Tails With A Dark Side: The truth about whitetail – mule deer hybrids

By Jim Heffelfinger

Author of the book “Deer of the Southwest” visit his website www.deernut.com to get a copy.

The “Minotaur” of Greek mythology was a creature that was half man and half bull. Hybrids have always fascinated us throughout the history of mankind. Many of our monsters are a mixture of man and beast (Wolfman, Dracula, the Fly). Likewise, consider our heros: Spiderman, Batman, and Cat Woman. Our obsession with creatures that are half one thing and half another extends to our enjoyment of wildlife. Early naturalists often described new animals as a combination of parts from animals already known to man. The mule deer was described by John J. Audubon in 1846 as having fur like an elk but hooves like a whitetail.

Whenever hunters gather, there is always abundant talk about the types of deer from different areas: Kansas whitetails, Montana mule deer, Sitka blacktails, Key deer, Coues deer, Carmen Mountain whitetails, fat Wisconsin does, and wide South Texas giants. Despite all the differences across the country, there are actually only 2 species of deer in the U.S.: white-tailed deer (Odocoileus virginianus) and mule deer (Odocoileus hemionus). The different-looking black-tailed deer of the pacific northwest is actually a type (subspecies) of mule deer.

All native deer in North America are either mule deer or whitetails. On rare occasions, however, we hear of a deer which can not neatly be labeled as one or the other. This mysterious deer looks mostly like a mule deer but has a tail with a dark back-side like a whitetail.

Different species of animals, even closely related ones, are normally kept from breeding by being geographically isolated from one another, or by separating themselves into different types of habitat. If the animals coexist in the same habitat then they generally have different courtship and breeding behavior to prevent interbreeding.

In most areas of the West where both deer species are found, mule deer inhabit the higher mountain areas and whitetails occupy the lower valleys and river systems. This habitat preference is reversed in the southwest where Coues whitetails are found in the mountains above 4,000 feet and the desert mule deer occupy the lower-elevation valleys and foothills. Because of the interspersion of whitetail habitat (mountains) throughout mule deer habitat, the southwest has an extensive zone where the two species coexist. This results in the animals being in close proximity to one another during the breeding season. It is not uncommon to see a group containing both whitetails and mule deer in these areas of overlap.

In the case of whitetails and mule deer, courtship and breeding behavior is different enough that body language and scent cues given off by a female mule deer during rut are not “understood” by a male whitetail and vice versa. Also, in many areas where their range overlaps, the rut peaks at slightly different times for the 2 species. This system of species segregation has worked remarkably well throughout their evolutionary coexistence. However, in rare cases this system breaks down and genetic material slips across the behavioral barrier, resulting in a deer that is half whitetail and half mule deer. This hybridization between the two different deer species is extremely rare but does occur throughout the West where their ranges overlap.

These bucks show characteristics which are intermediate between mule deer and whitetails. Body size and facial features indicate a mule deer but the tail is usually dark chocolate brown or black on top and white underneath. The tail of a hybrid looks very much like a typical whitetail, but is frequently much darker. Ears are normally larger than a whitetail but smaller than a mule deer. The preorbital gland in front of the eye is also intermediate between the deep pits found in mule deer and the shallow depression of whitetails.

What about the antlers? Forget about the antlers; this is a worthless characteristic to judge whether an animal is a hybrid or not. Most documented hybrids have whitetail-like antlers but you can’t count on antlers alone. I have 3 sets of antlers in my livingroom: 2 are whitetails with forked primary tines (G2) and the third is a desert mule deer with 8 long points, all arising from the mainbeam. There is simply too much variation in antlers to serve as a reliable indicator of hybridization. The whitetails in the Carmen Mountains of northern Mexico have been shown to exhibit a high degree of forked antlers like mule deer.

The best feature to determine if a deer is a hybrid is the size of the metatarsal gland, which is located on the outside of the lower portion of the rear legs. This should not be confused with the tarsal glands on the inside of the legs. The metatarsals on mule deer sit high on the lower leg and are 3 to 6 inches long and surrounded by light brown fur. The whitetail’s metatarsals are at or below the mid-point of the lower leg, usually less than 1 inch, and surrounded by white hairs. A whitetail-mule deer hybrid has metatarsal glands that split the difference, usually measuring between 2-4 inches and encircled with white hair.

Two year-old mule deer are most frequently mistaken for hybrids. This is because of their smaller antler development and the fact that the dichotomous branching, producing the big “forks”, usually does not occur until the buck is 3 years old. Young mule deer sometimes give the appearance of a very large white-tailed deer, especially if it’s tail has a dark stripe down the back, as sometimes occurs. Mule deer in some areas, like southern California, have a dark band running down the back of their tails.

Hybrids have been reported from captive facilities as early as 1898 when a whitetail-mule deer cross was produced at the Cincinnati Zoo. Occurrences were later reported from the Zoo in Minot, ND, deer pens in Alberta, and others. Researchers in Tennessee also successfully produced whitetail-blacktail hybrids in a captive situation.

In the 1930s, biologists in Arizona produced hybrids by mating mule deer males to whitetail females and also whitetail males to mule deer females. These matings resulted in 9 hybrid fawns, of which only 4 survived the first few months. The research ended abruptly and the deer had to be released before any meaningful data could be collected. In the 1970s, Gerald Day also produced hybrids in captivity in Arizona. Ten hybrids were born but only 4 lived past 6 months of age. Survival appears to be very low in hybrids even when pampered in a captive facility.

Coues whitetail x desert mule deer hybrid (F1) produced in captivity by Gerald Day in the early 1970s. Note the whitetail-like antlers and tail, but intermediate metatarsal gland on the outside of the lower rear legs. Photo by Gerald Day.

