Background Information on Elk and Bison

Read Specifically about:  Bison, Elk, etc.
The National Elk Refuge (NER) and Grand Teton National Park (GTNP) are adjacent to one
another and are located just north of Jackson, Wyoming.  They are situated at the southern end of
the Greater Yellowstone Ecosystem.  The NER is approximately 25,000 acres and GTNP is about
304,000 acres. The elk and bison that inhabit the NER and GTNP are part of the Jackson elk and
bison herds, which comprise one of the largest concentrations of free-ranging elk and bison in
North America—approximately 13,000 elk and 1,000 bison.  The Jackson elk and bison herds
migrate across several jurisdictional boundaries including the NER, GTNP, Yellowstone National
Park, Bridger-Teton National Forest, Bureau of Land Management resource areas, and state and
private lands.  Because of the wide range of authorities and interests, the FWS and NPS are
seeking a cooperative approach to management planning involving all of the associated federal
and state agencies and a broad range of organized and private interests.

The need to begin managing the Jackson bison population is to address the increased competition
between bison and elk and other wildlife for forage, and the increased risk of habitat degradation,
disease transmission, and property damage resulting from a rapidly growing bison population.
These concerns have resulted from the following factors.

The once fenced (1948 - 1968), then free-ranging and naturally regulated (1969 - 1980) Jackson
bison herd has inadvertently become habituated to the food artificially provided on the NER for
wintering elk (bison had been extirpated from Jackson Hole in about 1840).  Because of the
artificial food source, the bison herd’s distribution has changed and the herd is artificially
concentrated during winter.  Neither winter mortality nor predators are playing a significant role
in controlling the bison population and, therefore, the population’s annual rate of increase is high
(an estimated 15 percent per year during the last 10 years).  The rapidly growing bison population
increases the potential of ecological and management problems.

Increased competition with elk and other wildlife for forage and increased habitat degradation
jeopardizes the ability of the FWS and NPS to provide the forage and habitat conditions for elk
and other wildlife that the NER and GTNP were established to protect and conserve.  The high
concentration of bison on the NER feedlines during winter creates unnaturally high levels of
disease transmission opportunity.  Some bison in Jackson Hole are infected with brucellosis.  The
disease does not currently threaten the bison population, but it does cause some mortality and it can be transmitted to domestic livestock.

As a result of a lawsuit filed in 1998, the court ordered that no destruction of bison occur on the NER or GTNP for population control purposes until the FWS and NPS analyze bison management in combination with the winter feeding program.  The court further ordered that NEPA analysis of the winter feeding program be conducted.

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Winter feeding of elk, which began in 1910 in Jackson Hole, was originally initiated to reduce
winter mortality of elk, thereby avoiding marked reductions in a population of animals important
to local residents and interest groups, as well as to minimize depredation of ranchers’ hay.
Although these immediate factors prompted the initiation of winter feeding, the need for the
NER’s winter feeding program can be traced back to reduced access to significant parts of their
native winter range.  Historically, elk that summered in the area now inhabited by the “Jackson elk
herd” wintered in the southern portion of Jackson Hole (present location of the NER and the
town of Jackson) and areas outside of Jackson Hole, including the Green River and Wind River
basins to the south and east, respectively, and the Snake River basin to the southwest in what is
now eastern Idaho.  Migration to these wintering areas probably varied significantly from year to year but little actual evidence remains to document that process.  Migrations to these wintering areas, except to southern Jackson Hole, were eventually abandoned due to settlement and other human activities outside of the Jackson Hole area.

Because of the considerable amount of snow that can accumulate in Jackson Hole in winter,
among other factors, it was not an ideal wintering area for elk.  As a consequence of reduced
migrations, compounded with the loss of available winter range in Jackson Hole to ranching operations and a growing town, significant numbers of elk died during several unusually severe winters in the late 1800s and early 1900s (prior to 1911).  This prompted local citizens and organizations, and state and federal officials in Jackson Hole to begin feeding elk in the winter of 1910-1911.

The winter feeding program on the NER has allowed the Jackson elk herd to be sustained at a
relatively large level.  As one of the two largest elk herds in the world (the northern Yellowstone
herd being the other), the Jackson elk herd has supported a large hunting, outfitting, and wildlife
viewing industry in Jackson Hole, and contributes to quality of life of people living in the area.  The Jackson elk herd has played a pivotal role in the culture and economy of the town of Jackson.  By offsetting the loss of available winter range to residential development, ranching operations on and off private lands, and other land use practices, the winter feeding of elk has contributed to high quality elk hunting opportunities on Bridger-Teton National Forest, including the Teton Wilderness area and Grand Teton National Park (GTNP).  GTNP is the only national park in the lower 48 states with a congressionally mandated public hunting program. The exceptional opportunities to view elk in GTNP and southern Yellowstone National Park is in large part attributed to the winter feeding program on the NER.

The feeding of elk on the NER has not come without cost, however.  Nearly 100 years of
concentrating thousands of elk on the refuge during five to six months each year has resulted in a
marked loss of woody plant communities, such as willow and aspen stands, which are important habitat for songbirds, moose, and mule deer.  Concentrating large numbers of animals in small areas over several months each year creates conditions that are conducive to the transmission and maintenance of currently endemic diseases as well as diseases that may be introduced in the future.  Several diseases in the elk herd are sustained at apparently higher levels than those observed in non-fed populations, but none of these diseases appear to be having significant impacts on the population.  Brucellosis is of primary concern because the disease can potentially be transmitted to domestic livestock.  Infection of livestock could have serious economic consequences for the livestock industry in Wyoming.

The removal of the natural effects of harsh winters (i.e. "winter kill") on the elk population, and the difficulty in reaching adequate harvest quotas through hunting have made it difficult for managers to maintain optimum population size.  If natural herd mortality effects of weather are continually displaced through winter feeding, more effective hunting programs will likely be necessary to maintain the Jackson elk herd within the summer carrying capacity of its available range.

A potential influence on this situation may come from increased elk predation - loss to wolves, bears, and mountain lions.  As predator numbers increase, it is likely their effects on elk population size may eventually become significantly additive to the harvest reduction.  Though estimates of maximum predator population sizes and predation rates have been developed through modeling, it is critical to monitor this situation over time to thoroughly understand the combined effects of predation and harvest on the elk population.

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