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RELATIONSHIPS AMONG MULE DEER AND THEIR PREDATORS
Fact Sheet #1
RELATIONSHIPS AMONG MULE DEER AND THEIR PREDATORS
Fact Sheet #1
OVERVIEW
Relationships between predator and prey abundance are complex and not easily described. Under certain conditions,
predators may influence fluctuations in mule deer populations and affect the goals that managers set for a specific
population. Only by understanding the complexity of predator and prey relationships will it be possible to determine
if or when management of predators will be effective in helping mule deer populations.
BACKGROUND
Mule deer are prey for many large predators of western North America. In the western U.S. and Canada, those
predators are primarily mountain lions, coyotes, and bobcats, although black bears, wolves, grizzly bears, and feral
dogs will also take mule deer. Predators can have a limiting or regulating effect on mule deer populations. However,
many factors interact to influence mule deer abundance, and predation is only one part of the equation. Predator
control is simply the removal of predators. Predation management is any activity that may influence the relationship
between predators and their prey, including habitat enhancement to increase prey security and lethal removal of
predators. In most cases, reducing the number of predators to increase mule deer populations is inefficient and cost
prohibitive. Therefore, predator control should only be instituted when circumstances indicate a high likelihood of
management success, and where specific and measurable objectives can be applied and carefully monitored.
When mule deer populations are close to carrying capacity, predation tends
to have less influence on the population, and reductions in predator numbers
are unlikely to result in an increase in the mule deer population. When habitat
conditions are favorable, mule deer have better nutrition and more cover, which
reduce susceptibility to predation. Likewise, winter habitats with deep snow
can limit mobility and increase vulnerability to predation. When alternate prey
species occupy the same habitats as mule deer, predator populations have more
prey from which to select. In those instances when mule deer numbers decline,
predators may switch to other prey, thereby reducing effects of predation on
remaining mule deer. Conversely, this ability to switch prey may maintain
stable or high predator numbers, which can in turn limit mule deer population
growth when below their carrying capacity. In mule deer range with multiple
predators, those predators may compete with one another, which may influence
predator abundance (e.g., increased coyote numbers may result in decreased
bobcat numbers). In short, the relationships between predator and prey
are complex, difficult to isolate and characterize, and rarely result in simple
management solutions.
AZGFD - George Andrejko
THE INFLUENCE OF PREDATORS
The influence of predators on mule deer populations is variable and based on several factors that include:
1) Relationship of the mule deer population to the carrying capacity of the habitat,
2) Overall habitat condition,
3) Abundance and distribution of alternate prey populations, and
4) Number, abundance, and distribution of predator species that inhabit mule deer range.
Kim Morton
RELATIONSHIPS AMONG MULE DEER AND THEIR PREDATORS
Society places varying values on predators and the role that they play in an ecological setting. Wildlife management
agencies typically develop outreach plans that include media releases, public meetings, and educational campaigns
to help people understand not only predator-prey relationships, but also differing views about predator-management
programs. A common misperception among hunters is that simply removing some predators will lead to increased
mule deer numbers. In practice, predator removal to benefit mule deer populations is only effective under a few
specific conditions.
USING SCIENCE TO GUIDE MANAGEMENT
In reviewing scientific research on predator control, there were similarities in cases where predator control was
effective at improving deer populations. In general, predator control has been effective when:
1) Predation was identified as a limiting factor,
2) Predator control was implemented when deer populations were below habitat carrying capacity,
3) Control efforts reduced predator populations sufficiently across the landscape to yield results (e.g.,
expected to be about 70% of a local coyote population),
4) Control efforts were timed to be most effective (just prior to predator or prey reproduction),
5) Control occurred at a focused scale (generally <250 mi2).
Many factors must be considered prior to implementing a predation management program, including:
1) Development of a management plan that identifies:
a.
Current status of mule deer populations relative to carrying capacity,
b.
Factors that may be playing a role in reducing mule deer populations,
c.
Deer population objectives desired through predation management,
d.
Desired population reduction goals for the predator species,
e. Scale of the predator control effort,
f. Timing, method, and budget for predation management efforts,
g.
Public outreach plan.
2) An adaptive-management plan should include how predator and prey populations will be monitored to
determine when goals have been achieved or how management programs can be adjusted.