Survival in the wild is even more difficult when food doesn’t come from a feed trough and there’s no fence between them and animals with sharp teeth. To complicate matters, hybrids inherit predator avoidance strategies from both types of parents; the problem is, whitetail and mule deer have drastically different techniques for escaping predators.

The whitetail’s key to escaping is speed. They put their head down, follow established trails, and try to put as much distance between themselves and the predator as possible, as fast as possible. Mule deer, on the other hand, have developed a pogostick-like bounding called “stotting”, where all four hooves hit the ground at the same time. This strategy developed in mule deer because they evolved in wide open and rugged country throughout the West. Their escape by stotting is not as fast as the whitetail’s, but in rugged terrain it is effective for putting obstacles between the predator and the deer. Mule deer can bound over boulders and stumps that the predator must run around.

Research by Susan Lingle using captive animals in Alberta, has shown that stotting is so specialized that only deer that are 100% mule deer can do it. Even a 1/8 whitetail X 7/8 mule deer fails miserably. The hybrid’s escape behavior is chaotic; the deer will typically approach the threat and jump around in confusion. Such behavior is not conducive to passing their genes on to another generation.

Whitetail-mule deer hybrids have also been reported in the wild from Alberta, British Columbia, Nebraska, Kansas, Colorado, Washington, Texas, and Arizona.

Biologists have documented the presence of hybrids in the wild on only a few occasions. The relative scarcity of confirmed hybrids among the hundreds of thousands of deer that have been seen throughout the area of range overlap illustrates how rare they are. Every year numerous reports are received of “hybrid” deer from hunters. Arizona researcher, Gerald Day (who produced captive hybrids) investigated over 200 reports of “hybrids” and did not find a single legitimate whitetail-mule deer hybrid. Most of these hybrid reports come from hunters who have a whitetail tag on the leg of a mule deer and are trying to convince the Game Warden that they are at least half right.

Recent advances in DNA analysis technology has allowed us to look at more definitive things than ears and antlers. The production of proteins in the body is regulated by genes so by analyzing differences between some proteins, researchers can identify what species a sample of tissue came from. Serum albumin is a protein that has proven particularly useful. Analyzing this protein with a process called electrophoresis produces a series of horizontal bands on a gel surface. This protein produces a band in a different location for whitetails and mule deer. When a hybrid is tested, both the whitetail and the mule deer bands are present. The same result can be had by mixing whitetail burger with mule deer burger and running the test on the mixture. There seems to be some exceptions to the unique banding patterns but this test is at least 95% accurate.

In west Texas, managers have reported an increasing trend in the number of hybrids they see on their ranches. In the early 1980s, whitetails and mule deer in a 5-county area were tested using serum albumin and researchers found that on the average 5.6% of the deer they tested were hybrids. Individual ranches ranged from 0% to 24%!

At the same time, other researchers were busy analyzing the genetics of whitetails and mule deer on a ranch in west Texas with a different method. This method looks at mitochondrial DNA (mtDNA), which is a type of DNA that every animal inherits from only its mother. This is useful because a hybrid that has a whitetail mother and mule deer father, will have only whitetail mtDNA (the rest of the DNA will be from both mother and father). If the hybrid was a female, it would continue to pass whitetail mtDNA through it’s daughters and their daughters even if bred by mule deer bucks. After a few generations, the results of these matings would look like mule deer but would have pure whitetail mtDNA from their mother and grandmother.

And that’s apparently what happened; these researchers found that the mule deer on the ranch had mtDNA that was indistinguishable from the whitetails on the ranch. They concluded hybridization was common on this ranch. Even more surprising, a different type of analysis showed that the mtDNA of mule deer on this ranch was more closely related to whitetails from South Carolina than to blacktails (a type of mule deer) from northern California! This relationship indicated, that hybridization must have occurred between mule deer bucks and whitetail does because the whitetail mtDNA they carried was inherited from their mothers.

These findings run contrary to the conventional theory that most hybridization occurs between a whitetail buck and mule deer doe. This theory is based on the different breeding strategies of the two species. The whitetail buck is accustomed to chasing a whitetail doe relentlessly until she allows him to breed. The mule deer breeding behavior is much more relaxed with the doe only moving a few steps if she is not ready. A whitetail doe would run far away from a pursuing mule deer buck, confusing him; but a mule deer doe would not run far from a whitetail buck in pursuit. It seems more likely then, that a persistent whitetail buck would be more likely to breed with a mule deer doe.

Another researcher in Montana used both of these methods (Albumin and mtDNA) to determine the extent of hybridization and found very little, if any, had occurred in that state. Interestingly, like the west Texas study, whitetails and mule deer were found to be more closely related to each other than blacktails and mule deer which are the same species (different subspecies).

This relatively close relationship between whitetail and mule deer and their genetic differences from blacktails has spawned a new theory that the mule deer itself is actually a hybrid form; the result of a mixing of genes from coastal blacktail bucks mating with whitetails does when the glaciers of the last Ice Age receded, bringing the two species together. The resulting offspring then changed drastically over the last 10,000 years in response to environmental conditions. This would explain the similarities between whitetail and mule deer mtDNA. Analysis of the rest of the DNA (nuclear DNA) with Polymerase Chain Reaction-based microsatellites or any of the other rapidly developing techniques will add much to our knowledge of the origin of deer.

This theory is interesting since black-tailed deer actually look like a cross between a whitetail and a mule deer. This observation is not solely mine, nor is it new. Early explorers, Lewis and Clark noted in their journal “the black-tailed fallow deer are peculiar to this coast and are a distinct species, partaking equally of the qualities of the mule deer and the common deer [whitetail]”. In 1939, famous outdoor writer, Jack O’Conner also remarked that a whitetail-mule deer hybrid “more nearly resembles the Columbian blacktail than it does either of its parents.”

