Yellowstone Elk: Conservation and Management

Whitney Tilt, Conservation Chatter, September 2016

Bull elk with cows (photo courtesy of Gallatin Wildlife Association)

ELK in the Greater Yellowstone

The Greater Yellowstone Ecosystem (GYE) is home to approximately 30,000–40,000 elk. Nine discrete herds, totaling 10,000-20,000 animals compose the Greater Yellowstone “superherd” whose summer range is in the core protected area of the GYE. Come winter, the majority of these animals will migrate to lower elevations, outside the park, while some will remain in the same area year-round. 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 their vernal migration while in years with lower snowpack and earlier vegetation green-up, elk migrate earlier. There is growing evidence that elk are changing their migratory habits in response to predators: bears, wolves, mountain lions and human hunters. Map depicts the general location and migratory routes of the nine elk herds.

The dynamics of the Paradise Valley herd is highly dependent on private lands and its seasonal migrations have become more constrained. The Northern Herd is the best known and studied herd (along with the Jackson Herd), and the impact of wolves and hunting on population numbers continues to be sharply debated. The Madison Herd summers in and around the Madison Range, and winters in large groups on the high benchlands of the Madison Valley.

 BIOLOGY/ECOLOGY

Elk (Cervus elaphus) are one of the most abundant large mammals found in the GYE, and they are a vital contributor to the ecology of the region: as prey for large carnivores, carrion for scavengers, and consumers of vegetation. Elk are also an economic mainstay for hunting and tourism in the states of Montana, Wyoming, and Idaho. It is not an overstatement that elk define and unify the GYE, both ecologically and culturally.

 While North American’s elk is the same species as Europe’s red deer, the name “elk” is actually the European word for moose. Small wonder that European visitors can get confused on visiting Yellowstone. The species is perhaps better labelled “wapiti,” Shawnee for “white deer” or “white-rumped deer.”

Bull elk weigh about 700 pounds and stand some five feet high at the shoulder; cow elk weigh some 500 pounds and are slightly shorter. Calves are about 30 pounds at birth; born May to late-June, overlapping with periods of peak vegetation green-up and high-nutrition plant phases allowing mothers and calves to build up fat reserves. Elk feed on grasses, sedges, other herbs and shrubs, as well as aspen sprouts and bark, conifer needles, and aquatic plants.

In the fall, bull elk bugle to attract cows and challenge other bulls for dominance. The bugle is not so much a bugle coming from a brass horn as a bellow building to a squeal, terminating in a grunt (listen at https://elknetwork.com/elkfacts/). Dominant bulls gather cows and calves into small groups or harems and then aggressively guard these harems against all comers.

ANTLER MANIA

Bull elk grow massive racks which begin growing in the spring in response to a depression of testosterone levels and lengthening daylight. Yearling bulls grow antlers for about 90 days while healthy, mature bulls grow theirs over a +/- 140 day period. In the later stage of growth, antlers of a mature bull will grow 0.66 inches per day reaching 60” or more in length and weighing some 30 pounds per pair. During much of the summer, “velvet” covers the antlers -- a thick, fuzzy coating of skin, which nourishes and deposits the calcium that forms the antler. Antler growth typically ends in early August, and the bulls begin scraping the velvet off, polishing and sharpening the antler tines in preparation for the coming rut (mating season) in September and October.

Bulls retain their antlers through the winter. When antlered, bulls usually settle disputes by wrestling with their racks. 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. Antlers are dropped annually, in March-April, and the process begins anew.

courtesy of arthur middleton

NORTHERN HERD DYNAMICS

The Northern Elk Herd is Yellowstone’s largest herd. Its summer range is centered in the area of the Lamar and Yellowstone River valleys, north of Yellowstone Lake, from Soda Butte to Gardiner, Montana. In winter the herd migrates north outside of the park into the Gallatin National Forest and the lower elevation private lands. With more moderate temperatures and less snowfall than the park interior, the Paradise Valley and surrounds supports large numbers of wintering elk. 

For decades, debate raged over too many elk and the disappearance of willow and aspen from the Lamar Valley and elsewhere. Control of a burgeoning elk population was one of the main arguments for returning the gray wolf as it would provide a year-round predator to control elk numbers and keep them more dispersed across the landscape.

The winter count was approximately 17,000 when wolf reintroduction began in 1995. The number fell below 10,000 in 2003 and 3,914 were censused in 2013 -- the lowest since culling ended in the park in the 1960s. Decreased numbers are attributed to large carnivore recovery (wolf, bears, mountain lion), hunter harvest, and drought-related effects on pregnancy and survival. A total of 4,844 elk were counted in winter 2015 with the expressed hope that the elk decline has stabilized as efforts to maintain wolf numbers have also been implemented (graph).

