relationships among mule deer and their predators · relationships among mule deer and their...

RELATIONSHIPS AMONG MULE DEER AND THEIR PREDATORSFact Sheet #1

OVERVIEWRelationships between predator and prey abundance are complex and not easily described. Under certain conditions, predators may in�uence �uctuations in mule deer populations and a�ect the goals that managers set for a speci�c 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 e�ective 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 e�ect on mule deer populations. However, many factors interact to in�uence 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 in�uence 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 ine�cient and cost prohibitive. �erefore, predator control should only be instituted when circumstances indicate a high likelihood of management success, and where speci�c and measurable objectives can be applied and carefully monitored.

THE INFLUENCE OF PREDATORS�e in�uence 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.

When mule deer populations are close to carrying capacity, predation tends to have less in�uence 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 e�ects 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 in�uence predator abundance (e.g., increased coyote numbers may result in decreased bobcat numbers). In short, the relationships between predator and prey are complex, di�cult to isolate and characterize, and rarely result in simple management solutions.

USING SCIENCE TO GUIDE MANAGEMENTIn reviewing scienti�c research on predator control, there were similarities in cases where predator control was e�ective at improving deer populations. In general, predator control has been e�ective when: 1) Predation was identi�ed as a limiting factor, 2) Predator control was implemented when deer populations were below habitat carrying capacity, 3) Control e�orts reduced predator populations su�ciently across the landscape to yield results (e.g., expected to be about 70% of a local coyote population), 4) Control e�orts were timed to be most e�ective (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 identi�es: 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 e�ort, f. Timing, method, and budget for predation management e�orts, 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.

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.


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A product of the Mule Deer Working Group - Sponsored by the Western Association of Fish & Wildlife Agencies - Approved July 2013“Produced with support from Federal Premium Ammunition and the Mule Deer Foundation (www.muledeer.org)”

More information on mule deer can be found at www.muledeerworkinggroup.com

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 di�ering 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 bene�t mule deer populations is only e�ective under a few speci�c conditions.

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RELATIONSHIPS AMONG MULE DEER AND THEIR PREDATORS


UNDERSTANDING MULE DEER AND WINTER FEEDINGFact Sheet #2

BACKGROUND - Supplemental winter-feeding programs, despite broad social appeal and acceptance, are expensive, can negatively a�ect 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 bene�ts 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. Speci�c types of bacteria are required for speci�c types of food, therefore the type of food required for winter feeding of mule deer is highly limited, very speci�c, and must be properly formulated. Because the digestive system can’t adapt quickly enough, supplementally fed mule deer may die with full stomachs. �is 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 a�ected by winter-feeding e�orts. 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 o�spring. As each generation becomes more reliant on arti�cial 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 arti�cially high animal densities at feeding sites. �ese high densities of animals provide ideal opportunities for the transmission of diseases and parasites. Winter feeding in areas highly populated by humans may create signi�cant liability issues in terms of attracting predatory animals such as mountain lions and domestic dogs.

COMPETITION - Mule deer compete �ercely 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.

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 o�en fail to signi�cantly 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 o�en providing food sources that may ultimately kill deer. Uncoordinated or casual feeding e�orts result in dozens of di�erent foods being fed, while deer migratory habits, foraging behavior, and fear of humans are also negatively a�ected. Feeding can attract deer into landscaped yards and high tra�c areas, causing damage to gardens and increasing vehicle accidents. People who feed deer o�en ignore the real issue of availability and condition of natural habitats. �ey 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 bene�t, o�en negated by undesirable, even catastrophic, behavioral and biological e�ects. 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 bene�cial. �is is o�en 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 bene�ts of winter feeding realized.

Winter feeding of mule deer creates arti�cially high concentrations of animals, leading to increased risks, including disease transmission and predation.

Winter-fed mule deer o�en die with full stomachs due to their inability to adapt to

rapid changes in type and abundance of feed.

Starvation of wild animals is part of nature. Virtually all wild animal populations experience signi�cant and dramatic population �uctuations. 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.


UNDERSTANDING MULE DEER AND WINTER FEEDING



HIGHWAY EFFECTS ON MULE DEER MOVEMENT AND SURVIVALFact Sheet #3


BACKGROUNDMule deer populations are stable or declining in many of the western states and provinces. �e causes for declines are varied and can be di�cult to identify, but o�en are habitat related. High tra�c roads can reduce habitat quality through the isolation of valuable resources. �ey 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 a�ect 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 tra�c volumes can also be obstacles to deer movement. �ese disruptions to habitat and travel o�en decrease the survival or reproduction rates of individuals, which can lead to population declines.

To be e�ective, 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 signi�cantly 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 SOCIETYResearchers have identi�ed that each deer-vehicle collision costs society over $8,000. �ese costs include vehicle damage, insurance claims, medical bills, removal of carcasses, and recreational value of deer. �ese costs help justify mitigation measures such as wildlife crossings and fencing by illustrating the long-term cost-bene�t of such structures.

CROSSING STRUCTURES�ere 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.

Overpasses can be thought of as bridges which cross over a road. �ey contain a continuous strip of vegetation which connects the natural landscape on one side of the road to the other side. �ere are less than 100 overpasses worldwide. �e oldest overpass in North America was built for mule deer over I-15 in Utah. �e best known and most studied overpasses occur in Ban� National Park in Canada.

Underpasses allow wildlife to pass under the road. �ere 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�e 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. �e most important roadway attribute a�ecting use of crossing structures by large ungulates is road width. Wider paved roads require larger crossing structures to e�ectively pass deer. �e 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 a�er year, so the most e�ective crossing structures are those placed where deer traditionally cross roads.

Locations of movement corridors can be identi�ed through movement studies, roadkill, data or expert-based knowledge. Once movement corridors are identi�ed, biologists and engineers should use landscape features when placing wildlife crossings, including

OVERVIEWMule deer need open landscapes to make a living. �ey 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 provin-cial wildlife and transportation agencies are working to keep deer o� the roadway, while allowing them to get to the other side safely with specially designed crossing structures.

FENCING - Fencing is an integral part in reducing deer mortality on highways. Fencing keeps deer o� 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 e�ectiveness in keeping wildlife o� 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.

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HIGHWAY EFFECTS ON MULE DEER MOVEMENT AND SURVIVAL

• 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

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COMPETITION BETWEEN MULE DEER AND ELKFact Sheet #4

A product of the Mule Deer Working Group - Sponsored by the Western Association of Fish & Wildlife Agencies - Approved July 2013Produced with support from the Mule Deer Foundation (www.muledeer.org)


FACTORS INFLUENCING COMPETITIONCompetition can occur when a species uses a resource (like forage), making it unavailable to another species (exploit-ative) or when social interactions keep another species from e�ectively obtaining some resource (interference). Deer and elk have developed a number of adaptations which in�uence their capability to compete with each other when resources are limited.

ENERGETICS AND DIETDeer 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 exten-sively, a process that requires less relative energetic cost. In winter, moving in deep snow is more di�cult for deer than elk. �us, elk can o�en 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. �us, deer dis-play more pronounced population �uctuations compared to elk. However, deer exhibit higher reproductive potential than elk, breeding more frequently as yearlings and o�en producing twins. �erefore, deer populations can rebound more quickly a�er 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 dominat-ed by grasses or dense forests, which produced high quality deer habitat and high deer numbers during the early to

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-rear-ing).

Human activity can have greater negative in�uence 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 tra�c by elk), deer mortality on highways and railways o�en 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 shi� 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 shi� 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 RECOMMENDATIONSA 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 in�uence on deer populations, what can managers do to positively in�uence deer? Ac-knowledgment that not every piece of land may be able to support large populations of both species is an important �rst 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 �re 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 man-agement process if we are to reverse mule deer habitat trends of the magnitude we have experienced.

OVERVIEWNumbers of elk have increased and mule deer (herea�er deer) populations have declined in many parts of western North America during the last several decades. �ese 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.

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COMPETITION BETWEEN MULE DEER AND ELK


CARRYING CAPACITY - HOW MANY DEER CAN WE HAVE?Fact Sheet #5



BACKGROUND �e 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. �erefore, 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.

�is concept also applies to wildlife. As animal density increases, or habitat quality or quantity decreases, deer productivity and survival decline. �e 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 HABITATMule deer habitat is a�ected by a combination of many factors, including �re 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 signi�cantly.

Quality habitat increases fawn survival. �is results in a productive population and more buck hunting opportunity because half of the fawns that survive to adulthood are bucks.

MONITORINGBecause carrying capacity is always changing, it is di�cult and expensive to measure over the entire landscape. �erefore, 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.

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 LIMITATIONSeveral 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 signi�cantly 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 IMPLICATIONSManagers use all of this information to align deer populations with the available habitat. �ese studies emphasize the importance of setting realistic population objectives to help prevent large-scale die-o�s 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 �re 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.

CARRYING CAPACITY - HOW MANY DEER CAN WE HAVE?


UNDERSTANDING MULE DEER AND ANTLER POINT RESTRICTIONSFact Sheet #6

BACKGROUND Increasing the number of big-antlered bucks is typically the basis for hunter demands to implement antler point restrictions. �e 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. �is can be bene�cial 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 e�ect 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 di�cult 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.