Regardless of the origin and evolution of our deer species, whitetail and mule deer hybrids do occur. However, they are extremely rare in the wild and almost impossible to accurately identify on the hoof because of the large variation in characteristics in each species. Some whitetails have characteristics (tails, forehead) which look like mulies and some mule deer may have whitetail-like features (no antler forks, black line on the back of the tail). Hybrids can not be identified with certainty at a distance, and it is highly unlikely that a hunter will see a hybrid while afield. The low number of interspecies matings and the low survival of hybrid offspring reduce the chance of encountering one in the wild to near zero.

This buck was taken by Jason Montagna and confirmed as a hybrid by genetic testing in 2007. He was over 6 yrs old. Weighed over 250 lbs, and was taken in November 2007 in Unit 34b, Arizona.

Arizona’s Predator Problem

by Jim Heffelfinger, Wildlife Biologist

Note: This article was first published in the Winter 1999 issue of Mule Deer magazine.  People interested in reading more about southwestern deer should look for Jim’s upcoming book “Deer of the Southwest” due out in Spring of 2004.

Arizona deer hunters in the 1950s and early 1960s lived in what is commonly referred to as “the good old days.”  Those who hunted at this time speak of deer behind every bush.  Like all good things, this didn’t last; which is fortunate because deer habitat suffered in areas where deer populations were at destructively high levels.  Arizona’s deer population declined in the late 1960s and early 1970s, which caused widespread concern among deer hunters.  Deer populations recovered early in the 1980s only to again decline in the late 1980s to the present.  White-tailed deer have weathered this last deer decline better than mule deer, which are now at their lowest level since the beginning of the deer permit system (1972).

Time and again, deer research conducted in Arizona has found that habitat conditions are what primarily drive deer populations up and down, with other factors like overgrazing, habitat changes, predation, poaching, and human encroachment playing secondary roles.  The helplessness of this reality is very unsatisfying for those of us who want to “do something.”  Like the last mule deer decline in the 1960s and early 1970s, the current decline has brought to the forefront a discussion of predators and their contribution to deer population dynamics.

When deer populations decline, predators become a focus of discussion because they clearly kill a considerable number of deer.  In Arizona, mountain lions are the only consistent predators of adult deer, but coyotes and bobcats efficiently predate young fawns.  There are 3 separate parts to the predator discussion: 1) do predators affect deer populations? 2) can we do anything about it? and 3) should we do anything about it?  These 3 related, but distinctly different, questions are frequently asked as one — What are you going to do about the predator problem?

Do predators affect deer populations? 

Predators eat a lot of deer; how can they not affect deer populations?  Multiplying a statewide lion population estimate by the number of deer eaten annually by a single lion can be an alarming exercise.  However, deer populations in Arizona fluctuate primarily in response to the condition of the habitat.   Lion populations are controlled in a more sluggish way by prey (deer) densities and social interactions between other individual lions.  Coyotes do not eat deer fawns year-round, so their populations vary in response to the density of other prey and food items, which are related to habitat conditions.  Each predator/prey system is different; add an additional predator or prey species and you may have a completely different situation.  Unfortunately, short-term predator studies provide only a quick snapshot of long-term relationships.  The effects of lion predation in the same area may react differently from one decade to the next because of differing characteristics of the other predator populations, prey populations, and habitat conditions.  This diversity of predator/prey relationships results in a myriad of information and opinions that fuel incredibly confusing discussions among biologists, hunters, and interested public.

Charles Elton did a great job expressing this complexity in his 1927 text book, Animal Ecology and Evolution:

“The balance of nature does not exist, and perhaps has never existed.  The numbers of wild animals are constantly varying to a greater or lesser extent, and the variations are usually irregular in period and always irregular in amplitude.  Each variation in the numbers of the species causes direct and indirect repercussions on the numbers of the others, and since many of the latter are themselves independently varying in numbers, the resultant confusion is remarkable.”

Getting to the point:  do predators affect deer populations?  The only truthful and honest answer is, “you bet they do.”  How many deer we have depends on an interrelationship of many different factors which remove deer and affect the addition of deer to the population.  Predators are one of the things that remove deer, but affecting deer populations is often confused with regulating them.  Predators have been shown to accelerate deer declines caused by poor habitat quality and delay the recovery of deer populations after a decline.  However, predators do not cause declines in deer populations or prevent their recovery; predation is not an over-riding deer population driver.

Harley Shaw, for example, studied mountain lions in central Arizona in the early 1970s during the depths of the last mule deer decline.  He concluded that, at a reduced deer density, lions were a major source of mortality contributing to the low deer population, but that level of lion predation alone would not prevent the population from increasing.

Recently, several excellent long-term research projects have illuminated the relationships of lions and mule deer on both sides of Arizona.  In California, researchers  tracked deer populations for some 14 years and lion populations for 8 years.  During that time, the deer population declined from a high of 5,500 in 1984 to fewer than 1,000 in 1990, presumably because of below average rainfall.  The lion population also declined in response to the declining prey base, but the low point of the lion population was not reached until 4 years after the deer population “bottomed out.”  During this lag time, lions may have exerted proportionately greater pressure on the remaining deer.  Lion predation was the major cause of mortality, seriously impacted the deer herd.  However, forage availability and quality subsequently improved with several years of normal rainfall and fewer deer on the range, and the deer population rebounded to about 2,100 in 1997.

In a long-term New Mexico study, lion predation did not impact a deer population that was stable or increasing during years of adequate rainfall.  However, when the study area was hit with a multi-year drought, recruitment declined drastically and lion predation became the major cause of mortality for mule deer and accelerated a decline.

Can we do anything about it?

