USFS
Pacific Northwest
Blue Mountains ELK NUTRITION AND HABITAT MODELS
Second generation models for management
Managing for elk requires
compromises among economic,
ecological, and recreational objectives.
To help state and federal agencies
and local communities make these
decisions, an interagency modeling
team has developed new habitat and
nutrition models that predict elk use
and nutritional conditions in the Blue
Mountains.
The models allow landowners and
public land managers to think
strategically about emphasizing (or
deemphasizing) elk habitat according
to management objectives. With their
flexibility for multi-scale analyses, the
models are useful for cooperative
planning across ownerships.
Based on recent research incorporating data from large-scale radiotelemetry studies and elk nutrition patterns, new nutrition and habitat models
offer updated science in a user-friendly format to inform land management
planning across the Blue Mountains region.
The nutrition model predicts the
nutritional value (dietary digestible
energy) of late-summer forage for
elk across the landscape—a key
driver of elk habitat use and
population health across the region.
The habitat model predicts the
level of elk use in a given area by
using estimates of late summer
nutrition from the nutrition
model combined with other
variables that affect elk use: open
roads, topography, and vegetation
composition.
To connect with practitioners and solicit their feedback, the modeling team held a workshop on April 25, 2012 in
Pendleton, Oregon. Over 140 land managers, planners, and biologists from a variety of agencies and organizations
joined the team for a day of presentations and discussions about the models and their applicability. This briefing paper
presents workshop highlights as well as feedback from participants.
September 2012
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Model context and validation
The study area includes the Blue Mountains of eastern Oregon and Washington. Model training and validation
sites include the Sled Springs and Starkey areas.
What is the new elk habitat
selection model appropriate for?
Yes
Summer range

Late summer
nutrition needs

No

Hunting season
Large regional
landscapes (20,000
to 150,000 acres)