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 le� in the �eld; this can be signi�cant, 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 di�culty of locating and identifying legal deer.

CONCLUSIONSA�er decades of use and many evaluations reporting disappointing results, most western states and provinces have discontinued statewide antler point restrictions. �e 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. �e use of antler point restrictions in a combined strategy with general seasons is used in at least one case to maximize hunting opportunity.

�ere 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 di�culty outgrowing the e�ects 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 bene�t.

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.

Antler point restrictions o�en fail to provide the intended bene�t as this large two-point mule deer buck is not typically what hunters aspire to create or maintain with antler point restrictions.



Antler restrictions are harvest restrictions that limit buck harvest to animals that meet speci�c antler criteria. �e 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.

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UNDERSTANDING MULE DEER AND ANTLER POINT RESTRICTIONS



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Background In the early days of wildlife management, protection of female deer and their fawns was fundamental in helping mule deer populations grow throughout most of their range. Mule deer numbers eventually rebounded and antlerless harvest was needed to address declining forage supplies from overuse or agriculture damage. �is management tool has been controversial over the years and to this day doe harvest is less socially acceptable than buck harvest with many hunters. However, antlerless harvest can be used to stabilize or decrease mule deer populations depending on the level of harvest and natural mortality occurring within a population.

Any source of mortality can be characterized as being somewhere along the continuum from mostly compensatory to mostly additive mortality. Compensatory hunting mortality is harvest that mostly replaces mortality that would naturally occur in a population. When populations exceed the habitat’s carrying capacity, resources become limited, habitat degradation occurs, and animals have poor body condition which decreases adult survival and reproduction. Under these conditions, some of the animals removed by hunting are in excess of the habitat’s ability to support them. Although sources of mortality are rarely completely compensatory, most of these animals removed would have died of other causes (like disease and starvation). In populations near carrying capacity, female harvest can result in higher fawn production and survival because remaining deer are in better condition and this can also compensate for harvest mortality.

Additive mortality occurs when deaths are not compensated for by increased reproduction or a reduction in other causes of mortality, it simply results in less deer. �is occurs most o�en when populations are not over carrying capacity and the habitat can support more deer. Harvest mortality must be mostly additive to decrease a given population. �erefore, to reduce a population at or above carrying capacity, doe harvest needs to be set at a level high enough to overcome compensation of mortality.

Using Science to Guide Management�e impact of antlerless harvest on population trend depends on the proportion of adult does harvested and recruitment of fawns into the population. If hunting mortality is partially compensated for by higher fawn recruitment and/or less animals dying later of something else, then doe harvest may need to be increased to reduce the population. �e natural mortality rate tends to decrease as harvest increases (compensation) to a certain point, but above that level all other mortality becomes additive.

Studies have shown that environmental factors such as drought, deep snow, and extreme temperatures have the greatest impact on fawn survival. However, these same environmental conditions may have less e�ect on adult doe survival. Harvest of fawns is more compensatory than other age classes because their survival is naturally much lower than adult deer. Hunting mortality of fawns during an antlerless hunting season is typically much less than adult females because of hunter selectivity.

Because adult does have relatively low rates of natural mortality, harvest of this segment of the population has a greater chance of being additive. Antlerless harvests must be adjusted in relation to adult female survival and fawn recruitment in each population because signi�cant harvest of adult females in areas with low fawn recruitment will result in a more substantial population decline. In fact, in populations with chronically low fawn recruitment and an ample supply of habitat, doe harvest is frequently not necessary.

Not only does the health of adult females have an impact on fawn recruitment, but their age plays a role as well. Populations maintained at densities below the carrying capacity of the habitat through antlerless harvest may have increased fawn recruitment resulting in a younger female age structure. Research has shown that recruitment of fawns is lower in does less than 2 years of age. If harvest is intense enough to signi�cantly decrease the average age of the doe population, fawn recruitment may be reduced.

Putting it into Practice�e additive portion of adult female harvest has the greatest potential to in�uence population size. However, extensive antlerless harvest does not guarantee that populations will decline because mortality can be completely replaced by fawn recruitment. Population trajectory depends on the balance between additions to (fawn recruitment) and subtractions from (mortality) the population. Managers constantly use adaptive management principles to determine the appropriate level of

female removal needed to properly adjust the population level.

Concern has been raised among sportsmen regarding perceived higher mortality of orphaned fawns associated with antlerless harvest. Research indicates that fall doe hunts have no detrimental e�ects on survival or development of orphaned fawns at that time. In fact, most antlerless hunting seasons are structured to occur well a�er the fawns are weaned and self-su�cient. Removing an adult female can actually provide more habitat for the remaining deer, including the current year’s fawns.

Antlerless harvest is an important tool to help managers control deer population levels. In addition, doe hunting serves as a valuable opportunity to get hunters a�eld, especially youth. �ere are numerous techniques accepted and used by managers that yield reliable data for establishing harvest rates and monitoring mule deer abundance. �ese data provide essential information to determine if doe harvest is necessary and to select the appropriate harvest rate for a particular herd or management unit.

Antlerless harvest of mule deer can be an e�ective tool for managing population levels. Harvesting

females can help maintain sustainable populations and prevent large-scale die-o�s or over-utilization of habitat. State and Provincial agencies collect a variety of biological data to help formulate antlerless harvest strategies and quotas to manage mule deer populations and their habitats.



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Because adult does have relatively low rates of natural mortality, harvest of this segment of the population has a greater chance of being additive. Antlerless harvests must be adjusted in relation to adult female survival and fawn recruitment in each population because signi�cant harvest of adult females in areas with low fawn recruitment will result in a more substantial population decline. In fact, in populations with chronically low fawn recruitment and an ample supply of habitat, doe harvest is frequently not necessary.

Not only does the health of adult females have an impact on fawn recruitment, but their age plays a role as well. Populations maintained at densities below the carrying capacity of the habitat through antlerless harvest may have increased fawn recruitment resulting in a younger female age structure. Research has shown that recruitment of fawns is lower in does less than 2 years of age. If harvest is intense enough to signi�cantly decrease the average age of the doe population, fawn recruitment may be reduced.

Putting it into Practice�e additive portion of adult female harvest has the greatest potential to in�uence population size. However, extensive antlerless harvest does not guarantee that populations will decline because mortality can be completely replaced by fawn recruitment. Population trajectory depends on the balance between additions to (fawn recruitment) and subtractions from (mortality) the population. Managers constantly use adaptive management principles to determine the appropriate level of

female removal needed to properly adjust the population level.

Concern has been raised among sportsmen regarding perceived higher mortality of orphaned fawns associated with antlerless harvest. Research indicates that fall doe hunts have no detrimental e�ects on survival or development of orphaned fawns at that time. In fact, most antlerless hunting seasons are structured to occur well a�er the fawns are weaned and self-su�cient. Removing an adult female can actually provide more habitat for the remaining deer, including the current year’s fawns.

Antlerless harvest is an important tool to help managers control deer population levels. In addition, doe hunting serves as a valuable opportunity to get hunters a�eld, especially youth. �ere are numerous techniques accepted and used by managers that yield reliable data for establishing harvest rates and monitoring mule deer abundance. �ese data provide essential information to determine if doe harvest is necessary and to select the appropriate harvest rate for a particular herd or management unit.

ANTLERLESS MULE DEER HARVESTFact Sheet #7



When combined with e�ective population monitoring, regulated hunting is a valuable tool for wildlife managers to in�uence mule deer population size and structure. When mule deer recruitment is high and populations exceed what habitats can reasonably support, harvest tends to replace other forms of mortality with no e�ect on populations. In situations where recruitment is lower than overall mortality, additional harvest, especially females, is less likely to replace other morality (it becomes additive) and populations can decline. Illegal harvest (Poaching), in addition to prescribed legal harvest can be additive and limit population growth.

BACKGROUNDObtaining estimates of illegal harvest rates is notoriously di�cult; poachers by their very nature are not outwardly obvious. Illegal activities will o�en occur during legitimate, established hunting seasons. Researchers have estimated that as few as 1–2% of wildlife law violations ever come to the attention of law enforcement authorities.

Reasons for illegal harvest vary widely. Commonly-cited reasons include trophy poaching, commercial gain, household consumption (subsistence), recreational satisfactions, killing just to shoot something, protection of self and property, poaching to rebel against regulation, traditional rights of use, disagreement with speci�c regulations, and the simple challenge of eluding law enforcement o�cers.

IMPACTS OF POACHING ON MULE DEER POPULATIONSIllegal harvest can have a variety of impacts on deer populations, depending on the extent of illegal activities. In Colorado, long-term monitoring of radio collared deer indicates illegal harvest is not a signi�cant factor, ranging from 0.4%–1.5% of doe mortalities and 1.5% – 1.7% of buck mortalities. However, in a study currently being summarized in Oregon, illegal harvest appears to be much higher than reported elsewhere. Managers believe illegal take of females is additive and contributing to the declining population trend in that study area. �ey observed no seasonal or spatial patterns of when and where deer were poached. Illegal removal of too many older bucks for trophy reasons can skew buck:doe ratios and potentially reduce the overall age structure of bucks. Most importantly, illegal removal of these mature bucks from the huntable population can reduce future lawful hunting opportunities.