More information on mule deer can be found at www.muledeerworkinggroup.com
Ballard, W. B., D. Lutz, T. W. Keegan, L. H. Carpenter, and J. C. deVos, Jr. 2001. Deer-predator relationships: a review of recent North American
studies with an emphasis on mule and black-tailed deer. Wildlife Society Bulletin 29:99–115.
A product of the Mule Deer Working Group - Sponsored by the Western Association of Fish & Wildlife Agencies - Approved July 2013
Produced with support from the Mule Deer Foundation (www.muledeer.org)
RELATIONSHIPS AMONG MULE DEER AND THEIR PREDATORS
Fact Sheet #1
UNDERSTANDING MULE DEER AND WINTER FEEDING
Fact Sheet #2
Starvation of wild animals is part of nature. Virtually all
wild animal populations experience significant and dramatic
population fluctuations. Human compassion makes people want
to help mule deer with winter-feeding programs. Changing
nature by winter feeding is a complex matter involving numerous
issues to be considered before determining a course of action.
BACKGROUND - Supplemental winter-feeding programs, despite broad social appeal and acceptance, are expensive, can
negatively affect mule deer behavior and biology, and save very few deer. Inadequate habitat and severe winter weather
with heavy snow accumulation and cold temperatures are the ultimate cause of most winter-feeding programs. Prior
to initiating winter feeding, the potential for long-term benefits to mule deer as well as habitat conditions needs to be
critically evaluated.
BIOLOGY - Several unique aspects of mule deer biology complicate the potential for successful winter feeding. Unlike elk,
mule deer are highly selective foragers, at least in part, due to their specialized digestive system. As “ruminants,” mule deer
rely on a very complex stomach system to aid in digestion. Mule deer use bacteria in their rumen to aid in the digestion of
their food. Specific types of bacteria are required for specific types of food, therefore the type of food required for winter
feeding of mule deer is highly limited, very specific, and must be properly formulated. Because the digestive system can’t
adapt quickly enough, supplementally fed mule deer may die with full stomachs. This is especially the situation when
starving mule deer are fed alfalfa hay, corn, or other traditional livestock feeds.
BEHAVIOR - Mule deer behavior may also be negatively affected by winter-feeding efforts. Behaviors important to mule
deer survival include learned behaviors, such as foraging and migratory habits; both critical to the long-term sustainability
of a population. Winter-feeding has the potential to disrupt both winter foraging activities and migratory patterns.
As mule deer learn locations of feeding stations, they continue to visit these sites, sharing this information with each
successive year’s offspring. As each generation becomes more reliant on artificial food sources, they become less familiar
with natural foraging sites and activities. Additionally, mule deer may fail to recognize the need for migration.
DISEASE AND PREDATORS - Winter-feeding programs generate artificially high animal densities at feeding sites. These
high densities of animals provide ideal opportunities for the transmission of diseases and parasites. Winter feeding in
areas highly populated by humans may create significant liability issues in terms of attracting predatory animals such as
mountain lions and domestic dogs.
COMPETITION - Mule deer compete fiercely for food when it is limited. Consequently, the biggest, strongest, healthiest
deer, such as dominant does, exclude the truly “needy” individuals (usually fawns) from the food. By placing a resource
in a localized area, competition is increased and some deer get little or no food, while others gorge themselves and get too
much. Too much of a supposed “good” thing can also jeopardize their survival due to complications from dietary shock.
UNDERSTANDING MULE DEER AND WINTER FEEDING
SOCIOLOGY - Sitting by and watching mule deer die from starvation is not something most of us are willing to do.
Both proponents and opponents of winter feeding believe they have the deer’s best interest in mind. However, even well
designed and executed winter-feeding programs often fail to significantly increase the chance of mule deer survival.
Even if winter feeding could save a few deer from starvation, we must consider the biological cost to the habitat, cost to
other species, and cost to mule deer in the long term. We must focus on the sustainability of the mule deer population
for generations to come – not just one season. Another problem resulting from the initiation of feeding by private
citizens is the desire to continue feeding at times of the year mule deer don’t “need” it but will choose to stay on it, further
complicating the concerns outlined above and often providing food sources that may ultimately kill deer. Uncoordinated
or casual feeding efforts result in dozens of different foods being fed, while deer migratory habits, foraging behavior, and
fear of humans are also negatively affected. Feeding can attract deer into landscaped yards and high traffic areas, causing
damage to gardens and increasing vehicle accidents. People who feed deer often ignore the real issue of availability and
condition of natural habitats. They believe supplemental feeding, can adequately meet mule deer nutritional needs.
