Cougar range expansion and the benefits of coexistence

On the night of June une 11th, 2011, a young cougar (Puma concolor) was struck and killed by an SUV on the Wilbur Cross Parkway near the coastal town of Milford, Connecticut. At the time of death, the necropsy report indicated that this lean, two- to four- year old, sub-adult male had an empty stomach and porcupine quills embedded into his subcutaneous tissue.  Without any evidence of a captive lifestyle  (not neutered or microchipped), genetic analysis confirmed that this cougar’s DNA matched  that  of the expanding wild cougar population in the Black Hills region of South Dakota.  Camera trap videos, paw print comparisons, and also a genetic trail of fur, scat, and leftover carcasses revealed that this cougar traveled throughout Minnesota, Wisconsin, Michigan, into Canada through  southern  Ontario,  and  then down into New York (approximately 30 miles from Manhattan) before his abrupt demise in southern Connecticut. On the search for a mate and his own home territory, this big cat’s two-year journey covered a distance of nearly 2,000 miles. This more than doubled the previous, longest-known distance of 640 miles that was ever recorded by a dispersing cougar.
Male cougars disperse much further away from their natal ranges as compared to females but rarely do they ever travel more than a few hundred miles. This cougar’s incredible cross-country trek is also the longest known migration of any land mammal ever documented in the United States. What made it even more remarkable was the fact that it was the first confirmed cougar sighting in the state of Connecticut in more than 100 years. Cougars have historically occupied the entire expanse of the United States, back in a time when Native Americans both revered and peacefully coexisted with them. However, that harmony shifted when early European immigrants began to perceive these big cats as major threats to human life and property. By the turn of the twentieth century, these apex predators were hunted to extinction in virtually all areas east of the Rocky Mountains. Records confirm that the last remaining eastern cougar was killed in 1938 near the Maine- Quebec border. The only viable cougar population left in the eastern United States is now found in South Florida. This small Floridian population was saved from the brink of extinction in 1995 through a highly controversial reintroduction of wild cougars from the state of Texas. However, this population of only 80- 100 breeding-aged adults continue to struggle and survive in less than 5% of their historic home range.
As cougars and other large carnivores help stabilize populations of potentially disruptive prey, the 80- year cougar absence in the eastern United States has had an adverse rippling effect throughout the entire region. The East is now above the carrying capacity with the cougar’s preferred prey, the white-tailed deer (Odocoileus virginianus). This unbalanced predator-prey relationship has brought about severe ecological disruptions and huge socioeconomic consequences to many parts of the East.

Ecological Disruption

Deer have become the most prevalent and influential large herbivore in the eastern United States and are increasingly exceeding the environmental limits to many forested ecosystems. The chronic browsing pressure by deer results in tremendous biodiversity loss and produces a negative cascading effect on the health and function of entire forests. Overfeeding by excess deer prevents forests from naturally regenerating, since individual plants, shrubs, and herbaceous layers are damaged and cannot recover. Additionally, the openness to the forest floor alters the habitat composition of the forest and causes a shift in the colonization of non-native plant species. These dramatic ecosystem changes interfere with normal food web interactions and greatly impact the livelihood and survival rates of many animal species found in the forest. The animals most affected are the ground-nesting bird species such as the wood thrush (Hylocichla mustelina), the Eastern towhee (Pipilo erythrophthalmus), and the hooded warbler (Wilsonia citrina). Other affected animals include small mammals like the Allegheny woodrat (Neotoma magister) and the Tuckahoe masked shrew (Sorex cinereus nigriculus). Additionally, numerous reptiles, amphibians, and invertebrates are also greatly impacted. Some examples include the bog turtle (Glyptemys muhlenbergii), the blue- spotted salamander (Ambystoma laterale), and the Appalachian tiger beetle (Cicindela ancocisconensis).

Socioeconomic Costs

Human health and safety are also greatly impacted by the overabundance of deer in the East.  Deer are statistically the most dangerous wild animal to people in the United States. Deer serve as hosts to vectors of several zoonotic diseases such as Lyme disease and other tick-related illnesses.  If left untreated or undiagnosed, Lyme disease can have severe symptoms that include recurrent arthritis, memory loss, and neurological issues. Documented occurrences of these tick-related diseases have reached an all-time high in every eastern state. Additionally, the number of deer-vehicle collisions have skyrocketed to an unprecedented rate of 1.2 million a year.
These collisions in the East have resulted in more than 200 human fatalities, 29,000 injuries, and $2.3 billion dollars in damage costs. Lastly, deer cause the most damage to agricultural operations and private property residences than any other animal in the eastern United States. Extensive crop damage results when deer feed, travel, or rest in agricultural fields. Crop damage costs eastern farmers a combined annual revenue loss of more than $3.5 billion dollars. The crops that experience the most damage are grains, soybeans, corn, lettuce, and tomatoes.

Cougar Range Expansion

Despite the cougar’s intentional extermination in the midwestern and eastern regions of the United States, the cougar numbers in the western United States have rebounded as a result of hunting regulations imposed by most western states throughout the mid-1960’s. However, cougars still only exist in a fraction of their historic home range as they are heavily impacted by human-caused activities such as habitat loss, habitat fragmentation, trophy hunting, poisoning, and predator control. Current data indicates that some western cougars are now dispersing eastward as these anthropogenic stressors continue to increase throughout their western ranges. This movement is crucial for maintaining genetic diversity within populations and is essential for their long-term survival. This long-distance natural dispersal has already facilitated new breeding populations in the Great Plain states of North Dakota, South Dakota, and Nebraska.