OVERVIEWMule deer populations are stable or declining in many western states and provinces. Causes are varied and can be di�cult to identify. In simple terms, populations grow when the number of o�spring that reach adult-hood (recruitment) exceeds the number of adults that die from all causes. When habitat is not the primary limiting factor, balancing mortality with recruitment can stabilize a population or allow it to grow.

ACTIONS TO REDUCE POACHING ON MULE DEERLaw enforcement authorities in mule deer country use a variety of actions designed to deter and reduce poaching of mule deer.

• Simpli�ed regulations may reduce unintended or accidental violation of deer hunting laws.• Increasing penalties and �nes can serve as a deterrent to casual or opportunistic poachers. However, costs of some trophy hunting opportunities, such as special auction tags, may indicate penalty values need to be extremely high to have an e�ect on some individuals.• Increased enforcement activities, such as saturation patrols, and decoy operations (use of mounted game animals as bait for poachers) tend to reduce poaching activities. Enforcement actions are expensive, and maintaining a sustained presence is important. However, e�ectiveness declines as law enforcement activities are reduced; a concern as enforcement resources are a�ected by declining budgets.• Covert or undercover operations can e�ectively target established or commercial poaching operations. However, these projects might require much time (up to several years) to secure su�cient evidence, during which the resource may continue to su�er.• Many court systems in mule deer country have extraordinarily high case loads and wildlife poaching cases may not compete with more serious crimes against people or society. Educating court systems and prosecutors about the value mule deer represent to an area, and potential loss due to the� of this public resource through poaching, may increase prosecution rates in poaching-related cases. Identifying the value of lawful harvest, hunters, and hunter expenditures will reinforce this message.• �e Interstate Wildlife Violator Compact (IWVC) is a proactive deterrent to poaching; Poachers may be suspended from hunting and �shing in all 42 member states.• Perhaps the most e�ective action is to have mule deer hunters police their own ranks. Most states and provinces in mule deer ranges have a mechanism for hunters to report violations (e.g., toll-free phone numbers). �is approach capitalizes on the ethical hunter and provides rewards, usually �nancial, for turning in poachers.

CONCLUSIONSPoaching of mule deer can be a serious issue in some local populations, and occurs due to a variety of reasons. E�ects include potentially limiting population growth, a�ecting structure of populations, and impacting hunting opportunities for lawful hunters. No single solution can completely control poaching, although many law enforcement options are available and currently being used to minimize its e�ect on mule deer populations. Hunter reporting may be the single best tool available to enforcement o�cers.

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ILLEGAL HARVEST AND MULE DEER POPULATIONSFact Sheet #8



OVERVIEWIncreased urbanization has reduced, fragmented, and in some cases, eliminated critical mule deer habitat. �ese overall changes in mule deer habitat a�ect deer populations, generally leading to declines. However, in many cases, mule deer have adapted to life in urban areas, leading to con�icts with humans. Urban areas include heavily-developed urban centers along with outlying suburban and exurban areas. Mule deer population can increase rapidly in these areas as deer take advantage of the abundant forage and water sources provided by humans as well as protection from hunting and other types of predation. Habituation to humans in close settings allows mule deer to exist at densities above what is generally seen in the wild. How urban mule deer impact people is o�en dependent on human tolerance levels, which can vary by community.

NEGATIVE IMPACTSMule deer are browsers: preferring leaves, stems, and buds of woody plants, as well as forbs (weeds). Like many other wildlife species, mule deer are opportunistic and in some cases will eat and damage ornamental plants, hedges, vegetables, �owers, and lawns. Bucks can damage shrubs and saplings by rubbing the bark with their antlers. �is damage to personal and commercial-ly-grown vegetation is not well-tolerated and can make people view mule deer as a nuisance.

Urban areas rarely allow hunting. Deer repeatedly exposed to humans without negative consequences will eventually become habituated or show little fear of humans. Habituated mule deer may become aggressive and pose a danger to human residents. �ere are reports of mule deer blu�-charging people, chasing joggers, attacking postal workers, and killing small pets. Large mule deer numbers in urban areas can also lead to more deer on roads and increase the potential for deer-vehicle collisions. Mule deer populations attract predators to urban areas, creating a possible hazard for local residents and pets. �e urban envi-ronment can have a negative impact on deer as well. Busy streets, railways, fences, parking garages, and bridges are hazards for urban deer. �ere are many reports of deer-vehicle collisions, fatal jumps from parking garages and bridges, and entanglement in fences. �e potential for disease transmission is also greater due to the high densities of deer in urban areas.

MANAGING URBAN MULE DEER ISSUES

Prohibiting Supplemental FeedingSupplemental feeding of mule deer in urban areas can greatly increase fawn production and may a�ect overall deer survival. Residents of urban areas o�en feed mule deer by hand or through a feeder because they enjoy having the deer in close proximity or feel that the deer need the supplement to survive. Inadvertent feeding also occurs such as through bird or squirrel feeders. Working with local governments to enact regulations prohibiting supplemental feeding is an important step in managing an urban deer problem. Prohibiting feeding also reduces the attractants that draw deer into the urban areas to begin with. Indi-viduals should also consider placing bird or squirrel feeders out of reach to eliminate use by deer.

Chemical Repellents and Scare DevicesSeveral techniques are available to deter urban deer. Deterrents are modestly e�ective when deer densities are relatively low and o�en lose e�ectiveness as deer abundance and problems grow. A variety of chemical deer repellents are commercially available. Repellents rarely work and require constant application, especially a�er rain or snow. Scare devices can sometimes be e�ective at deterring urban deer. Some scare devices are commercially available, but contact state wildlife o�cials for the use of noise-making scare devices such as Zon-guns (propane cannons), crackershells, and M-80s. Be sure to consult local laws before using pyrotechnic devices.

Deer-resistant plants and fencingCertain ornamental plants are unpalatable to deer and are less likely to be browsed. Using these plants in landscaping instead of more-desirable browse species can reduce deer con�icts. To determine which plants are deer-resistant and adapted to the local area contact a local nursery or state wildlife o�cial. A variety of reference books and internet resources are also available on the subject.

Fencing deer out is the most e�ective and permanent method. A wide variety of fence designs will keep problem deer out. Fences should be at least 8 feet tall with no gaps greater than 8 inches. Electric fencing also works to deter deer on a more temporary basis, such as winter browsing. A hybrid approach of installing two strands of electric wire on top of an existing fence can also be an e�ective approach. Surrounding individual plants with wire cages can prevent browsing. Also, wire mesh or pipe placed directly around tree trunks will reduce damage by bucks rubbing their ant-lers.

HuntingWildlife agencies are successfully using regulated hunting in urban areas to address urban deer issues. Carefully regulated archery hunts in restricted hunting areas can be particularly e�ective and e�cient. Some agencies have used professional shooters to kill deer with the meat donated to charitable groups. Hunting in and around urban areas requires close coordination with local governments and citizens, but where possible, it is a cost-e�ective solution.

Relocation and contraceptionSome wildlife agencies are capturing and relocating urban deer to more remote, suitable habitat on a limited basis. �is approach is labor- and cost-intensive, with uncertain e�ectiveness. Moving deer is dependent on the availability of release sites, which have to be carefully evaluated to ensure that the habitat can support more deer. Given these constraints, moving deer is unlikely to be a common solution for widespread urban deer issues in the West. Contraception is o�en proposed as a method to reduce overabundant deer populations, but it is not currently feasi-ble in free-ranging deer populations. PUBLIC OPINION AND EDUCATIONPublic input is the most important aspect of managing urban deer. �ere are a wide range of opinions regarding deer in urban areas. Some enjoy seeing deer in their backyards and tolerate the damage, while others see urban deer as a hazard and nuisance. Prudent con-sideration of all factors involved and proper public education is critically important when managing urban mule deer.

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URBAN MULE DEER ISSUESFact Sheet #9



OVERVIEWTranslocation is used by wildlife managers to restore wildlife in historical ranges, augment populations at low densities, and reduce local overpopulation issues. Capturing and moving large mammals is expensive and labor intensive as well as potentially stressful for the animals. For mule deer, data and detailed analyses on translocation e�orts are few compared to species such as elk and bighorn sheep. Recently, mule deer translocation programs in the western US have focused on reducing densities in habitats where harvesting animals is not practical or possible. In some cases translocations have been done to determine if low density populations can be increased. Wildlife agencies need to carefully consider the goals, costs, and potential outcomes and should include a monitoring component when planning to implement deer translocation programs.

BACKGROUND Translocation of big game species has been part of wildlife restoration e�orts for decades. Because of the ubiquitous distribution of mule deer, many agencies have historically not translocated mule deer. Some wildlife agencies have moved mule deer and other deer species in the past and observed low survival compared with other big game translocations. High mortality associated with capture stress or injury during transport, poor post-release survival, and high rates of predation have been observed.