CONCLUSIONS - Government agencies in western North America have conducted supplemental feeding of wildlife
for about 100 years. At best, feeding has a limited nutritional benefit, often negated by undesirable, even catastrophic,
behavioral and biological effects. Of course, we all have the best interest of wildlife in mind. However, we must ensure we
understand the biology of the animals we’re concerned about so our actions are truly beneficial. This is often the point of
debate as society considers winter feeding mule deer. Our conventional wisdom, experience, and professional consensus is
clear - feeding mule deer violates the most basic principle of population regulation within natural systems. At best, winter
feeding for mule deer is only successful in making people who are compassionate about wildlife feel better and seldom are
any benefits of winter feeding realized.
Winter feeding of mule deer creates artificially
high concentrations of animals, leading to increased
risks, including disease transmission and predation.
Winter-fed mule deer often die with full
stomachs due to their inability to adapt to
rapid changes in type and abundance of feed.
More information on mule deer can be found at www.muledeerworkinggroup.com
A product of the Mule Deer Working Group - Sponsored by the Western Association of Fish & Wildlife Agencies - Approved July 2013
Produced with support from the Mule Deer Foundation (www.muledeer.org)
RELATIONSHIPS AMONG MULE DEER AND THEIR PREDATORS
Fact Sheet #1
OVERVIEW
Mule deer need open landscapes to make a living. They move long
distances daily and seasonally, and highways that cross mule deer
ranges can be an obstacle to those movements. Many mule deer are
killed on highways and many more have restricted their daily and
seasonal ranges to avoid crossing busy highways. State and provincial wildlife and transportation agencies are working to keep deer
off the roadway, while allowing them to get to the other side safely
with specially designed crossing structures.
BACKGROUND
Mule deer populations are stable or declining in many of the western states and provinces. The causes for declines
are varied and can be difficult to identify, but often are habitat related. High traffic roads can reduce habitat quality
through the isolation of valuable resources. They can also be a source of direct mortality. If we can reduce highway
mortalities while maintaining or restoring quality connected habitat, populations could reverse their decline and
begin to grow.
EFFECTS OF HIGHWAYS ON MULE DEER
Highways affect mule deer in two critical ways; directly through mortality caused by vehicle strikes, and indirectly
through fragmentation of habitat that can keep mule deer from acquiring needed resources and reduce genetic
interchange. Fenced highways fragment the habitat, disrupt seasonal and daily movements, and can isolate breeding
populations. Wide, unfenced highways with large traffic volumes can also be obstacles to deer movement. These
disruptions to habitat and travel often decrease the survival or reproduction rates of individuals, which can lead to
population declines.
To be effective, wildlife and highway managers have to solve 2 fundamental problems. First, keep deer away from
vehicles, and second, ensure that the highway remains permeable enough that the natural daily and seasonal
movements of deer are not significantly impacted by the highway. Exclusionary fencing, used together with proper
crossing structures, are the preferred and most successful methods to reduce vehicle-caused mortality and allow deer
populations to move freely through the landscape.
COST OF DEER-VEHICLE COLLISIONS TO SOCIETY
Researchers have identified that each deer-vehicle collision costs society over $8,000. These costs include vehicle
damage, insurance claims, medical bills, removal of carcasses, and recreational value of deer. These costs help
justify mitigation measures such as wildlife crossings and fencing by illustrating the long-term cost-benefit of such
structures.
CROSSING STRUCTURES
There are 2 basic types of wildlife crossing structures: overpasses and underpasses. Overpasses facilitate wildlife
passage above a roadway, while underpasses are structures that allow wildlife to cross underneath a roadway.
AZGFD - George Andrejko
HIGHWAY EFFECTS ON MULE DEER MOVEMENT AND SURVIVAL
Fact Sheet #3
Overpasses can be thought of as bridges which cross over a road.