Multiple land
ownerships

Integrated
management
strategies

Forest plan
revision guidelines

Validation with independent data sets showed a good fit with our
draft habitat use model, with predicted use by elk closely matching
observations of elk from GPS locations.
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“One of our biggest problems is
not elk numbers, but their
distribution. With the help of
these models, elk distribution
can be managed effectively
between ownerships.”
—Mike Wisdom
Can management change elk use? YES.
Management implications
The best habitat model for predicting elk use on the landscape contains four
variables: dietary digestible energy (DDE), distance to open roads, vegetation
composition, and slope. These variables were selected by a rigorous model
selection process. Variables were considered for inclusion based on their
consistency and ease of calculation, but also for their relevance to management. Other than slope, all of the selected variables are responsive to
management actions and can be altered to affect elk use on the landscape.
Distance to open roads was the strongest predictor of elk use of all the
model variables. Travel management and strategic control of access and
human disturbance will have strong effects on the patterns of elk use on the
landscape. For example, keeping human disturbance lower during early spring
can benefit elk, since the limitations of late summer nutrition increase the
importance of the high-quality forage available in early spring.
However, the nutritional bottleneck for Blue Mountains elk in late summer
does not easily lend itself to management solutions. Seasonal precipitation
patterns, typically resulting in dry soil conditions by August, greatly limit options for improving forage quality in drier vegetation types. Higher elevation
forests tend to be wetter and thus have more potential to provide nutritious
forage in summer. Opening these stands by reducing overstory, particularly
through uneven-aged treatments, can improve elk habitat.
If you have elk on your land, these models can predict where they will be
during summer and what nutritional resources are like. There are interacting
issues managers must weigh to identify where the bottlenecks are in a specific area, such as summer forage or human disturbance. The models simply
illustrate the underlying conditions that affect elk use in late summer, allowing
practitioners more information to apply their professional judgment as they
make decisions. As one practitioner said, “This is a good tool to use in
conjunction with what you already know.”
Caveat. Land managers, policy
makers, biologists, and land owners
in the Blue Mountains region face a
number of elk management concerns
in the area, some of which can be
addressed by the nutrition and
habitat models, and some of which
we lack the data to fully assess.
Issues such as livestock grazing,
predator pressure, and crop
depredation are outside of the scope
of the models.
Because of a data void, we can’t fully assess
the effects of cattle on elk distributions. It’s
an essential and unmet need for evaluating
elk summer range.
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Data and information products
Potential information products for users
Maps of elk nutrition on summer range across all lands of the
Blue Mountains
Supporting GIS files
ArcGIS programs
Users guide
What would be most useful to you? Contact us with your feedback.
The model provides a reliable, science-based
foundation for ranking habitat and using that
information to predict herd performance.
New models offer updated science
Including the importance of summer nutrition
Late summer forage conditions create a
nutritional bottleneck for elk. This concept
challenges traditional perceptions that
competition for scarce winter resources
constrains herd health and reproductive
success. The nutrition work conducted by the
modeling team has shown that female elk body
fat levels in the spring are a function of their
body fat levels from the previous fall, not how
severe the winter was. In fact, every variable
measured in their studies—calf growth, yearling
growth, adult fat levels, adult pregnancy rates,
breeding time, and winter survival—was
correlated with summer nutrition. This means
that if we have information on summer forage
quality, as displayed using the new nutrition
model, we can predict nutrition-based aspects
of herd performance. The nutrition model
provides information about nutrition resources
on summer range across all Blue Mountains
ownerships.
How you can help.
Telemetry data. For additional model training and
validation, we would like to bring in more telemetry
data sets. We are looking for information that includes unique animal identification with each location,
date, and the number of elk and locations in the data
set.
Feedback. Although the model is predicting elk use
very well, it is still a draft. We still have some
“tweaking” to do. Please send your suggestions and
questions.
Beta testing. Do you manage land for elk? Do you
have GIS experience or access to an analyst? Betatesters will get hands-on training and early access to
the models.
“The nutrition limitations of summer
range is a new idea to me. We always
thought that winter conditions were the
big management issue.” —workshop
participant
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Model application
Collaboration. These models work well for
planning at the landscape scale and across ownerships,
which are particular challenges with elk. We can use
these models to understand how to think strategically
about emphasizing elk habitat in some areas and
discouraging their use of other areas.
Weighing trade-offs. Elk habitats can benefit
from active forest management. The two models can be
useful in making decisions about combining habitat
improvements with other objectives, such as travel
management plans or thinning treatments.
Flexibility for multi-scale analyses. The
models were built to depict elk nutritional conditions
and probability of use for every 30-meter pixel across a
given landscape. Both the nutrition and habitat models
can be applied on very large areas, even the entire Blue
Mountains region. Users can evaluate these large
landscapes, including information from all landowners,
