gray wolves in the northern rockies

GRAY WOLF POPULATIONS IN THE NORTHERN ROCKIES 1

Gray Wolves in the Northern Rockies and The Region’s

Effects on Population and Distribution

Jeffrey B. Schorsch

Valparaiso University


Gray Wolves in the Northern Rockies and the Region’s

Effects on Population and Distribution

INTRODUCTION

The Northern Rockies has always been an exceptional location for gray wolf populations

to live. Up until the arrival of humans into the area, this species has thrived due to the

distribution of prey, their adaptations, and available habitats in the region. Following local

extinction, it took forty years for the wolves to eventually find their way back into the Northern

Rockies ecosystem, and did so with much support from government wildlife services located

there. Struggles with disease and humans still persist for the recovering gray wolves, but this

hardly limits their expansion and numbers. In fact, every year, the gray wolves seem to increase

their numbers in this rediscovered territory for them. This paper will explore why the Northern

Rockies provide such a great habitat for gray wolves, and how past and current factors in the

region affect the population and distribution as they recover and continue to expand across the

region.

PAST NORTH AMERICAN POPULATION

The gray wolf in North America has adapted and thrived to its environment because of its

availability in prey and ability to survive and hunt together in packs. Due to their success, the

geographic range of the gray wolves has expanded to incorporate almost the entirety of Canada,

and even a leg down into the Northern Rockies. Pierre Jolicoeur traces the evolution of the wolf

and its variations in fur color and skull sizes across Canada and down into the Northern Rockies.

Researchers Bergstrom, Vignieri, Sheffield, Sechrest, and Carlson show a graphic in their

academic journal that projects the distribution of gray wolves in the U.S. Mech describes the use

of fur for survival in the cold and also provides a graphic in his essay that reflects the total wolf

population in Canada. From this information, the wolf distribution can be tracked all the way

into the United States giving an accurate representation of the gray wolf population in North

America, and highlighting the areas where extinction has occurred. In the journal Landscape and


Urban Planning, Fritts et al. provide an accurate account of the extinction of gray wolves in the

Northern Rockies.

P. Jolicoeur’s (1959) research is conclusive on showing the correlation between the

environments and the evolutionary paths of the gray wolves across Canada and down into the

Northern Rockies. First off, the fur color reflects the environment the wolves adapted in. For

example, wolves that adapted in the tundra of Northern Canada have a whitish fur color. On the

opposite side of the spectrum, wolves in Southern territories and the mountainous regions of the

Northern Rockies tend to have darker colored fur. These fur color traits persist because it allows

the wolves to sneak up on prey and provide food for themselves and the pack (Jolicoeur, 1959).

Therefore the wolves that were not as well adapted with fur color that provided camouflage from

prey could not eat because of the lack of ability to hunt efficiently. According to Mech (1974),

fur has also adapted to help the wolf survive in cold environments. Hairs around the neck,

referred to as the mane, tend to be on average about 120 to 150 mm in length. This provides

greater warmth to the gray wolf around the anterior region where it is most susceptible to the

cold. Without such hairs and underfur, the gray wolf could not survive temperatures up to -40

degrees Fahrenheit, which is the minimum temperature they can survive at (Mech, 1974). P.

Jolicoeur’s (1959) research also shows the variation of skull sizes across locations in Canada.

The northern territories of Canada including those in the northwest and northeast tend to have

shorter snouts and wider breadth heads than their counterparts in the south (Jolicoeur, 1959).

This observation can be explained with Allen’s rule which states that mammals in colder

climates tend to have smaller body parts to prevent frost bite.

Even though the Northern Rockies seemed to be a suitable place for gray wolf

populations, extinction in the area occurred. However, this extinction was a human-based

disaster. According to maps provided by Bergstrom et al. and Mech in their essays, wolf

distribution is seen flourishing across the expanse of Canada from Alaska to Quebec, and from

the northwestern shores of Greenland down to the slopes of the Northern Rockies (Bergstrom et

al., 2009; Mech, 1974). This expanse was natural habitat for the wolves until human settlers

began making homesteads in the Montana and Northern Rockies region. According to Fritts et al.