Whether predators affect deer populations is actually secondary to the question of whether we can do anything about it.  Research in Arizona and Utah showed that when a lion was removed, the vacant territory was filled very quickly by other lions.  Several mountain lion researchers have even theorized that a light to moderate removal of lions may actuallyincrease the density of lions in an area.  Our knowledge of lion behavior and movements indicates that removing adult lions with large territories may result in more younger lions with smaller territories, as younger animals appear to be more tolerant of each other.

Coyotes are extremely resistant and resilient to population reduction.  Computer modeling shows that they can sustain annual losses of anything less than 75% and maintain a long-term stable population by increasing their reproductive rate and moving in from surrounding areas.  Clearly, removing predators from an area is not the same as reducing the predator population.

Deer populations generally peaked in the 1950s and declined in the 1960s.  Predicides, such as 1080, were used extensively to control coyotes from 1947 to 1971.  This is frequently used as evidence that deer populations are a function of predator populations; despite the fact that the deer decline started well before the use of poisons was curtailed.  Moreover, deer populations recovered a few years later when climatic conditions improved again and went on to peak in the 1980s without the use of poisons.  The use of poisons undoubtedly decreased predator populations in some areas, but it does not explain the statewide peak in deer numbers.  Not so coincidentally, 1983 and 1984 were the 2nd and 3rd highest summer rainfall years on record, with the winters of 1982-83 and 1984-85 about 50% above normal.

The high deer populations of the 1980s are sometimes explained by the high fur prices at that time, causing more interest in harvesting predators.  The harvest of predators and furbearers did increase significantly during that time, but how much that higher level of harvest contributed to the increasing deer populations is far from clear.  Based on past deer research and management, it is much more likely that the series of very wet years during that time was the main factor driving the deer populations upward.  Given what we know about the response in predator reproductive rates, it is unlikely this level of trapping (which occurs primarily in winter) significantly reduced the number of coyotes and bobcats at the time of the fawn drop (late summer, after the pups/kittens are born).

How has the statewide ban on leghold traps, initiated in 1993, affected predator populations?  The number of predators taken in traps has declined precipitously, but hunt questionnaire data show that overall harvest (traps and hunter harvest) for coyotes, bobcats, and foxes has risen substantially.  The total coyote harvest increased from 20,671 in 1992 (before the trapping ban) to levels ranging from 22,000 to 37,000 in the last 5 years since the ban.  Many more coyotes are now being harvested annually than before the trapping ban, also, the deer decline started in the late 1980s.  Thus, the lack of trapping does not appear to account for the most recent deer decline.

A 600-acre predator exclosure was established on the 3-Bar Wildlife Area as part of research to determine the causes of fawn mortality in mule deer.  It was found that the survival of fawns was significantly higher inside the exclosure, where the deer were protected from predators.  The protected deer population increased until it was over carrying capacity and started impacting the food available; at that point fawn survival decreased because of nutritional stress.  Even though predators were responsible for a significant loss of fawns outside the exclosure, that part of the deer herd still increased by almost 40% from 1971 to 1976, illustrating the predators’ inability to keep deer populations from recovering when habitat conditions are favorable.

The Kaibab Plateau, rightly or wrongly, has always served as a predator-prey laboratory.  An intensive predator control program implemented during 1905-31 resulted in 781 lions, 4,849 coyotes, 30 wolves, and 554 bobcats being removed.  During these years, the deer population increased dramatically, peaking in 1928 before crashing to a level below the original population due to intensive overuse of forage and destruction of habitat.  Concurrent with this removal of predators, however, was above average precipitation, a ban on doe hunts, and a dramatic reduction in livestock.  There were reportedly 20,000 cattle and 200,000 sheep grazing the Kaibab deer habitat in 1889; by 1924, grazing pressure had been reduced to 4,000 cattle and 3,500 sheep.  Massive predator control during this period undoubtedly contributed to this increase in the deer population, but it is difficult to separate the effects of decreased predation from the other changes occurring at that time.

Another intensive control effort on the North Kaibab took place in the 1950s using poisons to target coyotes.  Another increase in the Kaibab deer population followed, until the deer herd was again destructively high and damaging important forage plants.  Aldo Leopold, the father of modern wildlife management, once wrote regarding the Kaibab:

“A buck pulled down by a predator will be replaced in 3 years, deer habitat destroyed by too many deer may fail to replace itself in as many decades”.

Concerns over the effects of lion predation on the Kaibab herd following the last mule deer decline spurned a joint deer-lion study there in the late 1970s.  Using radio-collars on both deer and lions, researchers documented a large decline in lion numbers on the Kaibab.  Again, the deer population subsequently increased, although again it was during a wet period with abundant forage growth and following a reduction in livestock numbers.  Deer populations throughout the state were also increasing in response to habitat improvement.

As part of a 15-year study in Utah, researchers reduced the mountain lion population by at least 50% yet saw no measurable difference in mule deer numbers nor the proportion of deer killed by lions.  They concluded that the lion control made only a trivial contribution to the number of deer available to harvest during the hunting season.

Intensive coyote removal (usually with poisons) can increase deer populations if climatic conditions are good; data on the removal of lions is less compelling and depends on the intensity of removal.  When a deer population is as high as the habitat can support, there is no room for more deer.  In this case, any deer saved from predation is going to die from another mortality factor or cause the deer population to exceed the carrying capacity of the habitat — to the detriment of deer, habitat, and all deer enthusiasts.  If a deer population is below carrying capacity, well-timed, intensive predator management may moderate a deer decline, accelerate a recovery, or even increase a population.  The problem lies in effecting a significant reduction (in both intensity and area) in predator numbers using the methods currently available.  Traps are no longer legal on public land, predicides are not registered for use anywhere, aerial gunning is not practical in much of the state’s brushy or forested mule deer habitat, and many areas are not suitable to predator hunting because of rough and remote terrain.  More problematic is the uncertainty of future climatic conditions; are we increasing the deer populations at a time when the next few years will be dry and unable to support the increased number of deer?

