Mule Deer Regions - No Two are Alike
Map of Mule Deer Ecoregions in the West
No two mule deer populations are alike because where
they live differs from one part of their range to another.
Biologists refer to the different areas as “ecoregions”.
By studying each ecoregion, biologists can better identify
the factors that are limiting the growth of mule deer
populations, and predict responses by mule deer populations to
changes in habitat. Habitat quality has an effect on survival of fawns,
the most important factor in determining how well a population fares
from season to season, and year to year.
Biologists have identified seven ecoregions that mule deer call
home. Each ecoregion is briefly summarized including a physical
description, a description of the deer, the climate, limiting factors
that reduce the productivity of deer,
and recommendations to improve
mule deer populations.
All ecoregions are subject to the
limiting factors such as urbanization,
fire suppression and drought
described in this publication.
The limiting factors listed for each
ecoregion in this article are some of
the most important, but certainly not
the only factors, limiting mule deer
populations.
Although each region is ecologically
different, some common
factors exist:
- Generally, habitats conditions that
are less productive for mule deer.
- Human caused factor such as fragmentation
of habitat, changes in fire
regimes, livestock management and
changes in plant communities have
limited deer populations.
- Return to higher mule deer numbers will require stronger land
use planning and restoration efforts on a large scale.
- Climate and weather play an important role in habitat quality
in each region.
Coastal Rain Forest
Ecoregion
Description: Along the west
coast of North America from
northern California through
southeast Alaska. Known for its
dense rain forests of western
hemlock, Sitka spruce and natural
and commercial forests of Douglas
fir. Clearcutting is common in
commercial forests, and provides
excellent habitat for mule deer
for eight to 10 years after harvest
when grass, forbs, shrubs and
saplings are common. In the
northern part of this region where
winter snowfall can be heavy, it is
important to retain stands of
mature trees to intercept the snow.
 Climate: A marine climate with
cloudy days, cool temperatures,
high precipitation from fall to
spring, and a short, dry summer
season. Precipitation ranges from
25 to 120 inches. Soils are coarse
and nitrogen-poor.
The deer: Black-tailed deer are
the dominant subspecies of mule deer. The deer are primarily nonmigratory,
and are well distributed
and occur at the greatest densities in
early successional habitats in the
central and southern part of the
region. In the northern part of this
ecoregion, deer numbers are greatest
on coastal islands, where marine
weather lessens the severity of
winter. In the far north, winter snow
may force deer to lower elevations.
Black-tailed deer are often unable
to meet their nutritional requirements
year round. Fawns rarely
breed, and pregnancy rates for
yearlings vary greatly from year to
year, but are generally low.
Deer in this region tend to be
older than in other regions because
the amount of secure cover deer
find in the dense forest limits hunter
success.
Limiting Factor: The quality of
the plants. Heavy rainfall and soils
poor in nitrogen cause nutrients to
leach from the soil, and plants have
more moisture. Pound for pound,
a deer consumes less nutrients while
foraging in coastal rain forest than in
other regions.
Recommendations:
1. Create more grass, forb, shrub and
sapling communities to improve
food quality.
2. Maintain forest canopies in places
where snowfall is heavy.
3. Manage forests for high quality
plant foods to allow for large harvest
of deer to reduce overwintering populations,
and thus reduce browsing on
young conifers.
4. Survey for diseases and parasites.
5. Plant mast producing species such
as oak in dry and southern areas.
6. Conduct small, cool controlled
burns.
California Woodland
Chaparral
Description: Includes the
Coast Range of southern
California, and lower elevations of
the west slope of the Sierra
Nevada east into central Arizona.
 Climate: Hot dry summers,
mild wet winters, and periodic
droughts create annual grasses and
forbs in communities of oak woodland
and chaparral. Precipitation
ranges from 8 to 30 inches a year.
Chaparral was once maintained by
frequent, cool fires, but fire suppression
created older stands of
chaparral with poor quality forage.
The deer: Mule deer populations
in this region do not migrate,
except for those at higher elevations
in the Sierra Nevada and
San Gorgonio Mountains. Deer
densities are greatest in the
northern part of this ecoregion.
Nonmigratory deer move in
response to changes in habitat on
north and south facing slopes.
Limiting factors: Fire. Most of
the mule deer range in this region
is in private ownership, and fire
suppression is a high priority for
residents. This region is in a fireadapted
habitat, and frequent fires
occurred before European settlement.
Frequent fires rejuvenate the
habitat and improve forage for
mule deer. Fire suppression results
in infrequent, large, hot fires. The
lack of fire results in older, less
nutritious plants for mule deer.