(1994), settlers to the Northern Rockies found an abundance of prey and predators here. This led

to the gray wolves downfall.

New settlers of the Northern Rockies took advantage and hunted big game in the region

which eventually led to higher populations of gray wolves in the Northern Rockies region. This

effect was due to the large amounts of carcasses left by the hunters. This increase was temporary;

because by 1884, the bison population was eliminated, and by 1910, the bighorn sheep, elk, and

deer populations were largely diminished because of game hunters. This led to an increase in

livestock in the newly claimed area as the natural ungulates of the Northern Rockies diminished.

Lack of prey and increase in livestock inevitably caused the wolves to feed on cattle in the

Montana grazing lands of the Northern Rockies. Bounties were placed on wolves by livestock

associations and local governments which caused a mass increase of shootings, poisoning,

trapping and snaring of wolves. The end goal was to eradicated grey wolves from the Northern

Rockies and was accomplished by the mid-1920s by killing hundreds of thousands a year (Fritts

et al., 1994).

NORTHERN ROCKIES RECOVERY

After the extinction of gray wolves from the Northern Rockies, there was a lack of wolf

populations for about 40 years. Not until the 1970s did the populations begin to show signs of re-

establishment in the area. Research by Greffen, Anderson, and Wayne provide information on

how wolves found their way back into the Northern Rockies. More research by Boyd and

Pletscher provides reasons for dispersal and why the populations moved South. Bergstrom et al.,

Ripple et al., and Fritts et al., give a brief history of the American and Canadian recovery effort

put in place for the gray wolves. Such efforts allowed for the increase population and spread of

the gray wolves across the Northern Rockies incorporating three states.

Gray wolves took advantage of dispersal routes from Canada into the Northern Rockies

in the 1970s. Once they arrived, certain factors played a role in why the wolves chose the

habitats they did and their willingness to stay. Dispersal from Canada is not too strenuous for the

wolves considering that their source habitats were about 300 km north of the U.S.-Canadian


border, and considering wolves tend to disperse more than 600 km (Boyd et al., 1999). Geffen et

al. (2004) explains the corridors wolves may have used to find their way back into this region.

Gray wolves will take routes that follow along suitable habitats that avoid other wolf

populations. This avoidance is due to the territorial disputes between wolves that can cause

interspecific competition resulting in mortality (Geffen et al., 2004). Therefore, the wolves will

colonize the suitable habitats of the Northern Rockies because there are available. The studies by

Boyd and Pletscher (1999) show that dispersal of wolves increase in the Northern Rockies when

prey availability is lower (Boyd et al., 1999). Though wolf populations tend to have a high rate

of dispersal, there can be slight genetic differences between Canadian and Northern Rockies

wolves. Usually when a species is highly dispersive, the differences between populations are

nearly indistinguishable because of the lack of isolation. However, in regards to P. Jolicoeur’s

research (1959) as stated above, the wolves disperse in a North-South axis between Canada and

the U.S. and encounter slight differences in climate. Therefore they adapt slight differences in

characteristics in accordance to the climate as seen in the variation of fur color (Geffen et al.,

1999).

The re-dispersal of grey wolves into the Northern Rockies allowed for the continuous

flow of wolf populations in North America to thrive. There are multiple reasons as to why the

dispersal of grey wolves is important, especially back into this extinct region. Boyd and Pletscher

(1999) outline four reasons behind grey wolf dispersal. First, grey wolves need to disperse in

order to avoid inbreeding so there is gene flow between wolf populations. Dispersal increases

outbreeding needed to further the survival and evolution of the species (Boyd et al., 1999). This

would provide a good explanation as to why the wolves continued to disperse back into the

Northern Rockies forty years after their own extinction here. As Canadian wolves descended into

this region of the U.S., they will encounter other newly dispersed species and breed with them.