�e reasons mule deer translocations had limited success in past e�orts are not fully understood due to poor or nonexistent post-release monitoring. However, casual reports and observations have indicated such outcomes as not seeing translocated deer frequently a�er the release and no noticeable increase in deer abundance in that area. To identify limiting factors associated with mule deer translocations, wildlife agencies in Utah and New Mexico have recently initiated mule deer translocations with robust post-release monitoring. A�er 1 year, survival rates were 50-70% for translocated adult deer compared to about 85% for resident adult deer. Deer were moved from high density areas where lethal removal was not socially acceptable (state parks and urban areas) and from an over-populated winter range to an area where the deer density was considered below carrying capacity. �ese investigations will help determine if mule deer translocations are a useful strategy to reduce deer density in a nonlethal manner or boost indigenous populations.

COSTS AND OTHER CONSIDERATIONSDeer translocation is an expensive and time-intensive management activity. Costs have ranged from $100 to $1,000 per animal, varying with the process, number of animals translocated, capture and handling methods, and duration of the project. Wildlife agencies have used in-house sta� or hired additional personnel to plan and coordinate capture processes, collect health samples, move deer, and monitor success.

Additional costs include radio collars, as well as vehicles and equipment. Agencies may partner with local governments, conservation groups, and other interested parties to fund and perform mule deer translocations. Communities must agree in advance on a suite of proactive practices to reduce deer/human con�icts and address the problem from many directions. �e following items are some of the most important considerations to address the societal issues when translocation e�orts are being planned: educational outreach on type of fencing and other deterrents available, deer-resistant landscaping, bylaws or regulations to prevent supplemental feeding, vehicle speed restrictions and additional signage.

Migratory populations of mule deer have high �delity to summer and winter home ranges. It is important to consider what e�ect innate migratory behavior might have on the survival of mule deer released in non-migratory herds (and vice versa). In addition, translocation must consider the high risk of introducing serious infectious diseases and parasites (such as Chronic Wasting Disease and exotic lice).

PLANNINGWhen translocation of mule deer is being considered, an important �rst step is to clearly de�ne the goals, objectives, and criteria for determining the success or failure of the project. Release sites and recipient deer populations should be evaluated well ahead of time. Sites must be historical for mule deer, provide suitable habitat with adequate forage quantity and quality, water, and cover, and have deer densities that can absorb additional animals. Releases will likely be more successful in areas with low predator abundance since released animals will take time to become familiar with the new area. Additionally, release sites should exclude areas that will create future depredation problems in agricultural or developed areas. Wildlife managers must be aware that the genetic composition of the recipient population may be a�ected by the introduction of additional animals from elsewhere. �ese changes may be bene�cial or detrimental, but should be considered. Perhaps most importantly, animals moved may also move infectious agents and a disease risk assessment should be performed. Disease and parasite exposure in both source and recipient herds should be assessed as part of that risk assessment before any translocation e�ort is undertaken, and under no circumstances should mule deer be moved from areas endemic with Chronic Wasting Disease.

ANIMAL WELFARE AND CAPTUREAnimal welfare must be considered when selecting the capture technique, method of handling and care and transport. Capture options include dropnets, clover traps, aerial or ground-based chemical immobilization, aerial net gun operations, and drive nets. Handling must be done by trained and experienced personnel with thought given to using tranquilizers or sedatives for transport, as well as providing a method of humane euthanasia should it be required. All existing animal welfare policies of the various agencies involved should be consulted. Regardless of the options used, every e�ort must be made to reduce handling time and stress on animals, and to use professionally recommended methods. Consulting an experienced wildlife veterinarian during the planning process may help with the success of the translocation.

MONITORINGTo evaluate the success of a translocation, a post-release monitoring plan must be incorporated into the program. Radio collars are the only e�ective way to estimate survival rates, cause-speci�c mortality, and track movements. Managers should plan for adequate �nances, time and personnel to properly conduct telemetry-based monitoring and subsequent data analysis. All information gathered should be shared with cooperators and the public to facilitate and inform future management decisions.

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TRANSLOCATION OF MULE DEERFact Sheet #10



OVERVIEWLong-term declines in mule deer populations have been largely attributed to changes in habitat, loss of migration corridors, and predator-prey relationships; however disease places additional pressure on waning populations. Disease and parasites in�uence overall population health, numbers, distribution, and sex and age composition. �is fact sheet discusses several important diseases and parasites of mule deer and their control, treatment, and man-agement in free-ranging populations. BACKGROUND Disease and parasites in wildlife may in�uence the individual or population. Pathogens such as bacteria, viruses, fungi or parasitic species can be transmitted among mule deer populations, to other wildlife species, domestic animals, or humans. Diseases a�ecting deer can lead to substantial economic impacts to state wildlife agen-cies and communities that depend on hunters and other wildlife enthusiasts.

Pathogens may be naturally occurring or introduced by moving wildlife. Factors a�ecting disease transmission and emergence include weather conditions, changes in pathogen virulence, deer distribution and population �uctuations, environmental changes a�ecting habitat, land-use change, increasing urban deer interactions with humans and domestic animals, deer farm-ing, and feeding and baiting of wild deer.

DISEASES IN MULE DEER Disease by itself generally does not determine mule deer abundance. However, when a disease occurs with other stressors on populations, wildlife managers must consider its signi�cance for developing management strategies. An example of this rela-tionship includes physiological stress from nutritional or mineral imbalances which may lead to increased herd susceptibility to disease. Monitoring an established disease documents its e�ect on a population, its spread, and how it relates to other factors that may be limiting populations. Rarely do disease outbreaks cause rapid or large-scale mortality in mule deer; most occur as smaller-scale die-o�s or reduce productivity.

Chronic Wasting Disease (CWD)Over the last decade, CWD has been a leading cause for concern among mule deer managers. �is infectious protein or prion causes fatal neurological disease in deer, elk and moose. Currently, CWD occurs in mule deer populations in Colorado, Wy-oming, Utah, Nebraska, North and South Dakota, New Mexico, Texas, Alberta, and Saskatchewan. Infected local populations can experience high prevalence with up to 50% of the deer carrying the deadly prion. Population declines may occur in some regions over time; however, many a�ected areas have exhibited limited or no population e�ects due to CWD.

Bacterial Diseases Bacterial diseases tend to be sporadic and rare throughout mule deer range. Rain Rot, o�en spread by ticks and �ies, results in a skin infection with thick scabs on the head and back of infected mule deer. Other bacteria occurring in the environment can enter through wounds in the skin or mouth and cause a disease called necrobacillosis, or foot rot or lumpy jaw. Infections may spread systemically or stay localized in oral or hoof lesions. Clostridium bacteria occur in the environment and the gastrointes-tinal tract of healthy mule deer. Environmental Clostridium spores can enter wounds causing gas gangrene or blackleg. When mule deer are provided supplemental feed such as grains/corn in winter, an overgrowth of intestinal bacteria can lead to severe illness and death. Mule deer are also a�icted with infectious keratoconjunctivitis, spread by �ies, which a�ects the tissues sur-rounding the eye. Less common bacterial infections of free-ranging mule deer include plague, leptospirosis, Johne’s disease, and bacterial pneumonia.

Viral Diseases Two important late summer and early fall viruses, blue-tongue virus (BTV) and epizootic hemorrhagic disease vi-ruses (EHD), are transmitted by midges and cause similar hemorrhagic disease in mule deer. Acute infection results in swelling of the head and neck, respiratory disease, or sudden death. Deer may recover with resulting lameness due to viral damaged blood vessels of the hooves. Cervid adenoviral hemorrhagic disease (AHD) is transmitted by direct contact between mule deer and can cause illness similar to BTV and EHD with symptoms of respiratory distress and internal hemorrhaging. Mule deer can also be seen with �broma tumors caused by a relatively common papillomavirus, transmitted from direct contact between deer or through biting insects. �e warty growths, though unsightly, are usually self-limiting and rarely cause death.

EctoparasitesAn exotic chewing louse of western Eurasian fallow deer occurs in mule deer populations in several western states. Infestations cause irritation and excessive grooming leading to barbering and declining body condition. Various native ticks, lice, �eas, and keds occur on mule deer but do not cause population declines. However, tick-carried blood parasites and pathogens can be carried by deer and cause disease in humans and other host animal species.

EndoparasitesNose and throat bots occur when adult female bot �ies deposit larvae in the nose of deer. �e larvae migrate to the sinuses to mature and cause the animal discomfort but are rarely more than a nuisance. Other internal parasites such as adult lungworms can cause respiratory disease in mule deer. On the eastern edge of mule deer range, the meningeal worm occurs naturally in una�ected white-tailed deer; however, mule deer develop neurological signs due to migrating worms in the brain and spinal cord. �e arterial worm, transmitted by horse �ies, occurs in the carotid arteries of una�ected mule deer, its de�nitive host. In other ungulate species it can lead to blindness and death. Many other round worms, tapeworms, �at worms and protozoan parasites can occur in mule deer.

