six.”
• One-year-old bulls grow 10–20 inch spikes, sometimes forked.
• Two-year-old bulls usually have slender antlers with 4 to 5 points.
• Three-year-old bulls have thicker antlers.
• Four-year-old and older bulls typically have 6 points; antlers are thicker and longer each year.
• Eleven- or twelve-year old bulls often grow the heaviest antlers; after that age, the size of antlers generally diminishes.

 

Mating Season

The mating season (rut) generally occurs from early September to mid-October. Elk gather in mixed herds—many females and calves, with a few bulls nearby. Bulls bugle to announce their availability and fitness to females and to warn and challenge other bulls. When answered, bulls move toward one another and sometimes engage in battle for access to the cows. They crash their antlers together, push each other intensely, and wrestle for dominance. While loud and extremely strenuous, fights rarely cause serious injury. The weaker bull ultimately gives up and wanders off.

Bulls retain their antlers through the winter. When antlered, bulls usually settle disputes by wrestling with their antlers. When antlerless, they use their front hooves (as cows do), which is more likely to result in injury to one of the combatants. Because bulls spend the winter with other bulls or with gender-mixed herds, retaining antlers means fewer injuries sustained overall. Also, bulls with large antlers that are retained longer are at the top of elk social structure, allowing them preferential access to feeding sites and mates.

 

Wildlife Observing Truly wild, truly amazing

 

Population

The high-elevation grasslands of the park provide summer habitat for 2,500–3,000 elk. However, fewer spend the winter months in the park. Climate is an important factor affecting the size and distribution of elk herds. Many ungulates migrate to increase their access to high-quality food. They prefer to feed on young plants, which are the most nutritious. In winter, colder temperatures and snowfall decrease the amount of forage that grows, which means less forage is accessible to wildlife. This forces elk to migrate to areas where forage is more available. The timing and routes of elk migration closely follow the areas of seasonal vegetation growth and changes in snow depth. After winters with high snowpack, elk delay migration. In years with lower snowpack and earlier vegetation green-up, elk migrate earlier.

Ungulates that migrate typically give birth around periods of peak vegetation green-up to overlap with high-nutrition plant phases. Nutritious food allows mothers and calves to build up fat reserves. Changes in climate will undoubtedly impact newborn elk, but it is difficult to predict whether that impact will be positive or negative. Earlier spring could lead to a longer snow-free season where migration and access to food are not encumbered. However, a longer growing season, without increased access to high-quality forage, might have a negative impact. Warmer temperatures could increase the rate of green-up, causing the plants to complete their growth cycle faster, thus shortening the period of time that food is available and accessible. Also, earlier spring could result in a mismatch in the timing of calving and the date of peak plant nutrition, resulting in high mortality of newborn calves.

 

 

Resources

Barber, S.M., L.D. Mech, and P.J. White. 2005. Yellowstone elk calf mortality following wolf restoration: Bears remain top summer predators. Yellowstone Science 13(3): 37–44.

Barmore, W.J. Jr. 2003. Ecology of ungulates and their winter range in northern Yellowstone National Park, Research and Synthesis 1962–1970. Yellowstone Center for Resources.

Garrott, R.A., et al. 2005. Generalizing wolf effects across the greater Yellowstone area: a cautionary note. Wildlife Society Bulletin 33:1245–1255.

Garrott, R.A., P.J. White, and F.G.R. Watson. 2008. The Ecology of Large Mammals in Central Yellowstone: Sixteen Years of Integrated Field Studies In Terrestrial Ecology Series. London, UK: Academic Press, Elsevier.

Houston, D.B. 1982. The Northern Yellowstone Elk: Ecology and Management. New York: Macmillan Publishing Co.

National Research Council. 2002. Ecological Dynamics on Yellowstone’s Northern Range. Washington, DC: National Academy Press.

White, P.J., and R.A. Garrott. 2005. Northern Yellowstone elk after wolf restoration. Wildlife Society Bulletin 33:942–955.

White, P.J., and R.A. Garrott. 2005. Yellowstone’s ungulates after wolves – expectations, realizations, and predictions. Biological Conservation 125:141–152.

White, P.J. et al. 2003. Evaluating the consequences of wolf recovery on northern Yellowstone elk. Yellowstone Center for Resources.

White, P.J., et al. 2005. Yellowstone after wolves – EIS predictions and ten-year appraisals. Yellowstone Science 13:34–41.

White, P.J., K.M. Proffitt, and T.O. Lemke. 2012. Changes in elk distribution and group sizes after wolf restoration. American Midland Naturalist 167:174–187.

White, P.J., R.A. Garrott, K.L. Hamlin, R.C. Cook, J.G. Cook, and J.A. Cunningham. 2011. Body condition and pregnancy in northern Yellowstone elk - evidence for predation risk effects? Ecological Applications 21:3–8.

White, P.J., K.M. Proffitt, L.D. Mech, S.B. Evans, J.A. Cunningham, and K.L. Hamlin. 2010. Migration of northern Yellowstone elk - implications of spatial structuring. Journal of Mammalogy 91:827–837.

White, P.J., R.A. Garrott, and G.E. Plumb, eds. 2013. Yellowstone’s Wildlife in Transition. Cambridge, Massachusetts: Harvard University Press.

White, P.J., D. R. Stahler, D. W. Smith, D. R. MacNulty, and R. A. Garrott. 2023, In press. Northern Yellowstone Elk: Resilience and Adaptation to Changes in Management Policies and the Ecosystem.