The second reason Boyd et al. (1999) gives for dispersal is the opportunity for an available food

source. Their studies show that wolf dispersal is higher where prey density is lower (Boyd et al.,

1999). In an area like the Northern Rockies where wolf populations were extinct, newly

dispersing gray wolves from Canada would have a nearly unlimited and unrivaled food supply.

In relation to competition, the third reason for dispersal is to avoid social aggression (Boyd et al.,


1999). By dispersing to this area they have an available food source, but more importantly, wolf

packs do not have to compete over food or territory. The fourth reason for dispersal is the overall

habitat availability (Boyd et al., 1999). In the Northern Rockies, wolves can find territories

where there is low competition and a highly available food source, and a habitat and climate that

is favorable to the wolves. According to Geffen et al. (2004), pups are imprinted with the known

habitats they can thrive in. Since grey wolves disperse at only 2 or 3 years of age, they will

disperse into regions similar to their own in hopes of accomplishing the four reasons stated

above (Geffen et al., 2004). Therefore it is no surprise that these young wolves found a perfect

habitat in returning to the Northern Rockies. These four factors not only played a role in the

dispersal back into the Northern Rockies, but continually play a role in the diverse populations

and movement of wolves in this region today.

Though re-dispersal into the area was the initial reason that gray wolves exist in the

Northern Rockies today, human management has played a vital role in the maintenance, mass

population increase, and distribution spread of the once extinct species. Fritts et al. (1994)

explains that the kick-starter for gray wolves to disperse into the U.S. occurred when Canadian

management programs increased conservation efforts allowing the wolf population in Alberta

and British Columbia to increase and begin to disperse south to find new habitable territory

(Fritts et al., 1994). This migration of just a few propagules into the Northwestern states sparked

human interest, and the wolves were immediately protected by the 1973 Endangered Species Act

(Bergstrom et al., 2009). Then in 1986, gray wolves were reported to be breeding in Glacier

National Park which is the first known time this has occurred in the U.S. since the 1930s. In

response to the new populations inhabiting just south of the international border, Montana,

Idaho, and Wyoming were the initial states to set up recovery plans for these wolves by the U.S.

Fish and Wildlife Services. This recovery plan included each state having an initial goal for 10

packs, or 100 individuals (Fritts et al., 1994).

Soon after, as discussed by Bergstrom et al. (2009), a plan was proposed to re-introduce

gray wolves into Yellowstone National Park. The plan received mass support by those who were

excited to reinstate gray wolves once indigenous to the park. However, the plan was opposed by


ranchers and hunters because it countered their interests and state legislators disagreed with the

lethal control measure for the wolves (Bergstrom et al., 2009). In the mid-1990s, 31 wolves were

re-introduced into the park, and in 2001, this population has reached up to 220 wolves in 21

packs that occupy the Greater Yellowstone ecosystem (Ripple et al., 2003). Just like

Yellowstone, the three other states as a whole have experienced large increases in wolf

populations which exceeded their initial goals and reached 500 individuals. Five years later, the

population of the three states reached 1,300 (Bergstrom et al., 2009). In 2011, gray wolves were

taken off of the endangered species list (Ravindran, 2007). Therefore, due to the Canadian wolf

management system, the wolves resulting southerly dispersal, and then the U.S.’s attempts to

protect and reinstate the species has proven very successful for the growth of the gray wolves in

the Northern Rockies.

EFFECTS OF PREDATOR-PREY RELATIONSHIP

A continuous food source is probably one of the most important factors a species must

take into account when colonizing a new habitat. Survival without one is impossible. Gray

wolves in the Northern Rockies have been able to establish themselves as a top predator over the

ungulates of the region. Research provided by Fritts et al. and additional trophic cascade research

by W.J. Ripple and R.L. Beschta describe the role that wolves play as top predator. Fretts et al.

continues further by describing how prey affects their current and future geographical locations

in the Northern Rockies. Pierre Jolicoeur’s research also shows how the wolf populations are

affected by prey migrations and locations of denser populations.

Hunting prey for the gray wolves is localized to the environment of the Northern

Rockies. Research shows that wolves are found here because this is where the prey is located.