They contain a continuous strip of vegetation which connects the
natural landscape on one side of the road to the other side. There
are less than 100 overpasses worldwide. The oldest overpass in
North America was built for mule deer over I-15 in Utah. The best
known and most studied overpasses occur in Banff National Park
in Canada.
Wayne Wakkinen
HIGHWAY EFFECTS ON MULE DEER MOVEMENT AND SURVIVAL
Underpasses allow wildlife to pass under the road. There are
primarily 2 types: bridges and culverts. Single-span bridges rest
only on abutments at each end of the bridge, and multi-span
bridges have intermediate support columns between abutments.
Culverts pass under the road surface, and are entirely surrounded
by the roadbed. Culverts come in a variety of sizes and shapes,
including square, rectangular, elliptical, and cylindrical, and are
commonly made of concrete or steel. Both deer and elk prefer to
use overpasses or large, open underpasses.
FACTORS AFFECTING MULE DEER CROSSING SUCCESS
The size, type, and location of mule deer crossing structures are important attributes to their success because not
all species or even all populations use these structures in the same way. Researchers have learned that deer prefer
wildlife crossings that are open and spacious because the openness allows a better view of potential predators. The
most important roadway attribute affecting use of crossing structures by large ungulates is road width. Wider paved
roads require larger crossing structures to effectively pass deer. The location of mule deer crossing structures is the
most important factor in their success. Knowledge of movement patterns of mule deer is an important prerequisite
to the placement of these structures. Deer tend to use the same routes year after year, so the most effective crossing
structures are those placed where deer traditionally cross roads.
• Natural draws or ridge tops which help guide an animal to a crossing
• Areas covered with vegetation to help an animal feel safe, but that
also allow some visual openness to look for ambush predators
(i.e., mountain lion)
• Distant from human use
• Devoid of, or having minimal, snow cover
• Location of food and water sources
• Land ownership for long-term conservation
• Large habitat blocks on both sides of the highway
FENCING - Fencing is an integral part in reducing deer mortality on
highways. Fencing keeps deer off the road and away from vehicles, and
it funnels animals into specially designed crossing structures. Without fencing, mule deer will not use crossing
structures. Fencing must receive regular maintenance in order to retain its effectiveness in keeping wildlife off the
highway. Fences must also be built with appropriate escape gates or jump outs so animals that end up on the wrong
side of the fence can escape. Long stretches of fencing without crossing structures will reduce vehicle strikes, but are
not recommended because they fragment the habitat and disrupt animal movement.
More information on mule deer can be found at www.muledeerworkinggroup.com
A product of the Mule Deer Working Group - Sponsored by the Western Association of Fish & Wildlife Agencies - Approved July 2013
Produced with support from the Mule Deer Foundation (www.muledeer.org)
Patricia Cramer
Locations of movement corridors can be identified through movement studies, roadkill, data or expert-based
knowledge. Once movement corridors are identified, biologists and engineers should use landscape features when
placing wildlife crossings, including
RELATIONSHIPS AMONG MULE DEER AND THEIR PREDATORS
Fact Sheet #1
OVERVIEW
Numbers of elk have increased and mule deer (hereafter deer)
populations have declined in many parts of western North
America during the last several decades. These trends have led
many people to question potential competition between the
species. However, simply observing that elk and deer eat the
same forage does not demonstrate competition. Impacts must
take the form of decreased survival or productivity leading to
decreased population growth to be important in population
dynamics.
AZGFD - George Andrejko
COMPETITION BETWEEN MULE DEER AND ELK
Fact Sheet #4
FACTORS INFLUENCING COMPETITION
Competition can occur when a species uses a resource (like forage), making it unavailable to another species (exploitative) or when social interactions keep another species from effectively obtaining some resource (interference). Deer
and elk have developed a number of adaptations which influence their capability to compete with each other when
resources are limited.
ENERGETICS AND DIET
Deer and elk generally select habitats and behave in a manner that allows them to maximize and conserve energy. In
summer deer expend more energy than elk to stay cool because deer pant to dissipate heat whereas elk sweat extensively, a process that requires less relative energetic cost. In winter, moving in deep snow is more difficult for deer than
elk. Thus, elk can often use more diverse areas and resources than deer in summer and winter.