Winter counts of the Northern Elk Herd in Yellowstone National Park and adjacent areas of Montana, 1960–2016. Counts are not adjusted for elk sightability, and gaps represent years where no official count was conducted. Source: NPS.

There is little doubt that the return of gray wolves have altered elk behavior -- group sizes, habitat selection, movements, distribution, and vigilance. There are some indications that elk–wolf interactions are contributing to a release of willows and other woody vegetation on the northern range. At the same time, the debate continues over the overall condition of the Northern Yellowstone range and its carrying capacity, with several range specialists continuing to point out that the range is seriously overstocked by bison and elk.

DISEASE

Many elk and bison in the Greater Yellowstone Ecosystem have been exposed to the bacterium that causes brucellosis. Brucellosis is a contagious bacterial disease that originated in livestock and often causes infected cows (cattle and elk) to abort their first calves. It is transmitted primarily when susceptible animals directly contact infected birth material. No cure exists for brucellosis in wild animals.

Because of their high densities, elk that are fed in winter have sustained high levels of brucellosis. Winter feeding on the Northern Range stopped more than 50 years ago but winter feeding of elk continues at the National Elk Refuge in Jackson, Wyoming, in addition to 22 Wyoming-run feed grounds. The feed grounds were created in the 1900s to maintain Wyoming’s elk herds and limit depredation as migratory routes from summer range to lower elevation winter ranges became blocked by settlement in the Jackson area. Transmission of brucellosis from feed ground elk, where an average of 30% have tested positive for exposure to the bacteria, was the apparent source of infection in Wyoming cattle in 2004.

Elk, deer, and moose in Greater Yellowstone are at moderate risk for exposure to chronic wasting disease (CWD). This fatal infection, transmitted by animal contact or through the environment, has spread to within 130 miles of the park from the southeast.

FALL HUNTING & SHED HUNTING

The “Welcome Hunter” banners hanging on the front of local taverns, gas stations and restaurants, and the “No Vacancy” signs at local motels in the fall signal the importance of big game hunters, both resident and non-resident, to Idaho, Montana, and Wyoming’s economy. In 2016, big game hunters in Montana spent an estimated $324 million and supported more than 3,300 jobs.

 *Includes license, tags, and processing fees for 2016Shed hunting, the hunting of the cast-off antlers of elk, deer, and moose, has become increasingly popular in recent years, leading to more competition among shed hunters, more conflicts with private landowners from trespass and vandalism, and more impact on big game herds. State Wildlife Management Areas and ranchers are reporting a growing number of incidences. There have even been reported cases where individuals have run antlered elk through trees in early spring in the hope of breaking off antlers.

Currently there are no seasons or required licenses for shed hunting. But that may change as many shed hunters take to the field to gather antlers during the worst time of the year for the animals themselves. Wintering big game animals are very susceptible to any kind of disturbance, especially in the late winter and early spring. At that time of year elk, deer and moose are just trying to hang on until spring green-up, drawing from their diminished body reserves and what little nourishment they can get from surrounding vegetation (like conifer needles and bark). Disturbance from passing motorists, snowmobilers, skiers, dogs, or shed hunters, who intentionally or unintentionally enter areas where elk are bedded down, depletes the little energy the animals have left. This stress and energy depletion leads to sickness and oftentimes death, especially for fawns and calves at this critical time of year.

Ethical shed hunting focuses on not disturbing big game animals on their bedding grounds, respecting public land closures and posted private lands, keeping dogs under control.

Horns or Antlers?

Antlers, found on members of the deer family, grow as an extension of the animal’s skull. They are true bone, are a single structure, and, generally, are found only on males.

Horns, found on pronghorn, bighorn sheep, and bison, are a two-part structure. An interior portion of bone (an extension of the skull) is covered by an exterior sheath grown by specialized hair follicles (similar to human fingernails).

Antlers are shed and regrown yearly while horns are never shed and continue to grow throughout an animal’s life. One exception is the pronghorn, which sheds and regrows its horn sheath each year.

The average, healthy, mature bull has 6 tines on each antler, and is known 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.

Resources and References

On the Path of Yellowstone’s Elk, Nathan Martin. The Atlantic, June 21, 2016. 

Yellowstone Resources and Issues Handbook. National Park Service U.S. Department of the Interior.

Yellowstone. National Geographic, May 2016