CONTROL, TREATMENT, AND MANAGEMENT OF DISEASE IN FREE-RANGING POPULATIONSNearly all diseases occurring in mule deer are not transmissible to humans and those that can be transmitted, such as plague, are very rare. However, diseases in wildlife populations are di�cult to manage. Broad disease management goals include no management action, some level of disease control, or attempted eradication. Economic and social values must also be consid-ered with disease management alternatives. Preventing disease introduction into susceptible populations is the most e�cient and cost e�ective method of disease management. Preventative management actions in mule deer include import and trans-port restrictions, disease surveillance programs, decontamination and sanitation protocols, development of physical barriers, and restrictions on baiting and feeding. Medical treatments or population interventions are costly, di�cult, and unlikely to be e�ective.

DISEASES AND PARASITES OF MULE DEERFact Sheet #11



OVERVIEW�e ability to migrate is essential for mule deer to travel to, and access, important seasonal habitats. �rough-out the range of mule deer, migrations occur in the fall and spring as animals travel between winter and sum-mer ranges. Migration allows mule deer to avoid deep snow and other harsh conditions during winter and take advantage of high quality forage during summer. Because migration corridors serve as the critical link between summer and winter ranges, they must be unimpeded by physical barriers (e.g., game-proof fences, roads, etc.) and protected from various forms of development and human disturbance (e.g., housing and energy develop-ment).

CONSIDERATIONSRecent advances in Global Positioning System (GPS) technology have allowed wildlife researchers to obtain frequent and detailed movement data to identify migration routes of individual mule deer. Individual routes are combined to identify “migration corridors” for mule deer populations. �is detailed information has highlighted the complexities of migratory populations and the importance of conserving the key migration corridors that con-nect winter and summer ranges. For example, managers learned migrating mule deer may spend 2–4 months migrating and most of that time is spent in distinct “stopover” areas where mule deer follow the vegetation “green-up” and maximize use of nutritious vegetation. Also, migrating mule deer may move greater than 150 miles, across diverse landscapes, and encounter a variety of obstacles and challenges along their journey. Because migratory mule deer far outnumber non-migratory deer, maintaining these migrations is critical to sustaining mule deer numbers throughout much of their range. By observing movements of individual deer over time, researchers determined mule deer use the same route year a�er year. �is consistent use of the same routes annually highlights the importance of conserving migratory corridors. Not all mule deer populations migrate along

well-de�ned corridors. �ere are many instances where deer move along many di�er-ent and scattered routes between seasonal ranges, making the conservation of each of those routes more di�cult.

POTENTIAL RISKS TO MIGRATING DEER AND THEIR CORRIDORSEnergy Development - Recent mule deer research indicated energy development a�ects migratory patterns of mule deer. Speci�cally, mule deer move more quickly through developed gas �elds and sometimes attempt to detour around them. When mule deer have to speed up their migration, they may not be able to track the vegetation “green-up” or access critical “stopover” sites. Also, once mule deer arrive on winter ranges with developed gas �elds they avoid infrastructure (e.g., roads and well pads), which e�ec-tively reduces the size of usable winter range and could result in population decline.

A common misperception is mule deer “acclimate” or “habituate” to energy development, but long-term stud-ies show deer continue to avoid infrastructure more than 10 years a�er development.

Vehicle Collisions - Vehicle collisions can be a major source of mortality for migrating mule deer and a hazard for motorists. Tall (8-foot) fencing can be used to keep deer o� roadways and elimi-nate road crossings, but such fencing also blocks migration routes. Road crossing structures (e.g., underpasses and overpasses) have been constructed to maintain and reestablish migration corridors in many areas of the West. Underpasses and overpasses constructed in Wyoming are used by thousands of deer each year, allowing them to reach important seasonal habitats and improving highway safety for motorists.

Fences - Fences that block migration corridors are a source of mortality to migrating mule deer. Removing or modifying fences to accommodate deer crossing can be an e�ective means to o�set such impacts.

Rural and Urban Expansion – As people continue to expand into rural settings, impacts to mule deer migration corridors and seasonal habitats will increase. With the expansion of residential development, comes more fencing, higher levels of human disturbance, and an assortment of and other obstacles mule deer must avoid or cope with. In some cases, residential development has been so extensive and restrictive that mule deer have simply stopped migrating through those areas.

CONCLUSIONSE�orts to conserve migration corridors are an important component of overall conservation of mule deer in the West because the largest and most productive mule deer herds are migratory. As awareness of the impor-tance of migration corridors grows, conservation e�orts to maintain these corridors and incorporate them into land-use planning processes are imperative. Similar to critical winter ranges, migration corridors need to be considered in local, state, and federal land-use planning in order to sustain current mule deer populations. Common sources of risk to migrating mule deer and their corridors include fences, road crossings, energy development, and residential development. With speci�c maps of migration routes now available, we can identify and prioritize where conservation e�orts should be focused to reduce risks to migrating mule deer and migration corridors. E�ective conservation measures may include road crossing structures, fence alterations or removal, modi�cations to proposed industrial developments, conservation easements, leasing stipulations, and state, provincial, or federal protections available through land-use planning. Mule deer migration corridors are essential to the long-term conservation of this iconic species. Many corridors are more than 100 miles in length and cross through many di�erent land ownerships and agency jurisdictions. �is situation complicates conservation e�orts and requires people work together to develop site-speci�c measures to ensure migrations continue into the future.

UNDERSTANDING MULE DEER MIGRATIONFact Sheet #12



OVERVIEWFences have become a predominant feature on the landscape throughout the West. While fences that limit or direct movement of big game are necessary to protect crops, manage livestock, delineate proper-ty boundaries, or create safe zones along roadways, these same fences can impede or completely block mule deer seasonal migration or daily movements to food, cover, and water needed for survival. Many fence designs are especially dangerous to mule deer because they entrap or entangle their legs and lead to a slow, grisly death. Other fence designs have been developed to minimize impacts to mule deer and other wildlife.

CONSIDERATIONSBefore building a fence, ask yourself “Is a fence nec-essary?” If a fence must be built in mule deer habitat or migration corridors, then several factors need to be considered: purpose of the fence, mule deer abundance, occurrence of daily or seasonal movements, and pres-ence of fawns. Spacing between top wires, on fences using strands of wire, is very important because of the manner in which mule deer draw their rear legs under their bodies as they leap over a fence. If one or both hind legs fail to clear the top wire, the legs may catch between the top two wires, entangling the lower portion

of the leg or legs, resulting in serious injury and o�en death. Fences built on slopes are especially problem-atic; a fence of any height is more di�cult to jump when approached from downhill because e�ective fence height is increased. For example, approaching a fence from the downhill side on a 30% slope e�ectively increases the height by 20 inches. Obviously, on very steep slopes fences become impossible for mule deer to jump without injury or death. Also, where water availability to mule deer is a limited, a small area of perimeter fencing around arti�cial water sources and springs can preclude mule deer use.

FENCES TO ALLOW MULE DEER MOVEMENTAny fence is going to create some impediment and risk to mule deer and other wildlife. However, some fence con�gurations reduce negative impacts. Height of a barbed- or smooth-wire fence on mule deer range should not exceed 42 inches. Space between the top 2 strands should be at least 12 inches. �e bottom strand should be smooth (not barbed) wire and should be at least 18-20” above the ground to allow fawns to pass underneath. Wo-ven wire fences should be avoided because they complete-ly block mule deer fawn movement. If a “sheep-tight” fence is required, a 4-strand wire fence should not exceed 32”. �e bottom smooth wire should be at least 10” above the ground. �ere are a variety of other fence con�gura-tions that minimize impacts to mule deer. In areas where mule deer migrate, it is especially useful to build fences with seasonal “drop down” or adjustable-height sections or to simply leave extra gates open.

FENCES TO EXCLUDE MULE DEERFences may be needed to completely exclude mule deer from hay stacks, gardens, canals, orchards,

and highway rights-of-way. E�ective fencing is needed along highways to direct migrating mule deer to under- or over-passes to facilitate safe road crossing. �ese fences are typically made of woven wire and are 8 feet in height. Oth-er con�gurations using electric fence have proven e�ective, and are usually less expensive than a new 8-foot woven wire fence. In cases where fencing is used to guide mule deer to passage structures on roadways, “jump-outs” must be includ-ed in the design to allow deer trapped in the right-of-way an opportunity to escape.

CONCLUSIONSAll fences, regardless of con�guration, impede mule deer movement across their ranges. Inventory and evaluation of existing fences on the landscape is needed to identify and modify or remove unacceptable fences. Fences should be removed where they are no longer needed or unnecessar-ily impede wildlife movement. When new construction is considered, evaluation whether a fence is necessary is critical. Fences to exclude migrating mule deer from highways and funnel them to road crossings has proven highly successful in decreasing mule deer-vehicle collisions and increasing mule deer survival. Where non-exclusionary fences are necessary,

well designed fence con�gurations reduce risk of impeding mule deer movement to important habitats while similarly reducing mule deer mortality.

UNDERSTANDING MULE DEER AND FENCINGFact Sheet #13

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FERTILITY CONTROL AND MULE DEER POPULATION MANAGEMENTFact Sheet #14

OverviewAt times, deer may be more abundant than desired, especially in urban locales. �e number of deer in an area can be reduced by 1) hunter harvest or culling (i.e., lethal removal), 2) trapping and relocating them elsewhere, or 3) decreasing reproduction. Increasing hunter harvest or culling can be e�ective and humane, and can be used in some urban areas under safe and controlled conditions. Capturing and moving animals is di�cult, time consuming, requires specially trained personnel, carries a risk of disease spread, and translocated animals experience increased stress and mortality as they adjust to new habitats. Where hunter harvest and culling are not possible or are considered socially unacceptable, the use of contraception or surgical sterilization is o�en suggested as an alternative.