Elk are more likely to have a competitive foraging advantage over deer because
1) Deer have a smaller relative stomach volume, so deer need higher quality, more digestible forage, whereas elk
can use lower-quality forage, but need large amounts,
2) Elk have a greater vertical reach than deer, allowing them to forage on taller plants,
3) Elk can take advantage of preferred deer foods such as shrubs in winter, but deer rarely make extensive use of
common elk forages (like grasses),
4) Deer rely on more rapid digestion than do elk, so plant compounds that slow digestion may be more detrimental
to deer, and
5) Elk usually eat a greater variety of plant species than deer and are less selective in which plant parts they
consume.
Severe winter weather typically contributes to lower mule deer survival and productivity than for elk. Thus, deer display more pronounced population fluctuations compared to elk. However, deer exhibit higher reproductive potential
than elk, breeding more frequently as yearlings and often producing twins. Therefore, deer populations can rebound
more quickly after declines if habitat conditions and other factors are favorable.
HABITAT AND HUMAN ACTIVITIES
Habitat changes caused by actions of European settlers led to increased shrub density in areas previously dominated by grasses or dense forests, which produced high quality deer habitat and high deer numbers during the early to
IDFG - Paul Atwood
COMPETITION BETWEEN MULE DEER AND ELK
mid-1900s. Nevertheless, these early and mid-successional habitats that favored mule deer gradually declined in value
during the mid- to later 20th century or were replaced by forests or grasslands. Most of these changes tend to favor elk
over deer. Evidence from research on the Starkey Experimental Forest and Range in Oregon indicates deer avoid elk
and may therefore be excluded from some habitats when elk are present. Such interference competition could reduce
deer productivity (such as cases were does are displaced from high quality habitat used for fawning and fawn-rearing).
Human activity can have greater negative influence on deer in several circumstances:
1) Development and encroachment is generally more severe for deer because most development typically occurs
on lower elevation winter range and elk tend to winter at higher elevations;
2) For the same reason (as well as greater avoidance of traffic by elk), deer mortality on highways and railways
often far exceeds that of elk;
3) Winter feeding may exacerbate competition if higher concentrations of elk reduce forage or range condition; and
4) Human activity, including hunting, may cause elk to shift habitat use to areas of greater cover (shrub or forest)
and consume forage normally used by deer.
Both deer and elk may avoid pastures stocked with cattle, and deer may shift away from preferred habitats when cattle
grazing is moderate to heavy, particularly in the absence of elk. If livestock grazing displaces both deer and elk, less
habitat may be available, and competition between deer and elk could occur or increase.
CONCLUSIONS AND RECOMMENDATIONS
A broad statement that elk are responsible for mule deer declines is certainly not accurate. Several important mule
deer populations have declined even without elk being present. Other deer populations have grown and responded
well in conjunction with growing elk herds.
If elk are having a negative influence on deer populations, what can managers do to positively influence deer? Acknowledgment that not every piece of land may be able to support large populations of both species is an important
first step.
Some options for management include
1) Select some areas (at landscape levels) where management will favor mule deer and others where elk will be
favored,
2) Implement actions that return habitats to early successional stages with a lot of shrubs (such as prescribed fire
and timber harvest to reduce stand density, and seeding with favored mule deer forages),
3) In areas where elk winter ranges do not overlap deer, improve habitat for elk (enhance grass-dominated ranges
and reduce human activity),
4) Consider structuring elk hunting seasons to reduce potential impacts on deer, and
5) Consider reducing elk populations in selected areas (must include adequate monitoring of deer population
responses).
Finally, we must recognize that it took several decades of change to end up with degraded mule deer habitat and it
may well take decades to reverse this trend. All stakeholders must remain committed to a long-term adaptive management process if we are to reverse mule deer habitat trends of the magnitude we have experienced.
More information on mule deer can be found at www.muledeerworkinggroup.com
A product of the Mule Deer Working Group - Sponsored by the Western Association of Fish & Wildlife Agencies - Approved July 2013
Produced with support from the Mule Deer Foundation (www.muledeer.org)
RELATIONSHIPS AMONG MULE DEER AND THEIR PREDATORS
Fact Sheet #1
CARRYING CAPACITY - HOW MANY DEER CAN WE HAVE?