Therefore the prey plays an important role in the dispersal of gray wolf populations. According

to research conducted by Fritts, Bangs, and Gore (1994), gray wolves have wider distributions in

the colder climates of the Northern hemisphere, much like the temperate and frigid mountainous

regions of the Northern Rockies. Gray wolves have highly colonized the Montana river valley

system because of the deer populations there. Additionally, the geography of the area provides

easier travel for the wolf packs (Fritts et al., 1994). Though found in these river valley systems,


gray wolf populations can be found all over the Northern Rockies, and similar to the research by

Fritts et al., Pierre Jolicoeur (1959) shows how the wolf populations correlate with prey densities

and migrations based on research with caribou. It is found that in areas where prey has higher

populations, gray wolf populations in this same area tend to be higher in numbers as well. It is

interesting to note that gray wolves can actually be found migrating amongst its prey as observed

with the caribou (Jolicoeur, 1959). Therefore the probability of finding areas with denser wolf

populations will depend on the density of the prey population on which the wolves feed. As for

the future of gray wolf distribution, according to Fritts et al. (1994), wolves will stay away from

higher elevations due to lack of prey. The factors of snow depth, steepness, and poor overall

habitat keep the prey at lower elevations and therefore wolves will not exceed the elevation of its

food source. Unfortunately, lower elevations occupied by wolf populations will increase human-

wolf interactions that can increase wolf mortality (Fritts et al., 1994).

Gray wolves of the Northern Rockies play a key role in the ecosystem. Because of their

distribution in this vast region, wolves are forced to hunt what they can including almost all four-

legged mammals. Mammals such as white-tail deer, mule deer, moose, bison, and elk all fall into

the diverse food chain of gray wolves. Hunting these mammals also plays a role in the ecosystem

as well. Smaller animals like birds and small mammals are dependent on the carcasses left by the

wolves after the hunt (Fritts et al., 1994). In cold environments, like the high elevations and

slopes of the Northern Rockies, the need for food is without parallel. Smaller animals of the

ecosystem rely on the wolves for killing their food, and the wolves rely on the larger mammals to

feed them. W.J. Ripple and R.L. Beschta (2003) found that wolves play an integral part on the

density of vegetation due to the trophic cascade that occurs. It is observed that in areas where

wolf populations are less prominent, lower growth rates of balsam fir occur. This happens

because where there are low wolf populations; there will tend to be no check on the ungulate

population causing numbers of moose, deer, and elk to rise. These highly populated ungulates

are then feasting on the balsam fir shoots lowering its growth rate (Ripple et al., 2003). In the

Northern Rockies, key roles are reciprocated between wolves and other species of the ecosystem.

Without the other species, including its prey, gray wolves cannot survive, just as certain

vegetation and small animals cannot survive without the presence of gray wolves.


EFFECTS OF DISEASE

Diseases amongst the gray wolves are currently affecting the populations in the Northern

Rockies. However, not only is it currently affecting them but the curse of disease dates back to

the wolves’ initial eradication. In 1905, Montana veterinarians exposed the gray wolves of

Yellowstone National Park to the mange-carrying sarcoptes scabiei. Once infected, sarcoptic

mange added to the high mortality rates of gray wolves in the Northern Rockies and in

Yellowstone especially (Ravindran, 2013). Today, there are several diseases that affect the

populations of this region; three of the most prominent include canine distemper virus, canine

parvovirus, and sarcoptic mange. Not only are pups most susceptible to disease due to their

young age and early development, but the wolves of Yellowstone are especially at risk (Sime et

al., 2007; Ravindran, 2013). Yellowstone wolves are quite vulnerable because they are

transplants in a new environment, and therefore are not adapted to the new habitat and the

diseases that accompany it. This effect can be seen in the pups of Yellowstone who have

declined in survival from 2011 with 34 pups surviving, to only 16 pups surviving in 2013

(Ravindran, 2013). However, the three diseases listed earlier continue to spread across the

Northern Rockies affecting almost all wolf populations.