Should we do anything about it?

We manage prey species, why don’t we manage predator species?  In the early days of game management, predators were not managed — they were persecuted.  Like the medical profession, the wildlife profession has learned a lot since those early days of bloodletting.  Some say the lesson has been too deeply ingrained and predators have been placed on a pedestal as untouchable.  Many people still recall the mass slaughters of yesteryear when the topic of predator management surfaces, and do not realize how common and prolific predators are.

The California Department of Fish and Game lost its ability to manage lions in 1971 as a result of public referendum.  Ironically, so many problem lions are now killed by department personnel (at public expense), that the total annual lion removal is greater than when they were legally taken by hunters.  Several years ago Alaska had researched-based information indicating that predator management could increase moose and caribou populations, yet a public outcry brought their plans to a screeching halt.

Some people claim that wildlife management agencies don’t want to admit there is a predator problem because predator management is not politically correct in today’s environment.  Any agency that ignores the potential social implications of a predator management program stands to lose not only credibility with the public but the ability to maintain management authority over predatory species.  There is a place for short-term predator management in cases of small, isolated populations which have been fragmented by human activities, such as pronghorn populations.  However, predator management for the purpose of increasing deer populations over a large area in the long-term is not feasible.  Localized programs do not make a difference from a statewide perspective and spend funds that could be better used for habitat projects.

The Utah study mentioned earlier showed that a 50% reduction in the lion population did not increase the deer population.  A greater reduction in the lion population would be very difficult to achieve.  If the deer population is not below the carrying capacity of the habitat, there is no room for more deer.  This is also illustrated by the New Mexico lion study, where a reduction of more than 50% in the lion population was followed by a severe drought; the mule deer fawn recruitment and adult survival decreased drastically because of the reduced habitat carrying capacity.  If lion population reduction were done in either of these cases for the purpose of deer management, it would not have been money well spent.  The annual fluctuations of deer habitat carrying capacity in the Southwest add to the difficulty of prescribing predator management.

Predator-prey relationships are complicated and must be discussed on a case by case basis; sweeping generalizations about predation are guaranteed to be false in some areas at some times.  Deer populations dynamics are not simply a matter of one factor determining how many deer we have, but instead are governed by an extremely complex interrelationship of many factors.  Deer hunters and biologists must look realistically at the biological, logistical, and sociological issues surrounding predator management and consider, for each case, whether it is an effective, feasible, or intelligent way to manage deer populations.

West Nile Virus Information

Background

What is West Nile virus?

West Nile virus is an arbovirus (short for arthropod-borne virus) that causes encephalitis (inflammation of the brain). Blood-feeding insects such as mosquitoes transmit arboviruses, including West Nile virus. Most infections with West Nile virus have been identified in wild birds, but the virus can also infect humans, horses, dogs, cats, bats, chipmunks, skunks, squirrels, domestic rabbits, and domestic birds.

Where did West Nile virus come from?

West Nile virus was first identified in the West Nile district of Uganda in 1937, and has since been found in Africa, Eastern Europe, West Asia, the Middle East, and the United States. The strain of virus found in the United States most closely resembles that found in the Mediterranean and Middle East.

How is West Nile virus transmitted?

Mosquitoes draw the virus from infected birds and transmit it to animals and humans through bites. West Nile viral encephalitis develops in animals and humans when the virus multiplies and crosses the blood-brain barrier. West Nile virus is not transmitted directly from person to person, animal to person, person to animal, or animal-to-animal. Ticks infected with the virus have been found in Asia and Africa; however, there are no verified reports of ticks spreading the virus and their role in transmission has not been determined.

What clinical signs are associated with West Nile virus infection?

Horses – The most common sign is weakness, usually in the hindquarters. Weakness may be indicated by a widened stance, stumbling, leaning to one side, and toe dragging. In extreme cases, paralysis may follow. Fever is sometimes evident, as are depression and fearfulness. Approximately 40% of cases of West Nile encephalitis in horses proved fatal during the 1999 outbreak.

Humans – Most infections in humans are relatively mild, with flu-like symptoms including fever, headache, body aches and, in some cases, skin rash and swollen lymph glands. Signs of more severe infections include high fever, neck stiffness, muscle weakness, convulsions, and paralysis. Death rates associated with severe infection range from 3% to 15% and are highest among the elderly.

Other animals – Wild birds infected with West Nile virus in the United States are most often found dead; therefore, descriptions of clinical signs in wild birds are not readily available. Nor have clinical signs associated with West Nile virus infection in dogs, cats, bats, chipmunks, skunks, squirrels, domestic rabbits, and domestic birds been well described. It appears that, although they may be infected, many of these latter species may not develop clinical signs of disease.

How is West Nile viral encephalitis diagnosed and treated?

Diagnosis of West Nile viral encephalitis is based on a history of exposure, clinical signs, and results of diagnostic blood tests.

As for all viral diseases, treatment consists of providing support (e.g., hospitalization, intravenous fluids, respiratory support, prevention of secondary infections, and good nursing care) while the affected individual’s immune system responds to the infection.

Can you get West Nile virus directly from birds?

There is no evidence that a person can get the virus from handling live or dead infected birds. However, persons should avoid barehanded contact when handling any dead animals and use gloves or double plastic bags to place the carcass in a garbage can.

How many types of animals have been found to be infected with West Nile virus?

Although the vast majority of infections have been identified in birds, West Nile virus has been shown to infect horses, cats, bats, chipmunks, skunks, squirrels, and domestic rabbits.

What is the incubation period in humans (i.e., time from infection to onset of disease symptoms) for West Nile encephalitis?

Usually 3 to 14 days.

Prevention

Can West Nile viral encephalitis be prevented?