Fact Sheet #5
BACKGROUND
The land can only support a limited number of animals
before resources are depleted. Exceeding the land’s
resources results in poor animal body condition, fewer
fawns surviving to adulthood, and eventual damage
to the habitat. Therefore, understanding relationships
between mule deer and their habitats is necessary for
understanding deer themselves.
Most livestock operators understand the concept of
carrying capacity, which is the number of animals a
given amount of land can support sustainably. A pasture
or allotment can only feed a certain number of cattle in a
given year.
This concept also applies to wildlife. As animal density increases, or habitat quality or quantity decreases, deer
productivity and survival decline. The number of deer the land can sustain over the long term ultimately is
determined by the available habitat – food, water, and space. It is important to note that carrying capacity varies
seasonally, annually, and over time in accordance with changing habitat conditions.
THE INFLUENCE OF HABITAT
Mule deer habitat is affected by a combination of many factors, including fire suppression, oil-gas-mineral mining,
habitat fragmentation, spread of invasive plants, drought, competition between species, livestock management, and
other human factors such as urban development. Many of these changes to deer habitat reduce carrying capacity.
Mule deer occur in a diverse set of environmental and climatic conditions and limiting factors to population size vary
by habitat type. In much of their southern ranges, desert-like conditions prevail and precipitation is a key limiting
factor to populations. In other climates, mule deer can be limited by winter range and snow accumulation. Mule deer
thrive in young habitats, where forbs, grasses, and shrubs dominate the landscape. As forests age, less nutrients, light,
and water are available for the forage plants deer prefer, so forage quality declines. Although the acres of habitat may
not change, mule deer carrying capacity can vary significantly.
Quality habitat increases fawn survival. This results in a productive population and more buck hunting opportunity
because half of the fawns that survive to adulthood are bucks.
MONITORING
Because carrying capacity is always changing, it is difficult and expensive to measure over the entire landscape.
Therefore, we monitor deer population performance in several ways that tell us whether the size of the population is
appropriate for the amount and quality of available forage.
CARRYING CAPACITY - HOW MANY DEER CAN WE HAVE?
Key indicators include density, survival, body condition (fat deposition), reproduction, and recruitment (juvenile
survival to adulthood). In locally dense populations or high population years, it also is important to measure habitat
conditions to prevent over-grazing of preferred forage plants.
THE SCIENCE OF HABITAT LIMITATION
Several studies have shown that deer populations are limited by available habitat.
• In Colorado, experimentally increasing deer nutrition increased fawn and adult survival by reducing
predation and malnutrition rates.
• Another Colorado study showed that fawns wintering in habitat treatments that removed trees and weeds had
significantly higher survival than fawns in untreated areas.
• In the Desert Southwest, research documented low precipitation is directly related to poor body condition and
high mortality of adult deer due to malnutrition.
• Several studies and experiments have demonstrated that poor body condition also reduces pregnancy rates
and fawn survival.
MANAGEMENT IMPLICATIONS
Managers use all of this information to align deer populations with the available habitat. These studies emphasize
the importance of setting realistic population objectives to help prevent large-scale die-offs during drought or severe
winters. Managers seek to achieve population objectives in several important ways:
• If a population is above its population objective, doe harvest can reduce the population to levels appropriate
for the habitat.
• In winter-stressed herds, travel and recreation closures are used to reduce disturbance and increase survival.
• Managers can increase habitat quality through the use of prescribed fire or mechanical treatments to
reduce tree cover and by making sure grazing levels are appropriate.
• Habitat conservation is critical for the future of mule deer.
More information on mule deer can be found at www.muledeerworkinggroup.com
A product of the Mule Deer Working Group - Sponsored by the Western Association of Fish & Wildlife Agencies - Approved July 2013
Produced with support from the Mule Deer Foundation (www.muledeer.org)
RELATIONSHIPS AMONG MULE DEER AND THEIR PREDATORS
Fact Sheet #1
UNDERSTANDING MULE DEER AND ANTLER POINT RESTRICTIONS
Fact Sheet #6
Antler restrictions are harvest restrictions that limit buck
harvest to animals that meet specific antler criteria. The
most common type of antler restriction is a point restriction.