Fertility ControlSeveral fertility control techniques have been explored in large, free-ranging mammals including surgical sterilization, hormone implants, and contraceptive vaccines. All methods require capture and marking of treated deer, are logistically challenging, require professional expertise, and involve an ongoing commitment of resources. Surgical sterilization is considered highly invasive requiring anesthesia and the surgical alteration of reproductive tissues. Hormone implants are surgically placed under the skin and must be replaced every couple years. �ere are also concerns about human and predator consumption of deer treated with hormones. Finally, the use of vaccines to control fertility, called immunocontraception, disrupts speci�c functions of the reproductive system and is currently considered an experimental approach in mule deer. Although it is expensive, di�cult to implement, and unlikely to be a practical population control measure, birth control is o�en perceived to be a popular alternative to lethal removal.

ImmunocontraceptivesSeveral immunocontraceptive vaccines have been tried experimentally in the United States and Canada (e.g., SpayVac™, ZonaStat™, and GonaCon™). �ese products stimulate the animal to make antibodies that interfere with some aspect of the reproductive system. SpayVac™ and ZonaStat™ use Porcine Zona Pellucida (PZP) as the antigen to produce antibodies that attach to the surface of the eggs of treated does and prevent sperm from fertilizing the egg; PZP vaccines are ine�ective on males. SpayVac™ can be e�ective for a few years with just a single dose, while ZonaStat™ and others require boosters. GonaCon™, stimulates the production of antibodies against gonadotrophin-releasing hormone (GnRH) which is the primary hormone that turns on the production of reproductive hormones.

Implementing a Deer Population Immunocontraception Program�e success of vaccination to control deer populations depends on 4 factors: 1) access to an e�ective, long-lasting contraceptive vaccine, 2) the ability to treat and mark a high percentage of does, 3) that authorization can be obtained to administer the vaccine, and 4) that adequate resources are available to sustain the program over the required period to achieve a signi�cant decrease in population.

Tests of e�ectiveness of GonaCon™ in free-ranging white-tailed does resulted in two-thirds of the treated deer being infertile the �rst year and about one-half in the second year, which is too limited to be successful. No matter how e�ective the contraceptive agent, if deer are di�cult to capture or if untreated deer can easily enter the population, then fertility control will fail. �e ideal situation for applying contraception is an isolated population with small numbers of easily approachable deer.

A critical component to the successful implementation of the program is that at least 70% of the females in a population must be treated to e�ect a noticeable population reduction. Treatment includes capture, vaccination, and a permanent marking for identi�cation to avoid unintentional recaptures of previously treated animals. �e best time of year to capture deer is o�en winter; however, adult females are usually pregnant at this time. �e vaccines do not a�ect unborn fawns, so there will be a delay in controlling the population and a need to treat the new female fawns born in the spring.

�e process of reducing a free-ranging population by contraception alone is slow at best, even when working with a nearly isolated population. Because of this, a combination of contraception and lethal removal may be optimal. For example, treating less than 70% of the females in a population will be largely ine�ective, so it may be useful to treat a target number of adult females, followed by the lethal removal of unmarked animals of both sexes.

Authorization and CostsCapture, handling, and administration of tranquilizing drugs and vaccines require regulatory approval, specialized training, as well as state, federal, and/or provincial licenses. GonaCon™ is currently the only immunocontraceptive vaccine registered by the U.S. Environmental Protection Agency (EPA) for use in deer (EPA Reg. No. 56228-40).

In the United States, GonaCon™ is registered only for hand-injection in female white-tailed deer (not mule deer) by USDA-Wildlife Services or state wildlife agency personnel. No immunocontraceptive vaccines are licensed in Canada. SpayVac™ is available under experimental permits from the EPA in the U.S. and in Canada under permits from Health Canada.

�e cost of capturing deer varies considerably depending on capture method, but is o�en about $400-600/individual and GonaCon™ costs $25/dose. Additional expenses may include personnel costs associated with consultation, permit application, planning, and coordinating public outreach. Population monitoring and follow-up treatment is necessary to vaccinate untreated females that enter the population and untreated fawns. Implementing immunocontraception is an expensive and long-term commitment. A program to vaccinate only 20-25 adult females would likely cost more than $20,000-$25,000 USD. Currently there are few, if any, situations where this approach would be e�ective and feasible to manage mule deer populations.

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FORESTRY PRACTICES AND MULE DEER HABITATFact Sheet #15

OverviewFrom the Colorado Plateau to the boreal forests, mule deer live in a variety of ecosystems across the West where forested habitats play an important role in their nutrition and survival. Lack of disturbance (primarily from �re suppression and decreased logging activity) has resulted in dense forests that lack the plant diversity and understory production necessary to optimize mule deer nutrition.

What Does a Healthy Forest Look Like for Deer?Mule deer require high-quality forbs and shrubs, and some grasses, to support reproduction, body maintenance, and antler growth. Disturbances (thinning, clear-cuts, prescribed �re, and other forestry practices) encourage understory that provides quality forage for mule deer. A�er timber removal or other treatments have been conducted, biomass of herbaceous vegetation increases in response to decreased competition for sunlight, soil minerals, and precipitation. Overall, a mosaic-type forest is most bene�cial to mule deer, because a mixed landscape will have greater plant diversity, more nutritious forage, and provide areas for fawning, thermal, and hiding cover. Healthy aspen stands, in particular, provide cover and optimal forage for mule deer during the summer.

Bene�cial Forest Practices �e USFS, BLM, and other land-managers have long recognized the importance of conifer forests as wildlife habitat. Habitat manipulations, controlled burns, natural disturbances, annual weather patterns, and changing climate in�uence habitats used by mule deer. In general, mule deer populations increase following favorable weather patterns and forest disturbance, primarily because of increased production of high-quality forage. When implementing habitat projects, such as controlled burns, it is best to conduct them on a large scale to create the favorable mosaic on habitats mule deer prefer and to allow for regeneration of nutritious plants that are important to mule deer (i.e., the restoration areas should be large enough that domestic livestock and big game do not completely consume the regenerating plants).

Depending on location and past management, several forest practices can improve quality of mule deer habitat:

1. Timber harvest (e.g. clear cuts and thinning) to open stands and encourage growth of early successional forage will typically increase vegetative diversity, as well as abundance and quality of mule deer forage for a period of 5-25 years post treatment.

2. Burning (both prescribed and wild�re) to remove diseased and over-stocked stands of trees and shrubs will release site nutrients for increased soil productivity which, along with more sunlight on the forest �oor, will allow for increased forage vegetation to �ourish. Prescribed burning can also be used to maintain forest stands that are currently in good condition.

3. Mechanical and �re disturbance and the removal of encroaching conifer in aspen stands encourages aspen regeneration and increases productivity of nutritious forage during summer.

Other Considerations• Continued �re suppression o�en leads to even-aged stands, trees that are diseased and crowded, conifer encroachment in aspen, and a non-productive forest �oor.

• When planning habitat projects, such as prescribed burning and timber harvest, consideration should be given to maintaining cover for travel corridors within stands, especially for large project areas.

• Weed infestation can be detrimental to wildlife habitat unless aggressive weed-management practices are followed, monitored, and maintained for several years a�er treatments (especially important in sagebrush, where annual grasses, such as cheatgrass are present).

• Over-use of forage can decrease food available to mule deer, especially in low to mid elevations, riparian areas, or aspen groves; however, proper livestock grazing at low densities can be bene�cial to both mule deer and livestock. Grazing distribution, timing, and intensity should be managed to achieve optimal herbaceous species composition, plant vigor, and to maintain residual forage post-grazing.

• State agencies are responsible for managing wildlife, yet most forested habitat is owned and managed by federal agencies or private landowners. Partnerships and collaborative land-management e�orts are essential to ensure conservation and restoration of habitats that bene�t mule deer and other wildlife.

Conclusions and Recommendations• Forest practices should focus on managing for habitats that ensure a mosaic across the landscape, which include forests of early succession, mixed-age classes, old growth, and a healthy understory of forbs, shrubs, and grasses.

• Habitat projects are best implemented on a large scale to ensure plant regeneration can withstand grazing pressure. If disturbance occurs on a small scale, fencing is encouraged. Natural barriers (dropping conifer in a crisscross style to make a natural fence) can be useful around small aspen stands or where standard fencing is impractical.

• Aspen communities are a very important forest habitat type for mule deer during summer. Preserving and enhancing aspen should be a priority for land managers. Tools include mechanical removal of encroaching conifers, burning to remove conifer and stimulate aspen sprouting, disking to stimulate sapling sprout, and fencing if aspen regeneration is inhibited by cattle or

big game.

• Timing of forest practices to avoid disturbance during peak-fawning (usually late May through June) should be considered.