A vaccine is now available for horses. For other species, limiting exposure to mosquitoes is considered effective prevention. The following actions may reduce the risk of mosquito bites and possible exposure to West Nile virus.

• Check the integrity of screens around your home, porch, and patio.
• During warm months, avoid outdoor activities at dusk and dawn.
• If you must be outdoors during hours when mosquitoes are most active, cover up with shoes, socks, long pants and long-sleeved shirts.
• Use mosquito repellant on exposed skin and spray clothing with repellents containing permethrin or 35% DEET (N,N-diethyl-meta-toluamide) since mosquitoes may bite through thin clothing. When using insecticides or insect repellants, be sure to read and following the manufacturer’s directions for use.
• Eliminate stagnant water from any receptacles in which mosquitoes might breed.

Is DEET safe?

Yes, products containing DEET are very safe when used according to the directions. Because DEET is so widely used, a great deal of testing has been done. When manufacturers seek registration with the U.S. Environmental Protection Agency (EPA) for products such as DEET, laboratory testing regarding both short-term and long-term health effects must be carried out. Over the long history of DEET use, very few confirmed incidents of toxic reactions to DEET have occurred when the product is used properly.

Is there a vaccine against West Nile encephalitis?

No, but several companies are working towards developing a vaccine.

Risk To Humans

Are game hunters at risk for West Nile virus infection?

Because of their outdoor exposure, game hunters may be at risk if they become bitten by mosquitoes in areas with West Nile virus activity. The extent to which West Nile virus may be present in wild game is unknown. It appears that birds often die within 48 hours of exposure so birds that are acting normally pose essentially no risk to hunters.

What should wild game hunters do to protect against West Nile virus infection?

Hunters should follow the usual precautions when handling wild animals. If they anticipate being exposed to mosquitoes, they should apply insect repellents to clothing and skin, according to label instructions, to prevent mosquito bites. Hunters should wear gloves when handling and cleaning animals to prevent blood exposure to bare hands and meat should be cooked thoroughly.

Who is at risk for getting West Nile encephalitis?

All residents of areas where virus activity has been identified are at risk of getting West Nile encephalitis; persons over 50 years of age have the highest risk of severe disease. It is unknown if immunocompromised persons are at increased risk for West Nile virus disease.

Additional Information

Arizona Department of Health Services 24 Hour phone line:
Phoenix Area – 602-364-4500
Elsewhere in Arizona – 800-314-9243

Informational web sites:
Center for Disease Control (CDC) – www.cdc.gov
American Veterinary Medial Association (AVMA) – www.avma.org
Arizona Department of Health Services (ADHS) – www.hs.state.az.us

What You Should Know About West Nile Virus Brochure (PDF, 800 kb)

[highlight1 variation=”orange” textColor=”#191919″]Attention Hunters: Doves Do Not Transmit West Nile Virus[/highlight1]

West Nile Virus (WNV) is a mosquito-borne virus that was first detected in the United States in 1999. The majority of people and animals that are infected with WNV have no symptoms or only a mild illness, such as a fever or headache. The Arizona Game and Fish Department has put this information sheet together to inform and educate dove hunters about WNV. All information contained on this sheet was taken from the Arizona Department of Health Services – West Nile Virus Fact Sheet. Here are some facts to keep in mind as you go out into the field:

• People become infected with WNV only from the bite of an infected mosquito. Birds (including doves) and other animals CANNOT transmit WNV to people.
• WNV is not spread by direct person-to-person or person-to-animal contact. To be fully safe, wear protective gloves when handling or cleaning your dove.
• The most severe illnesses have been seen in crows, jays, ravens and horses, NOT doves.
• Avoid standing water where mosquitos may be living. Avoid being bitten by mosquitos by using insect repellent (35% DEET) and/or wearing lightweight clothing that covers the arms and legs.
• Proper cooking kills the WNV. Consequently, there is no danger associated with eating birds that have been properly cooked.

Other Resources

• AZ Daily Star article about WNV in AZ
• National Biological Information Infrastruture link for WNV info
• AZ Public Health Serivce info
• USGS maps of WNV in the US

Diseases of Coues Deer

CWD is currently NOT known to be present in Arizona. CWD has been documented in New Mexico (click here to read about CWD in New Mexico).

Here are some links to information about other diseases (not necessarily found in Coues deer, but might be of interest to hunters):

• Rabies
• West Nile Virus

Read the article below to learn more about protecting yourself from CWD.

[highlight1 variation=”red”]Hunters Advised to Take Precautions Against Chronic Wasting Disease[/highlight1]

The Arizona Game and Fish Department is advising hunters harvesting meat from deer and elk in other states to take precautions.

Chronic wasting disease (CWD) is a fatal neurological disease that affects deer and elk. It is in a group of diseases called transmissible spongiform encephalopathies, which include bovine spongiform encephalopathy in domestic cattle (also called “mad cow disease”) and scrapie in domestic sheep and goats. Surveillance in Arizona has thus far shown that CWD is not present in our deer or elk populations, but the Game and Fish Department has implemented steps to reduce the potential for this disease so that it doesn’t establish itself in our state.

Very little is known about how the infectious agent of CWD is transmitted from one animal to another. Nonetheless, we are concerned that CWD might be inadvertently brought into our state through the transport of some infected animal tissues.

In 2002, a ban on the import of live cervids (see notice below) – hoofed mammals like deer and elk – was implemented. Now there are some more practical suggestions that may help prevent the spread of CWD. Precautions that should be taken before bringing any harvested animal back into Arizona include:

• Bone out the meat and package (either commercially or privately); do not cut into the spinal cord or remove the head; do not quarter (or other method) the carcass with any of the spinal column or head attached.
• Do not bring the brain, intact skull, or spinal cord back into Arizona.
• If you wish to take the antlers attached to the skull plate, thoroughly scrape and clean tissue from the skull plate using a knife or brush and bleach.
• Thoroughly clean all utensils afterwards with bleach.
• Animal skins or capes (without skull) do not need any further treatment.
• Sawn-off antlers – with or without velvet – do not need further treatment.
• Upper canine teeth of elk (“ivories”) do not need further treatment.
• Finished, taxidermied heads do not require further treatment.