Antler point restrictions have been used as a harvest strategy
with the hope they will increase the number of large-antlered
bucks in a mule deer population. Experience of many states
and provinces with antler point restrictions suggest this
harvest strategy has very limited potential to produce more
trophy bucks and could result in other unintended challenges.
BACKGROUND
Increasing the number of big-antlered bucks is typically the
basis for hunter demands to implement antler point restrictions.
The idea seems straightforward and promising; if we just don’t
allow hunters to harvest young bucks, they will grow older and
bigger and be available for harvest later. Most western states
and provinces have, at one point in time, employed some type
of antler point restriction attempting to increase the number of
“trophy” bucks in their herds.
THE GOOD
• Decreases hunter pressure and total buck harvest by discouraging some hunters who do not want to be
restricted to a particular antler-sized buck. This can be beneficial when harvest is heavy in relation to the
number of available bucks, but not heavy enough to warrant changing to limited quota seasons.
• In some cases, antler point restrictions have increased the proportion of bucks in the population, but this
effect may not be long-lasting.
• In remote areas with limited access, antler point restrictions have been used in combination with general
seasons to maintain hunter opportunity.
THE BAD
• Antler point restrictions focus all the hunting pressure on the oldest age classes of bucks, gradually decrease the
average age of the buck segment of the population, and make it more difficult for bucks to reach the older age
classes due to the displaced harvest pressure.
• Antler point restrictions have been shown to reduce the number of trophy bucks over time by protecting only the
smaller-antlered young bucks.
• Antler point restrictions do not increase fawn production or population size. Even in herds with very low
buck:doe ratios (<10:100), pregnancy rates are well over 90%. Large increases in buck ratios result in relatively
few, or no, additional fawns.
Shawn Gray
UNDERSTANDING MULE DEER AND ANTLER POINT RESTRICTIONS
Antler point restrictions often fail to provide the intended benefit as this large two-point mule deer buck
is not typically what hunters aspire to create or maintain with antler point restrictions.
THE UGLY
• Antler point restrictions dramatically reduce hunter participation, harvest success, and total harvest.
• Antler point restrictions increase the number of deer shot and illegally left in the field; this can be significant,
and has been documented in Wyoming, Colorado, Utah, Oregon, Nevada, and Montana.
• Antler point restrictions can cheapen the value of young bucks by changing the threshold for success from
“a buck” to a quest where only a big buck will do.
• Antler point restrictions may discourage hunters (especially beginning and young hunters) by increasing the
difficulty of locating and identifying legal deer.
CONCLUSIONS
After decades of use and many evaluations reporting disappointing results, most western states and provinces
have discontinued statewide antler point restrictions. The two main reasons for abandoning widespread antler
point restrictions are (1) unacceptable accidental-illegal kill, and (2) harvest mortality was increased (focused) on
the very age classes they intended to promote. Available data and experience suggest antler point restrictions result
in no long-term increase in either the proportion or number of mature bucks, or the total deer population. A few
jurisdictions still have limited areas with antler point restrictions, due to hunter preference. The use of antler point
restrictions in a combined strategy with general seasons is used in at least one case to maximize hunting opportunity.
There are additional reasons why the widespread use of antler point restrictions has not been successful. Research
has shown buck fawns born to does in poor body condition have difficulty outgrowing the effects of poor body
condition at birth, and may never reach their genetic potential for antler growth. Regulations protecting these
bucks from harvest are counterproductive to the intended benefit.
Most western states and provinces have concluded that sustainable improvements in buck:doe ratios and the number
of mature bucks can only be realized by reducing harvest through 1) a limited-quota license system that decreases
overall total buck harvest while allowing some level of doe harvest, or 2) setting a very short hunting season in early
fall when more mature bucks are less vulnerable.
It has been suggested while antler point restrictions may increase the proportion of bucks in certain populations with
low buck:doe ratios, there is no evidence they substantially increase the total number of adult (mature) bucks.
More information on mule deer can be found at www.muledeerworkinggroup.com
A product of the Mule Deer Working Group - Sponsored by the Western Association of Fish & Wildlife Agencies - Approved July 2013
Produced with support from the Mule Deer Foundation (www.muledeer.org)