and then “drill down” to the smaller areas to evaluate
specific, local management issues. Local projects can
easily be addressed in this manner.
“Where this tool will really be useful is in coordination with other
landowners,” said one workshop participant.
Forest plan revision and more. The
models are intended for use as a regional analysis tool
to meet whatever objectives are established among
landowners. The models could be particularly helpful in
creating standards and guidelines for land management
planning, but this guidance needs to include all land
owners within a given area where management of elk
use is of strong interest. Oregon and Washington
Departments of Fish and Wildlife can also apply these
models in their wildlife units, and tribal nations can use
them to evaluate their reservation and ceded lands.
The models are not intended to be used solely
in Forest Service or Bureau of Land Management land use planning.
As one Forest Service biologist said, “A forest plan revision is
coming. We need standards for elk because they are going to
be indicators for all kinds of species. There are people working
on this every day at the district level. They need help and
information to get this right.”
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Questions from workshop participants
Can these models be used during No. These models were developed for late summer (August 1-20) only, when
hunting season?
nutritional resources for elk are at their lowest levels in the Blue Mountains.
They will not be accurate in the hunting season, or for spring or winter.
However, separate models for hunting season or spring would be possible to
develop with the data we have.
What about the effect of:
specific treatments such as
herbicide application?
prescribed burning?
livestock grazing?
predator pressure?
hikers?
Why do you truncate habitat
type classification in the nutrition
model down to only four types?
Doesn’t this ignore a lot of
variation?
Why don’t you include
agricultural lands in the model?
Is quality of forage related to
vegetation structure? Are you
predicting elk use based on
structure?
We don’t have continuous fine-scale data on specific treatments, grazing,
predation pressure, or recreational use across the regional landscapes we are
modeling. One of our goals is to make sure these models are user-friendly,
which means we need to be conscious of the availability of the data required.
A more detailed classification system might explain a little more variation, but
elk are such good “high-graders” while foraging that it takes a big difference in
plant communities for that variation to come into play. Our categorizations are
based on decades of nutrition studies, and despite having only four broad
categories of potential vegetation and the corresponding equations for
nutrition, we are still able to accurately predict elk nutritional conditions.
The distance-to-nearest-agricultural-land variable fell out early in the model
selection process. However, agricultural lands are included in the model
through the estimates of DDE in the nutrition model, which then feed into the
full habitat use model.
No. We are not modeling variation in forest structure. People sometimes
mistakenly assume we are saying that elk are seeking cover. Elk are seeking
sites that provide security and nutritious forage. Regardless of low or high
canopy cover, elk are selecting for a composite of vegetation conditions, not
just stand condition.
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Questions from workshop participants
Travel management is an
important issue for elk because
It is a good idea to test the relationship between hiding cover and distance to
of human disturbance from roads
road. We will also look into the link between forage conditions and human disand trails. Can you analyze the
turbance.
interaction between cover and
distance to road? Or forage value
and distance to road?
Why did you take location data
over a 24-hour period rather
than looking at peak foraging
times?
We could look into this by running models on peak foraging times, assigning
coefficients, and then seeing if the results become stronger. We developed the
model to be a general habitat use model for elk, not a foraging model.
The original (1979) Blue Mountains summer range evaluation methods included
How do existing elk habitat
effectiveness index (HEI) models cover/forage ratios, density of roads open to motorized vehicles, and distance
between forage areas and cover. These variables were each tested during our
compare to these new models?
model training, but none were strongly supported by the elk telemetry data we
used for the August analysis period. Most likely, elk are selecting strongly for
larger blocks of forest vegetation types, perhaps because they can forage more
efficiently in these areas.
“These models represent the first time
mapping of habitat resources has been
used to predict performance of an elk
population.” —John Cook
Management to benefit elk nutrition is likely to benefit herd
performance.
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Timeline
Westside
introductory
workshop
Corvallis, OR
Westside beta
test results
workshop
Portland, OR
Beta testing
Westside model development
2009
Blue Mountain model development
2010
2012
2011
2013
Beta testing
SW Oregon
model added
Blue Mountain
introductory
workshop
Pendleton, OR
Sponsors:
Contact:
National Fish and Wildlife Foundation
Boone and Crockett Club
Rocky Mountain Elk Foundation
Sporting Conservation Council
USDA Forest Service
Bureau of Land Management
Mary M. Rowland
Research Wildlife Biologist
USDA Forest Service
1401 Gekeler Lane
La Grande, OR 97850
541-962-6582 (voice)
mrowland@fs.fed.us
Collaborators:
USDA Forest Service, Pacific Northwest Region
USDA Forest Service, PNW Research Station
Oregon Department of Fish and Wildlife
Washington Department of Fish and Wildlife
National Council for Air and Stream Improvement
WEST, Inc.
Oregon State University
Oregon State University Extension Service
Blue Mountain
beta test results
workshop
Mike Wisdom
Research Wildlife Biologist
USDA Forest Service
1401 Gekeler Lane
La Grande, OR 97850
541-962-6532 (voice)
mwisdom@fs.fed.us
Workshop summary prepared by Rachel White, USFS PNW Station.
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