In addition, you may want to have your deer/elk tested for CWD if such a service is available in the state in which you harvested the animal. There may be a fee for such CWD examination. Contact that state’s Fish and Game Department for information on their policies and needs.

At this point, there is no evidence that humans or animals other than deer and elk can get CWD, however, we are asking hunters to take the above precautions in order to protect Arizona’s deer and elk herds from the disease.

In addition, the Department is asking for your assistance in detecting animals that may become infected with this neurological disease in the future. If you ever note deer or elk that are in poor condition, losing hair, droopy ears, stumbling, or have a slow reaction to your presence, please contact the Department at 1-800-352-0700.

Additional information about chronic wasting disease is available from: Chronic Wasting Disease Alliance – www.cwd-info.org

Aging Coues

All wild ungulates (deer, elk, pronghorn, bighorn sheep, etc.), can be aged fairly accurately by examining their teeth. This can be done two ways. One way is to examine the teeth under a microscope and the other is to look at wear and replacement patterns of all the teeth in the lower jaw. Using the number of tines on a buck’s antlers is not an accurate way to estimate age. Bucks in exceptional condition can have more tines than those of the same age which are in poor condition. And older bucks may have heavy beams but fewer points than a young buck.

Aging by counting cementum annuli under a microscope

This method requires the extraction of one of the large front incisors from the lower jaw and slicing the root extremely thin. These slices are then stained and examined under a microscope. As a wildlife biologist, I have pulled and collected hundreds, if not thousands of teeth from ungulates. Most of the time biologists send those teeth to a lab either at their Game and Fish Department or to one in Montana (Matson’s) to be examined. But I have also had jobs where I spent hours cutting, staining and examining slices of deer teeth. This method is very interesting and is similar to counting annual rings in a cut tree trunk. Deer lay down a layer of cementum in their teeth each year. A specialized machine is used to slice microscopic sections off of the tooth root. After staining, the slices of tooth will show annual rings.

Counting cementum annuli is the most accurate method of aging deer older than 3.5 years. In some species you can gain additional information from this technique. Matson’s lab in Montana has correlated the years that a bear has young with thin layers of cementum (perhaps because the bear is putting more resources into the pregnancy). So by looking at a slice of tooth from a female black bear, a biologist can tell how many times the bear has produced young. This works well in bear because they tend to only have young every other year. But for most deer, reproduction is an annual event.

If you have a buck that you would like aged, pull the front incisors from the lower jaw (deer don’t have upper incisors) and contact Matson’s lab for information on how to get it aged. It is just as expensive for the lab to analyze one tooth as it is for 4-5, so you might wait until you have several or get your hunting buddies to collect teeth too.

Make sure when you extract the tooth that you do not break off the root. The easiest way to extract them that I know of is to use a pocket knife to slice down deep into the gum on each side of the tooth. Then wiggle the knife on each side of the tooth so as to loosen things up. Do this on both of the front incisors. Then place the blade of the knife behind the teeth, with the width of the blade parallel to the width of the teeth. Push the knife blade into the gum and gently pry the knife toward you. This should push both teeth forward and down from the rest and then you can slice any remaining flesh from the root to fully extract them.

For more information visit Matson’s Laboratory, LLC – Home Page.

You can email Gary Matson at gjmatson AT montana DOT com

Matson’s Laboratory, LLC
8140 Flagler Road
P.O. Box 308
Milltown MT 59851

Aging by tooth wear and replacement

Another way to use a deer’s teeth to determine it’s age is by looking at wear and replacement. Deer develop their teeth in a predictable pattern. In addition, over time, the teeth are ground down and that wear can give an indication of age. This method is most accurate for deer less than 3.5 years old. For older deer, the amount that the teeth wear down annually varies according to what they are eating. A deer that lives in an environment with a lot of sandy, gritty soil will wear his teeth down faster than one that doesn’t. Many Game and Fish offices have a “deer jaw board” which has examples of deer jaws of known age deer so that one can see how the teeth wear in that particular area. When I get some photos of some jaws, I will post them. An excellent reference for aging all big game animals in Arizona has been published by the Arizona Game and Fish Department. It gives a great description and has pictures demonstrating the tooth replacement patterns.

Click on the image to go directly to the Arizona Game and Fish Department web site. I don’t see this guide listed for purchase at the web site, but you can call the Dept. at (602) 942-3000 to ask where you can purchase a copy. I believe it is only $3.

To use this method of aging a deer, you want to look at the lower jaw. A deer has long incisors on the front part of the jaw and premolars and molars on the back the jaw. In fawns, you will only see four back teeth (3 premolars and 1 molar). A yearling Coues deer will have 3 premolars and the third premolar will have three cusps. The molars of a yearling are still coming in, but you should see three molars with the last molar only partially erupted. A deer that is 2.5 years old will have all its adult teeth in and the third premolar will only have two cusps. There is very little wear evident on the teeth of a 2.5 yr old. Because a deer does not replace any of its teeth after 2.5 years, the teeth start to show more wear with each passing year. The first molar (the fourth tooth on the back part of the jaw) is the one that will show the most wear and is the one to key in on. Look for the width of the dentine (brown parts of top of tooth) compared to the width of the enamel (white part on top of tooth). As the tooth wears it will have wider dentine sections compared to the enamel. And the cusps of the teeth will wear down and become smooth. A deer that is 3-5 years old will still have some cusps to it on the first molar, whereas on an older deer that molar will be very smooth. Here is a link to an online site that shows pictures of this wear pattern. For Arizona specific information, you will want to purchase a copy of the publication put out by Arizona Game and Fish – its only $3 and well worth it.

