MONTANA FISH, WILDLIFE & PARKS
FOR IMMEDIATE RELEASE - DECEMBER 16, 2005
READING ELK TEETH REVEALS DISTURBING TREND AMONG THE ELK OF
THE NORTHERN YELLOWSTONE HERD
BY -- TOM LEMKE, MONTANA FISH, WILDLIFE & PARKS BIOLOGIST IN
LIVINGSTON AND DIANE M. TIPTON, MONTANA FISH, WILDLIFE & PARKS
STATEWIDE INFORMATION OFFICER
The nationally known Northern Yellowstone elk herd, numbering
about 9,500 animals, is notably smaller, about half the size it was in the
mid-1990's. Wildlife managers recently learned that its members are
notably older, too.
Elk incisor teeth, collected from past harvests and analyzed for
age, indicate that for the first time, 50 percent of the population is nine
or more years old. That makes it an exceptionally old elk population
compared to others in the state.
"The northern herd is fast becoming a geriatric elk population
which may reduce the herd's productivity and its ability to recover from
recent population declines," said Tom Lemke, Montana Fish, Wildlife &
Parks biologist in Livingston. "The aging of this population, and the
smaller number of elk calves we're seeing survive, will continue to
influence management decisions and to reduce hunter opportunity in this
The Northern Yellowstone elk herd migrates to a winter range on
about a 590-square mile area along the Lamar, Gardiner and Yellowstone
river basins inside Yellowstone Park and north of the park in
southwestern Montana. A portion of these animals that migrate into
Montana provide hunting opportunities during the popular Gardiner late
season elk hunt set this year for Jan. 6 - 30, 2006.
Teeth from the harvested elk have been studied since 1996 by a
small laboratory in Milltown, near Missoula. There technicians carefully
section, stain, and count the cementum annuli rings they see on the roots
of the incisor teeth to determine the accurate age of each animal. The
rings in the elk teeth are analogous to the rings on a tree, each ring
marking a year of growth.
Recent analysis shows that the average age of elk harvested in
2005 during the Gardiner late season elk hunt hit record highs-8.2-years
old for cows, and 9.1-years old for bulls. Ten years ago, the average was
6.2 and 5.9 years of age respectively.
Average ages in other Montana elk populations are generally in
the range of four to five years.
"The aging of the Northern Yellowstone elk herd is an additional
factor that could make it more difficult for this herd to expand," Lemke
said. Other factors include the high number of elk calves taken by
predators, and losses of calves and adult elk to severe winter weather.
The new statewide Elk Management Plan uses the number of elk
calves that survive their first year of life to be recruited into the herd as
one guideline to determine if liberal, standard or restrictive hunting is
Here again, the Northern Yellowstone elk are struggling. Aerial
surveys indicate that, for the past four years, only 12-14 calves per 100
cow elk survived the first year of life and joined the herd. Recruitment of
about 30 calves per 100 cows is more typical for northern Yellowstone
Recent studies in Yellowstone National Park show that about
70-75 percent of newborn radio-tagged northern Yellowstone elk calves
are dead within a year of their birth, mostly due to predation. Predators
include primarily bears, wolves, and coyotes-with bears accounting for
55-60 percent of the mortality and wolves and coyotes with another
10-15 percent each.
Wildlife managers have gone from liberal, to standard, to
conservative hunting quotas over the past six years, trying to keep pace
with dynamic changes affecting the herd. Lemke said antlerless elk permit
quotas have been reduced from 2,880 in the year 2000 to 100 in 2006.
"There will probably always be debate about how many elk people
want to see in this herd. But for its overall health and viability, we know
calf recruitment needs to increase in order to see the age structure of the
herd return closer to the norm," Lemke said.
"We've reduced antlerless elk harvest quotas in an attempt to
conserve cow elk. With more adult cow elk, we hope to see an
improvement in calf recruitment, but there is a lot in this mix that we
can't control," he said.
In the meantime, studying the teeth of harvested elk to determine
the average age of the population will continue. It may seem the scientific
equivalent of reading the "tea leaves," but it is one way for wildlife
managers to evaluate over time how the Northern Yellowstone elk herd is
doing in adapting to changes in weather, habitat, predators, and hunting