Ore. October 21, 2010. The availability of highly nutritious forage
is one of four factors linked to the presence of elk populations
in western Oregon and Washington, according to a modeling study
recently completed by scientists from the U.S. Forest Service’s
Pacific Northwest (PNW) Research Station. Findings from the two-year
study will be used to update land management planning for the ecologically
and economically important ungulate in the region.
Habitat models like the one we developed are critical to managing
elk populations, particularly since current management practices
are based on decades-old research and are in the process of being
updated to reflect new science,” said Mary Rowland, a wildlife
biologist at the station’s La Grande Forestry and Range Sciences
Laboratory and one of the study’s principal investigators. “Findings
from our modeling go a long way in explaining where in western
Oregon and Washington elk populations are most likely to thrive.”
and colleagues used a nutrition model based on elk grazing trials
that predicts dietary digestible energy (DDE), a variable
that represents nutrition levels based on plant community types.
The model was developed by John and Rachel Cook, biologists with
the National Council for Air and Stream Improvement, and measures
DDE during the summer—a crucial time for elk that ultimately
impacts their survival and reproduction rates. The model can also
be used to generate maps depicting areas of the landscape that
offer the greatest nutritional resources and the effects of forest
on nutrition levels.
The scientists then used DDE predictions in
combination with over 50 additional model variables to investigate
actual patterns of
elk habitat use in western Oregon and Washington. By using radiotelemetry
locations of elk, primarily from tribal sources, from five years
across three study areas, Rowland and her colleagues identified
variables that consistently provided the most support for observed
habitat selection patterns of elk—DDE, distance to roads
open to public access, percent slope, and distance to cover-forage
The new elk habitat model was then validated by comparing its output
to radiotelemetry observations from five additional study sites.
Our results were extremely encouraging, with close matches seen
between predicted elk use from the model and locations of elk
in the study
areas,” said Mike Wisdom, a PNW Station research wildlife
biologist, also in La Grande, who initiated the project. “This
information can help set goals for changing elk use in certain
areas and guiding
management prescriptions for elk habitat.”
This fall, biologists
with the Forest Service’s Pacific Northwest
Region, the Oregon and Washington State Office of the Bureau of
Land Management, Oregon Department of Fish and Wildlife, Washington
of Fish and Wildlife, and the Muckleshoot Indian Tribe will be
testing the elk habitat model and providing feedback to the researchers.
Rowland and her colleagues are planning to expand their modeling
effort to southwest Oregon beginning next year.
The PNW Research Station is headquartered in Portland, Oregon.
It has 11 laboratories and centers located in Alaska, Oregon, and
Washington and about 425 employees.