Weather. Summer and early fall
is a difficult time for mule deer
because of little rainfall, and dry
plants with little nutritional value.
Nursing does need high quality
forage to nurse fawns and build
body reserves for the coming
winter.
Recommendations:
1. Use fire to stimulate sprouts of
shrubs over a large landscape.
2. Stimulate new growth of
desired plants using light
livestock grazing.
3. Minimize effects of livestock
along streams and uplands to
improve forage for mule deer on
fall and winter ranges.
Southwest Deserts
Ecoregion
Description: Includes the
southern portions of California,
Arizona, New Mexico and west
Texas, extending into northern
Mexico.
 Climate: This region is arid to
semi-arid, and has extreme temperatures,
high evaporation rates,
low rainfall that varies greatly from
year to year, periodic droughts and
poor soils. Precipitation ranges
from 5 to 20 inches annually.
The deer: Deer are nonmigratory
and greatly affected by
droughts. Fawn recruitment is
variable depending on amount and
timing of rainfall. During dry years,
fawn recruitment is typically
below what is needed to maintain
the population.
Limiting factors: Rainfall and
competition with livestock. Winter
rainfall affects the diversity, quality
and quantity of next years' spring
forbs, which directly affects the
number of young deer that are
born and survive to adulthood.
Winter precipitation stimulates
plant growth in the spring. Forbs
are critical to the survival of deer
in this ecoregion because browse
plants don't contain adequate
amounts of nutrients.
Competition with other forb and
grass-eating species such as livestock
can have a great effect on mule deer,
especially during years when rainfall
is limited and range resources are
scarce. Overgrazing in drought years
can have long-lasting effects.
Recommendations:
1. Create sources of water in areas
where water is limiting and where
other potentially limiting factors are
being addressed.
2. Monitor grazing so that livestock
do not remove large amount of
plants, particularly in years where
drought or other climatic conditions
stress deer.
3. Work with landowners to provide hunter access to public land.
4. Monitor human sprawl.
Great Plains Ecoregion
Description: The largest grassland
ecosystem in North America,
extending from central Canada to
the Texas panhandle, west to the
Rocky Mountains. The region
includes a transition from tallgrass
to shortgrass prairie.
 Climate: This region is semiarid,
annual precipitation varies
between 10 and 33 inches, and
temperature varies greatly.
The deer: Mule deer in this
region are nonmigratory, although
they shift their home range in
response to local moisture conditions
that affect plant quality. Mule
deer forage on agricultural plantings
in areas that are irrigated.
Limiting factor: Cover.
Drought and severe winter snows
can affect mule deer populations.
Fire is important in maintaining
grasslands.
Draws that contain shrubs,
hardwoods and moisture provide
mule deer with critical habitat,
especially in the winter. Grassland
and shrub/grassland communities
interspersed with draws provide
critical year-round habitat for mule
deer. Irrigated fields grow nutritious
grasses for mule deer forage.
Human activities are a doubleedged
sword for mule deer. While
agriculture provides watering holes
and alternative food sources for
mule deer, overgrazing by livestock
is harmful to the woody
draws that provide cover and
moisture.
Recommendations:
1. Work with landowners to minimize
the effects of severe weather
conditions by providing hard
woody cover for mule deer by
improving grazing strategies and
riparian habitats.
2. Provide hunting opportunities
consistent with habitat conditions
and deer populations.
Colorado Plateau
Shrubland and Forest
Ecoregion
Description: High elevation areas in western Colorado, eastern
Utah, southern Wyoming, and
northern Arizona and New
Mexico. Habitat ranges from
spruce trees at high elevations,
ponderosa pine and Douglas fir at
mid-elevations, and sagebrush and
pinyon-juniper at lower elevations.
 Climate: Much of this region is
above 5,000 feet and includes
many mountain peaks above
15,000 feet. Precipitation ranges
from 8 to 24 inches. Winters can
be severe.
The deer: Deer are migratory
because of the heavy winter snowfalls
at high elevations. Deer populations
are most affected by severe
winters that cause nutritional stress,
high fawn mortality and lower fawn
recruitment. Some lower elevation
ranges can be summer range limited.
Livestock grazing may affect the
quality of forage available to deer.
Limiting factors: Severe winters
and droughts can impact the productivity
of mule deer by causing high
fawn mortality.
Improper livestock grazing has
caused changes in mule deer winter
range.
Recommendations:
1. Limit disturbance to existing winter
range, and acquire additional
winter range.