• Sustainable, healthy habitats require that best management practices are followed, such as leaving old-growth forest to provide thermal cover, snow intercept, and seed sources; as well as managing motorized travel, soil stabilization, and invasive species.

• Implement monitoring programs to continue assessing forest health a�er natural or human-caused disturbance to insure quality habitat for mule deer and other wildlife, continued weed management, and use of adaptive management when conditions change.



MULE DEER SHED ANTLER HUNTINGFact Sheet #16

OVERVIEWShed antler hunting has become an increasingly popular activity as a form of recreation and a highly competitive business enterprise. Antlers are commonly used for decorative pieces, furniture, cra�s, medicinal purposes, and even pet chews. Collecting antlers has even developed into a competitive sport among recreational shed antler hunters. Hunting “sheds” generally occurs during the critical winter period when mule deer are most physiologically stressed and are on a sub-optimal diet. During this period, mule deer limit physical activity and movements to reduce weight loss and increase their chances of survival until vegetation green-up in the spring.

CONSIDERATIONSIn parts of the West, antler hunting occurs on a daily basis beginning in November with photographers or people scouting big bucks and their antlers and ending in June with shed antler collection. Most “shed hunting” activities occur during winter and early spring when deer are concentrated on crucial winter ranges. Because of the popularity of mule deer antlers, increasing numbers of collectors are taking to the �eld earlier in the year during and immediately a�er antlers are shed to collect the largest antlers ahead of others. Antler hunters primarily frequent bare ridge tops and the open south facing slopes in January and February. �is activity o�en displaces deer from preferred habitats into deep snow and lower quality habitats for the much of the winter. Survival is likely reduced by the extreme levels of disturbance associated with these activities.

Other disturbances associated with antler hunting also have an impact. Shed antler hunters o�en operate o�-road vehicles (ORVs) and snowmobiles o� established roads searching for antlers. �is is usually illegal and intensi�es the disturbance to wintering mule deer. In some cases, disturbance includes chasing deer over fences hoping antlers fall o� as the buck jumps the fence. Recently, shed antler hunters are employing drones to scout big bucks and for antlers already shed. While others are utilizing “antler traps” that essentially lure bucks into bait sites rigged with wires, ropes or other apparatus to snag antlers and knock them o�. In other instances, some shed antler hunters have been employing the use of domestic dogs trained to �nd and retrieve shed antlers. Some antler hunters have used dogs to chase deer and pick up antlers as they fall o� while the deer is running. Studies have shown when humans are accompanied by dogs, ungulates show heightened �ight (avoidance) responses, longer avoidance and �ight distances, and longer periods of displacement from preferred habitats. �is is likely due to mule deer associating domestic dogs with their natural canid predators.

In addition to mule deer disturbance, antler hunting and associated use of vehicles, especially ORVs, has caused signi�cant habitat and resource damage. Most of the actual antler collection occurs in spring when snowpack is melting and spring rains or snows occur rendering the countryside very wet, muddy, and susceptible to damage by surface disturbing activities including o�-road motorized vehicle use.

Shed antler hunting statutes and regulations have been implemented in some states, but have proven controversial, di�cult to enforce, and ine�ective. Educational campaigns may prove more valuable in the long-term so people recognize the consequences of their actions. Well designed regulations can play an important role in in�uencing human behavior when coupled with information on the negative e�ects of shed antler hunting.

RESPONSIBLE SHED ANTLER HUNTING Mule deer antlers elicit a sense of admiration and curiosity for many. As a result, shed antler hunting has increased in popularity among recreationists, wildlife enthusiasts, sportsmen, and others. Collecting shed antlers may

increase appreciation for mule deer and their habitats and provide a quality outdoor experience for those who ethically participate in the activity. However, shed antler hunting has the potential to stress or displace deer. �e following e�orts should be made while in the �eld to reduce the negative impact of this activity on mule deer:

• Do not chase or harass mule deer or other wildlife – winter is the most critical time for mule deer survival;• Wait until deer have le� the winter range to collect shed antlers; and• Use all vehicles, such as ORVs, responsibly and legally and only on roads or trails open to such use.

CONCLUSIONSShed antler hunting is an engaging and rewarding outdoor recreation opportunity for many, but it can have unintended consequences on mule deer populations. Mule deer are susceptible to stress during winter because of the harsh conditions and reduced available habitat. Stress associated with movement and displacement of mule deer by shed antler hunters adds to their physiological strain and potentially reduces their survival to spring. �is is particularly pronounced when motorized vehicles are used to pursue wildlife. Some states and federal agencies have statutes and regulations to protect wintering mule deer and other wildlife but have had limited success. Certainly the negative consequences of shed antler hunting can, and should, be reduced to ensure this recreation opportunity does not a�ect overwintering mule deer and other wildlife. Education is needed to help ensure the public engages in this activity in an ethical, safe, and compatible fashion.

A product of the Mule Deer Working Group - Sponsored by the Western Association of Fish & Wildlife Agencies - Approved January 2016Produced with support from the Mule Deer Foundation (www.muledeer.org)


WINTER RANGE DISTURBANCEFact Sheet #17

OVERVIEWMule deer attempt to minimize their energy expenditures in winter because of reduced available habitat and low quality forage. Winter disturbance by humans can require deer to expend unnecessary energy, which can a�ect survival and reproduction. Lower survival and reproduction can ultimately reduce the number of deer available for hunting and viewing.

BACKGROUNDOutdoor recreation and energy development are increasing throughout the West. �ese activities can disturb mule deer and prevent them from using preferred habitats. For example, activity and tra�c associated with energy development have been shown to displace mule deer from higher quality range to lower quality habitat. Recreational activities such as hiking, running, mountain biking, skiing, snowshoeing, snowmobiling, and shed-antler hunting can also be a source of stress and avoidance behavior in mule deer. �e predictability, consistency, and level of threat associated with a disturbance will in�uence the avoidance response. Research has shown that people recreating o�-trail can cause greater avoidance behavior by mule deer than on-trail activities. Additionally, recreating with dogs can further increase stress on mule deer because they o�en react more strongly to the perceived threat from dogs.

EFFECTSEven under favorable conditions, mule deer typically eat less and lose weight during winter months. During severe winters, mule deer limit their physical activity to conserve energy which increases their chances of survival until vegetation green-up in the spring. Human disturbance forces mule deer to use more energy and can reduce their body condition to levels that in�uence survival or reproduction. In addition to increased energy use, reacting to human disturbance also diverts time away from important behaviors such as feeding and resting. Finally, females in

poor condition may have smaller fawns that are less likely to survive than fawns born to females in good body condition.

Land managers are encouraged to promote practices that protect mule deer and their habitats. On federal lands, this protection is o�en accomplished through land management planning. Minimizing disturbance to mule deer should be a high priority when balancing energy development, recreation, and other uses on mule deer winter ranges.

RECOMMENDATIONS FOR RESPONSIBLE RECREATION

• Keep your distance from mule deer and other wildlife – winter is the most crucial time for many mule deer populations.• Recreate responsibly and legally by only using open roads and trails.• Focus winter recreation in areas without wintering big game animals. • Keep dogs leashed.• If you see people harassing mule deer, report it to state or provincial wildlife o�cers.• If deer are moving away from you, you are too close!

ENERGY DEVELOPMENT RECOMMENDATIONS• Critical winter ranges on federal lands should be accurately mapped so they can be considered and if possible avoided in leasing decisions. • Develop a comprehensive energy development plan that considers the needs of wintering mule deer. Avoiding crucial habitats, consolidating facilities, and minimizing the amount of vehicular tra�c needed for project maintenance and operations are strategies that can reduce the e�ects of energy development on wintering mule deer.• At a minimum, land management agencies should coordinate closely with state or provincial �sh and wildlife agencies regarding limiting energy development activities during critical winter mule deer survival periods (Nov 30 – April 30), including management of vehicle access that may a�ect important mule deer habitat.• If avoiding and minimizing disturbances are not possible, e�ects should be mitigated with habitat enhancement projects. • Limit tra�c to the extent possible during periods of mule deer activity (within 3 hours of sunrise and sunset).• Recommend energy companies train sta� on how to minimize disturbance on winter range.

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CONCLUSIONSOur activities can a�ect the reproduction and survival of the animals we care about. Actions that disturb wintering mule deer should be avoided. Recreational travel on winter range should be managed through close coordination with the state or provincial �sh and wildlife agency to reduce disturbance when deemed harmful to mule deer. �e collaborative development of best management practices that reduce disturbance will bene�t mule deer populations and conserve this important species for future generations.

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MULE DEER AND THE EFFECTS OF FIREFact Sheet #18

Fire can positively or negatively in�uence mule deer populations by creating habitats that encourage abun-dant growth of forbs, shrubs and grasses. Conversely in lower precipitation zones such as southwestern deserts, �re can destroy important vegetation which may be replaced by less desirable and invasive plants. Many other forms of habitat disturbance (properly managed silviculture, mechanical treatment) can create similar bene�ts, but �re in the right situation is a cost e�ective habitat management tool. Resource managers should appropriately use �re as a management technique to disturb summer and transitional ranges for the bene�t of mule deer.