According to Sime et al. (2007), Canine distemper virus (CDV) is a highly contagious

disease that has affected gray wolves for decades. In the 1980s, CDV was believed to be

responsible for the high mortality rate of pups in Montana. Currently, 91% of tested wolves are

exposed to CDV; and in 2005, CDV was a contributing factor to the high mortality rates of wolf

pups in Yellowstone NP. Canine Parvovirus is another disease that has been highly exposed

amongst the wolves of the Northern Rockies. Of the wolves tested, 100% had been exposed;

however canine parvovirus is not currently a major mortality factor. Sarcoptic mange, carried by

mites, continues to plague wolf packs across the region. Several packs in Montana and four

packs in Yellowstone have been diagnosed with this disease. Three options have come about for

managing sarcoptic mange: eliminate the infected wolves to stop transmission between packs,

treat the wolves, or leave them alone. Option one was rejected because the disease is already

rampant in the ecosystem and therefore would have little effect, and option two was also rejected


because there are multiple doses needed to cure it. It was decided by the Montana Fish and

Wildlife Services to let nature run its course, unless wolves come in contact with humans or

livestock (Sime et al., 2007).

WOLF-LIVESTOCK INTERACTIONS

Recounting back to the early 20th century, humans were responsible for the demise of the

gray wolves in the Northern Rockies. One reason that was explored earlier was trophy hunting,

but the big reason for extinction was for the protection of livestock. In order for wolves to make

a successful comeback in the Northern Rockies, this conflict must be recognized so there is a

peace between wolves and livestock producers. Bangs and Shivik (2001) recount the estimations

of livestock predations by wolves that was drawn up in response to the newly distributed gray

wolves in the region. It was estimated that for every 100 wolves in a recovery area, 10-20 cattle

and 50-70 sheep would most likely be killed by wolf predation. To compensate for the livestock,

producers would be paid between an estimate of $2,000-$30,000 a year for these losses. Also, to

avoid further livestock predation by wolves, it was believed that 10% of the wolf population

must be killed annually to control this. Current numbers show that Montana livestock producers

only suffer an average of 6 cattle and 5 sheep predations a year in contrast to the previous

estimations. In fact, only $150,000 has been given out as compensation for livestock losses since

the wolves’ recovery in 1987. Wyoming, Montana, and Idaho only total a loss of 148 cattle and

356 sheep since the wolves’ reinstatement, and only 6% of the wolf population has beeen

controlled annually to prevent livestock predation. These numbers are signifiantly lower than

what was originally expected (Bangs et al., 2001). With this information it is plain to see that the

wolf management programs of the Northern Rockies have done an exceptional job at preventing

wolf predation on livestock. This is just one step forward to the successful recovery of the gray

wolf.

CONCLUSION

The Northern Rockies were once the roaming and hunting grounds for one of the most

beautiful animals in the world, the gray wolf. Availability of habitats and prey allowed the wolf


to thrive in the slopes and valleys of the region until human settlers moved into the region and

threatened their survival. These settlers hunted the wolves’ prey and drastically decreased the

ungulate populations leaving a scarce food source for the wolves. This caused wolves to turn to

the only prey they could find: the settlers’ livestock. Wolves were hunted down, poisoned, and

trapped for sport and protection of the livestock. By the early 20th century, gray wolves were

completely eliminated from their natural habitat in the Northern Rockies. It was not until 40

years later, when Canadian wolf management services helped the gray wolves survive and

expand, did wolves begin to disperse south across the border. Their current dispersal into the

area plays a critical role in the ecosystem. It is seen that with wolf populations present,

vegetation is no longer diminished from overfeeding by the ungulate populations. Birds and

small mammals rely on the wolf to provide accessible food sources to keep them alive. With a

constantly fluctuating ecosystem, gray wolves play an integral part in maintaining its balance.

Due to the reinstatement of gray wolves and their current human protection, ecosystems of the

Northern Rockies will continue to improve toward the conditions they once were over a hundred

years ago.

I have neither given or received, nor have I tolerated others’ use of unauthorized aid.


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gray wolves in the northern rockies

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