2. Improve quality and quantity of
winter range habitat.
3. Maintain stands of aspen for mule
deer fawns and summer range.
4. Limit development of and disturbance
to summer range in areas
where summer range is limiting.
Intermountain West
Ecoregion
Description: The mountain
ranges west of the Rockies, east of
the Sierra Nevada, north of
Colorado and south of Canada.
The Great Basin, a large semiarid
basin, makes up a big part of this
land mass. Pinyon-juniper woodlands,
conifer forests and aspen
woodlands are common at higher
elevations.
 Climate: Lower elevation communities
receive less than 12 inches
of precipitation a year. Areas to
the north and at higher elevations
receive most of their precipitation
as snow.
The deer: If you could draw a
bull’s-eye around the portion of
the West that was once the center
of mule deer distribution, you
would draw it around this region.
Mule deer typically migrate in this
region (although some do not),
spending summer in conifer forests
at higher elevations and winter in
lower elevations. Deer densities
are highest in places where vegetation
and topography are diverse.
Agriculture and urban development
have hurt mule deer populations
in this region by destroying
shrub communities and reducing
winter range.
Limiting factors: Competition
with livestock, agriculture, urban
development and timber management.
Each year, thousands of
acres of sagebrush habitat and valleys
are being overtaken by pinyon-
juniper stands, much to the
detriment of mule deer.
In the southern part of the
region, invasive plants such as
cheatgrass and changes in fire
cycles are limiting mule deer productivity.
Habitat in spring and summer
affect mule deer productivity more
than severe winters because the
quality of spring and summer
range affects the number of fawns
surviving to adulthood. Urban
development may affect recruitment
because it is occurring in
mule deer winter range.
Recommendations:
1. Manage motorized traffic to benefit
mule deer.
2. Manage forests for both early and
late successional stages to meet
year-round needs of mule deer.
3. Protect and plant important
browse species for mule deer, especially
in winter ranges.
4. Manage wildfires on mule deer
ranges to avoid cheatgrass invasion.
5. Manage livestock grazing to minimize
impacts to mule deer along
streams and in aspen habitats.
6. Develop cost-effective ways to
reduce pinyon-juniper invasion,
and place a priority on developing
a patchwork of habitats so that
mule deer have woody cover near
places to forage.
Northern Forest
Description: The higher elevations
of the Cascades and Sierra
Nevadas in the three most western
states, as well as northern Idaho,
western Montana and Wyoming,
northern Washington, and the
western Canadian provinces.
Pine, spruce, fir, Douglas fir and
larch are the dominant forest
types, and forests become more
thin as elevation increases. Mule
deer are not found very far north
of the northern boreal forest in
subarctic woodlands.
 Climate: Winters are long and
cold. Average annual precipitation
varies with elevation and topography,
from 10 inches to as much as
120 inches.
The deer: Because of severe
winters and heavy snowfall, most
of the deer in this region are
migratory, although some are yearround
residents at lower elevations.
The growing season is short,
and the quality of food mule deer
find during this critical time is
high. Deer follow retreating snow
in search of food.
Limiting factors: Severe winters.
Deer follow the growth of
plants throughout the growing season.
It is only when severe winters
and deep snow limit their ability to
forage that they experience die-offs
and high mortality.
If mule deer populations
experience a die-off, there is excellent
chance for recovery as a result
of spring and summer habitat
conditions.
The greatest threats to deer in this
region are development and disturbance
of winter range, and barriers
to migration.
Recommendations:
1. Acquire winter range habitat and
minimize housing developments to protect and enhance winter ranges.
2. Use fire to maintain shrubdominated
habitats.
3. Maintain forest shrubs, forbs,
grasses and saplings to provide
foraging habitat in spring, summer
and fall.
4. Avoid and manage forest encroachment
into high elevation meadows.
5. Avoid barriers to migration.
6. Manage deer populations based on
the ability of winter range to support
them, and avoid overharvest in years
when early winters send migratory
deer to lower elevations.
Mule Deer, Changing Landscapes, Changing
Perspectives, is a series of non-technical articles based on
technical papers from the book, “Mule Deer Conservation: Issues and
Management Strategies” Published by The Berryman Institute, Utah
State University.
The contents of this web page may be
photocopied or reprinted for noncommercial purposes using the
citation listed below:
Mule Deer Working Group. 2003. Mule Deer:
Changing landscapes, changing perspectives. Mule Deer Working Group,
Western Association of Fish and Wildlife
Agencies.
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