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OVERVIEW

Fires are natural and essential in creating and maintaining mule deer habitats on many western landscapes. In most of their range, mule deer are adapted to and dependent upon periodic �res. Large burns from the early 1900’s paved the way for population increases in the late 1940’s through 1960’s. Fires thinned forest overstory allowing plant com-munities to produce succulent grasses, forbs, and shrubs. As human settlement increased throughout the west, and �re suppression became a priority, deer habitats su�ered and became overgrown. With improved wild�re �ghting techniques, acreage that burned annually decreased by ten-fold. Lack of �re resulted in a lack of regeneration of young nutritious forage, decreasing habitat quality for mule deer.

BACKGROUND

Plant communities’ progress through a series of stages called succession. Mule deer thrive in early successional stages where �re or other disturbances result in a mosaic of grasses, forbs, and young or rejuvenated shrubs. In plant com-munities where wild�res have been excluded for long periods of time, trees or old deciduous shrubs become the dominate plants. �ese trees suppress understory vegetation by shading the forest �oor and disproportionately using available water and soil nutrients.

Habitat change on a landscape-scale is needed for an entire mule deer popula-tion to gain critical fat reserves. Small scale �res can provide valuable local ben-e�ts to individual mule deer, but may not change plant community composi-tion over a large enough area to make meaningful di�erences to an entire deer population. When wild�res are large enough to bene�t the entire population the resulting fawn production and subsequent population gains are remarkable. Mule deer does with adequate fat reserves give birth to healthier fawns and are more successful in raising fawns to maturity. For example, in 2003, the Bulldog �re in southeastern Utah burned more than 30,000 acres of crucial summer and transitional ranges. A�er the �re, mule deer fawn recruitment went from a 5-year average of 44 fawns per 100 does to an average of 80 fawns per 100 does.

BENEFITS OF WILDFIRE FOR MULE DEER

�is �re provided much needed forage quality and increased quantity for mule deer. Increased body fat bene�ts bucks as well because when body require-ments are met, surplus nutrition is available for larger antler growth. Mule deer entering winter with excellent fat reserves are less susceptible to winter die-o�s because they have more surplus fat to metabolize for energy during the winter.

Large scale wild�res create vegetation in various stages of succession, result-ing in increased forage production. �e ash and char from wild�res releases nutrients back into the soils, increases the moisture holding capacity of soils, and facilitates increased plant growth. Smoke compounds increase germination rates and vigor of some seedlings such as bitterbrush. Additionally, heat from �res can kill parasites and diseases found in plants.

An increase in the �re frequency regime can be detrimental to mule deer in ar-eas where plant communities are at risk of being altered by invasive plants such as cheatgrass, red brome, and medusahead rye grasses. �ese invasive plants may increase following wild�res and reduce or prevent re-growth of desirable vegetation. Many invasive plants start growing before desirable forbs, shrubs, and grasses each year. �is early growth trait allows invasive plants to strongly compete for available soil moisture and nutrients. Invasive plants also mature and dry out earlier than desirable plants, which may cause an increase in wild�re frequency. Increased �re frequen-cy decreases diversity of plant communities that o�er season-long nutrition and creates one that is dominated by a single plant species with limited nutrition for a short period of time.

Suppression techniques and climate conditions have changed and limited the natural occurring �re frequency, which has resulted in increased fuels found on the landscape. In many instances this has ampli�ed the �re intensity, resulting in extremely hot �res. Wild�res that burn too hot can scorch the soil, burn minerals, and limit regenera-tion of herbaceous plants.

Winter range plant communities that evolved with �re, but have not burned in a long time eventually experience destructive burns. �ese burns remove essential forage and hiding/thermal cover deer rely upon during harsh winter conditions. Shrubs used for winter forage, such as sagebrush, take decades to re-establish, leaving these areas with limited value following �res. Burned areas can be rehabilitated with mechanical tools and seeding to help them recover sooner when required.

DETRIMENTS OF WILDFIRE FOR MULE DEER

Resource managers should promote controlled burn or let-burn policies in areas where �res are bene�cial to mule deer and the environment. However, in instances where wild�res pose risks to �re�ghters, property, or public health and safety, resource managers should seek alternative options to improve mule deer habitat. Some examples may include logging, chaining, lop and scatter, mastication and other methods to create early succession plant communities that bene�t mule deer.

ALTERNATIVES TO FIRE



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MULE DEER NUTRITIONFact Sheet #19

Mule Deer Foundation38

Nutrition a�ects every aspect of mule deer population biology and ecology. Nutrition in�uences mule deer body condition, which in turn in�uences reproduction, recruitment, antler growth, home range size, season-al movements, longevity, predator avoidance, and the ability to negotiate changing habitats. No other single factor has such an overriding e�ect on this species.

Mule deer are ruminant animals. Like other deer, mule deer are primarily browsers. Although they will eat forbs and grasses, especial-ly nitrogen-rich new growth, they rely on shrubs and trees for much of their diets. Ruminant animals have evolved with complex, multi-chambered stomachs to consume and make optimal use of vegetative diets. �eir �rst chamber is the rumen where microbial bacteria break down cellulose following physical mastication (chewing) in the mouth. Microbes (bacteria, protozoans, and fungi) produce volatile fatty acids, which are the major source of energy for ruminants. Ruminants must reduce particle size of consumed forage to smaller than 5 mm in size before it can pass from the rumen into the digestive tract and remaining chambers. Old, decadent forage can be harder to digest due to high lignin content in cell walls, which also makes nutrients less accessible. Although ruminants use microbes to digest cellulose, lignin must be broken down through physical mastication. Consequently, as forage quality decreases, passage rate decreases as well. Very �brous, ligni�ed forage is not digested, but excreted over a long period of time. In poor rangeland, there may appear to be a great deal of dry forage on the landscape, but mule deer may bene�t little from eating this forage because they cannot consume adequate quantities to meet their needs for energy, protein, or other nutrients.

Ruminant animals can have di�culties adapting to rapid changes in their diet. �e rumen microbial community must change with season, intake, and diet as speci�c types of microbes are associated with di�erent kinds of forage. Rapid changes in diet during a wet spring or following a wild�re can result in short-term gastrointesti-nal disturbances. More frequently these rapid changes are human induced, such as translocation into new habitat or placement of novel food sources like alfalfa or grain. Grains placed as bait for hunting or trapping may result in over consumption and death from grain toxicity. Historically, well-intentioned emergency winter feeding of high-quality alfalfa to nutritionally stressed ungulates in deep snow

OVERVIEW



resulted in large numbers dying with full rumens that they were incapable of digesting. Ruminants may starve (or su�er from chronic malnutrition) with a rumen full of food—just food that was not possible to be digested adequately. Microbial communities typically require 2–4 weeks to adapt to changes in diets, and gradual dietary alterations over similar time periods are more favorable than are immediate or rapid changes in their diet.

�e relative contribution of reproduction and recruit-ment are o�en di�cult to separate in free-ranging pop-ulations, but both are in�uenced by the body condition and nutritional plane of the maternal female. Although conception is rarely in�uenced by nutrition except for does in extremely poor body condition, poor body condition in young females in�uences the likelihood of carrying fetuses through pregnancy and older does may produce more male fawns. Energy demands for adult females increase dramatically with lactation following the birth of fawns. High quality nutrition is important for fawn growth, maturation rate, and the ability to avoid predators. Summer ranges generally provide higher quality nutrition than do winter ranges and the in�uence on lactation and fawn survival is greater. Large antler size in male mule deer is related to older population age structure and genetic potential, but the nutritional content of the diet has a substantial in�uence on annual antler growth. Due to lower quality and quantity of forage on winter ranges and increased energetic demands during winter months with snow and cold temperatures, mule deer o�en lose body mass throughout the winter. Consequently, the condition in which they enter this period can have an overrid-ing in�uence on their ability to survive winter demands.

Just as with fawn survival, nutrition plays an important role in adult survival. Animals on a high nutritional plane are generally more physically �t and better able to evade predation. Low-quality diets may predispose mule deer to injury, illness, increased overwinter mortality, or in�rmities that may predispose them to predation. Mule deer on a consistently high nutritional plane can survive and reproduce longer than those consuming inadequate forage.

Nutritional demands that change throughout the year drive mule deer distributions and migration patterns. Home ranges for most species in high-quality habitat are smaller in size than those within relatively lower quality habitat; forage quality, quantity, and availability are important factors in determining habitat quality. High quality forage can mitigate factors like disturbance or habitat fragmentation in some situations. O�entimes, mule deer become habituated or even conditioned to the presence of humans and human developments when high quality forage is available. �e enticement of ornamental landscaping and some crops and orchards can result in nuisance or con�ict situations with humans when vehicle collisions, aggressive individual deer, agricultural depredation, or unwanted foraging behavior develops.

Because nutrition a�ects every aspect of the mule deer life cycle, managers must consider these e�ects in virtually every management strategy. Harvest regulations, translocations, predation management, and habitat manipulation are only a few of the management actions in which nutrition must be carefully considered. High quality diets and good nutritional status provides for robust mule deer populations that all citizens can enjoy.

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relationships among mule deer and their predators · relationships among mule deer and their...

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