Coexistence Benefits

Based on cougar predation rates from western source populations in the United States, the average cougar appears to kill between 30-40 deer a year. Based on this information, it was estimated that cougar restoration in the East would reduce the deer density by as much as 22% over a 30-year period. This could lead to 700,000 fewer deer-vehicle collisions and result in 155 fewer deaths, 21,400 fewer injuries, and a savings of more than $1.6 billion dollars. Another study found that if the deer density were to stabilize in the eastern United States, the most damaged eastern forests could regenerate within two to three decades. Just the predation threat alone affects herbivore behavior by reducing their overall feeding time, altering their forage movements, and limiting successful reproduction by increasing their stress hormone levels. Cougars and other large carnivores also promote healthier herbivore herds by eliminating weak, disease-susceptible individuals. This ensures optimal genetic herd health by restoring the social order of dominance and allowing only the most fit males to breed.

High Risk Perception

Although science has proven that living alongside cougars would actually save far more people from death and injury, cougars (and all large carnivores) are continuously stigmatized as “bloodthirsty” animals with malicious intentions. A huge injustice occurs when these misunderstood animals, such as big cats, wolves, sharks, and others, are villainized in media outlets such as in Hollywood movies or in news  reports. A substantial overestimation of risk is often associated with these animals and it causes most  people to have an irrational fear of them. Cougars, however, have much more to fear from us than we do from them because humans are by far the largest causes of cougar mortality.

Cougars have repeatedly proven that they are not a substantial public threat as there were only 29 human fatalities and 171 nonfatal attacks that occurred in the United States and Canada between 1890-2017. Although these incidents during the past 127 years are extremely serious, they come nowhere close to the 4.5 – 4.7 million Americans that are attacked by domestic dogs (Canis lupus familiaris) each year in the United States. Statistics indicate that approximately 20-30 people die every year from domestic dog attacks, making people ten times more likely to be killed by a domestic dog than by a cougar.
Although the odds of encountering a cougar in the wild are very small and attacks are extremely rare, more cougar attacks have been reported in the western United States over the past 20 years than in the previous 100. These attacks are directly related to the increasing human population and its encroachment into cougar habitat. There is, however, safety in numbers. Solitary hikers are three times more likely to be attacked by a cougar rather than people in a group. See Table 1 for information on how to act when encountering a cougar.

Coexistence Strategies

Since 2005, there have been a total of 466 cougar confirmations in the midwestern United States and five confirmations in the Northeast. Most of these confirmations have gone unnoticed since cougars typically try to avoid contact with people. This was demonstrated by the Connecticut cougar who remained virtually unseen and undetected for two years until that fateful summer night. However, as these big cats are steadily advancing past the Rocky Mountains, they are increasingly sharing more of the same space with humans in areas where they have long been absent. These dispersing cougars will need the full support and acceptance of the public if they are to have any chance of recolonization back into their former home territories.

The fear of human-cougar conflict plays a major role in anti-predator sentiments towards these large carnivores. Overcoming the societal challenges and the “not in my backyard” mentality will ultimately determine if people have the ability and the desire to coexist with them. Solutions to help foster positive public attitudes are essential, and significant investments into age-appropriate educational and public awareness programs should be a top priority. Children should be a primary focus for the purpose of creating future generations of conservation-minded individuals.
Knowledge of the cougar’s long-term valuable impact can also help diminish the negativity and fear that are associated with these apex predators. Information about permanent human influences on the landscape, such as roads and urban developments, should be assessed to gain an understanding of how successful cougars are in avoiding these human disturbances.
Research into potential dispersal corridors should also be encouraged to help cougars safely facilitate their eastward expansion. Lastly, actions to reduce cougar encounters should be recommended by each eastern state’s wildlife agency with the interests of all stakeholders in mind. See table 2 for actions. With more tolerance, insight, and some changes to our lifestyle, perhaps one day our long-lost eastern cougars will once again recover and unobtrusively roam the lands in which they formerly lived.


The cougar’s important predatory influences were not yet recognized when they were successfully eradicated from the eastern United States over a century ago. Without any natural enemies, the ecological and socio-economic evidence is quite compelling that the deer population has become overabundant in the East. Methods such as sport and recreational deer hunting have not proven effective in the management of white-tailed deer and demonstrate that the cougar’s predation pressure in controlling such populations is unmatched. Now that science has proven the value and worth of these big cats, the restoration of a natural predator-prey relationship in the East could be the much-needed solution for deer control. However, this will be for the public to decide. Whether or not cougars will be “allowed” back into the eastern United States, they are incredibly important animals that deserve protection. Not only for their valuable services to both the environment and to society, but also for the intrinsic value that they have in their own right.

Further Reading
Gilbert, S.L., K.J. Sivy, C.B. Pozzanghera, A. DuBour, K. Overduijn, M.M. Smith, J. Zhou et al. 2016. Socioeconomic benefits of large carnivore recolonization through reduced wildlife-vehicle collisions. Conservation Letters: 1-9.
Laundre, J.W. 2013. The feasibility of the north-eastern USA supporting the return of the cougar Puma concolor. Oryx 47(1): 96-104.
Ripple, W.J., J.A. Estes, R.L. Beschta, C.C. Wilmers, E.G. Ritchie, M. Hebblewhite, A.J. Wirsing et al. 2014. Status and ecological effects of the world’s largest carnivores. Science, 343: 151-164.

This article is from issue


2019 Sep