Coues Deer Sign

Deer leave a variety of sign that can let you know where they have been even if you don’t see them. The most obvious of signs are scat (feces) and tracks. Coues deer scat is in the form of small pellets. The pellets will vary in color from greenish (when really fresh) to brown or black and even gray or white (when really old). The photos below show some of the variation in colors. Coues scat can be clumpy if the deer is eating a really moist diet. Deer scat will also be moist when fresh, but dries fairly quickly. Scat that is somewhat fresh may appear dry on the outside but still be moist on the inside.

All photos by A. Moors.

Scat

Coues deer scat next to rock

There is a quarter in this photo to show scale

This photo shows older scat on the left and newer scat on the right.

Very old scat showing the whitish-gray color.

Tracks

Deer also leave tracks when they travel through an area. Good places to look for tracks include washes, hillsides, and saddles. Also check any area that has muddy soil like around a stock tank, spring or river. Looking at tracks can tell you the size of the animal and what it was doing there (i.e., running, walking, pawing at the ground). White-tailed deer and mule deer have very similar tracks, but mule deer are larger. Mule deer tracks tend to be about 2.5- 3 inches long while Coues tracks tend to be 2 to 2.5 inches long. Sometimes people confuse javelina and whitetail tracks. Javelina tracks are fairly easy to distinguish due to their smaller size (1 to 1.5 inches long) and blunter tips (see photos below).

Tracks can help determine when an animal uses an area.

This photo shows a game trail that crosses a dry sandy wash.

Coues Deer Habitat

The white-tailed deer is highly adaptable. It is found from Mexico and Central America to Canada and throughout the United States. It survives in environments that are subject to extremes in temperature – both heat and cold. It lives in remote areas where few humans ever go and it survives in highly populated areas as well.

Photo courtesy of Wade Sherbrooke, Southwestern Research Station, Portal, Arizona.

So what is good Coues deer habitat? When evaluating habitat, it helps to think of the elements that are needed for any animal – food, water, shelter, and space to live. Good Coues habitat is any area that provides adequate amounts of each of those factors. The best Coues habitat will provide a large diversity of foods by having a mix of open areas and brushy areas. Coues are primarily browsers, so shrubs must be available for them. However, Coues highly prefer forbs and those grow more commonly in open areas such as a grassy meadow or grassland found at the edge of juniper woodland.

Coues deer seem to be most numerous in woodland areas about 4000-6500 feet in elevation that have Madrean evergreen oaks or areas of oak mixed with juniper and pinon pine. However, Coues deer can be found in the more open Sonoran Desert and in Semi-Desert Grasslands. They can also be found in Ponderosa Pine forests. I have selected some photos below to show some of the variety in habitat that Coues deer will use.

The illustration above shows the distribution of Coues deer in Arizona. Those occupied areas tend to be within the 4000-6500 ft. range in elevation. Illustration by Bill Quimby. For a detailed map of the density of Coues deer in Arizona, check out the “Where to Hunt” section. Coues deer are also found in Mexico and southwestern New Mexico.

The best Coues habitat will have several permanent water sources since these deer need them to survive. The home range of a Coues is about 1-2 square miles. Deer density is highest within 0.5 – 1 mile of a good water source. Maghini and Smith (1990) suggested that a density of 1 water source for every square kilometer (approx. 0.5 sq. miles) is best for female Coues. Based on their research in the Santa Ritas in Arizona, Ockenfels et al. (1991) suggested that a density of one water source every 2-3 sq. km would meet deer requirements. They also found that the first 400 m (roughly equal to a quarter mile) around a water source was used far more often than areas greater than 1200 m away from water.

If you are looking for an area that has a high density of Coues deer, look for a place that has a good mix of thick and open vegetation types between 4000-6500 feet in elevation and that has springs or water tanks scattered throughout the landscape within about a 1/2 to 1 mile of each other.

Juniper-oak woodlands with large populations of Coues deer. These two areas have a good mix of white and Emory oak, mesquite, acacia and pinon pine along with the juniper. The variety of topography in these areas provides places for many different types of plants to grow (trees, browse, grass and forbs). This excellent diversity of plants along with good water sources makes these places great habitat for Coues. Deer will feed through the open areas in early morning and evening and move into the thicker areas to bed.

Coues will also use more open habitat of mesquite and prickly pear. There are 3 small bucks near the center of this photo. Photo by A. Moors.

Coues deer feeding between some prickly pear and agave. This deer fed on this open slope in the morning and then moved down into a drainage with thick shrubs for bedding. Coues deer will even use drier areas than this, areas with less grass and more cactus and ocotillo. Photo by A. Moors.

These brushy hillsides provide some good Coues habitat. It can be extremely difficult spotting a Coues deer in this type of habitat. Photos by A. Moors.

This area has a good mix of oak trees, juniper, shrubs and grass. Coues deer feed in the more open areas and bed in the thick vegetation lower in the canyon. Photo by A. Moors.

Ponderosa Pine forest can make good deer habitat if there is enough diversity of other species. A variety of oaks, shrubs, and forbs help make this habitat productive for Coues deer.

This photo shows an excellent interspersion of habitat types. The ponderosa pine forest in the upper left of the photo is supplemented by the brushy hillside. This kind of diversity of plants and structure is great for deer. Coues deer, like all white-tailed deer, spend a lot of time in edges where different types of habitats meet.

Coues deer are amazingly adaptable, they can occupy the ponderosa pine forest shown above or the very dry and more open habitat shown to the right.