A Review of Variables and Consequences of Cougar (Felis concolor) Persistence in Urban Environments

I. Introduction

Since humans were around 2 million years ago, humans developed special relationships with wildlife. We were the best hunters on land (Strong 2013). Our social roles, man-made tools, and intelligence made us much more effective hunters than the best large social carnivores like big cats and wolves (Strong 2013). In the last 10,000 years we began developing and domesticating agriculture and animals for the use of food, muscle power, and companionship. During the first 4000 years of agricultural expansion, we slaughtered animals, such as rhinos, that were not useful for domestication and took up space. We killed animals that posed deathly threats such as big cats and wolves. If it were not from killing, habitat patchiness caused by deforestation encroached on larger species' ranges making them uninhabitable and hence indirectly causing more extinctions. Within the last 50-60 years, observing the loss of species and advancements in research directed us towards conserving biodiversity, including large potentially dangerous carnivores.  Today, some of these large carnivores are adapting to habitat patchiness in and around urban areas occupied by large numbers of humans.

Even with our developing management plans for the small populations of large carnivores, urban cities that intercept these species' ranges pose many problems. For example, cities contain vegetation and natural resources along with altered climate and habitat patchiness with the abundance of roads. Therefore it is intriguing that multiple carnivore species have acclimated in cities across the world. Cities benefit carnivores when natural prey is scarce because they can prey on livestock, house pets, or utilize anthropogenic food waste. Large carnivores derive incredible benefit from dwelling adjacent to urban areas, but sometimes at a deadly cost (Bateman and Fleming 2011). Bears, coyotes, and cougars can become road kill if there are no safe corridors to cross through cities. Another deadly threat to carnivores is the juxtaposition of illegal hunting and lethal pest control.  Against these factors, some predators do well within urban landscapes such as coyotes and cougars, whereas bears and wolves perish if they encroach upon cities.

Why do some carnivores do well while others do not?  This needs to be understood for their conservation management.  For example, cougars need corridors that are not traversed by humans whereas coyotes are not as sensitive (Bateman and Fleming 2011).  In another instance, wolves may feed on domestic animals during seasons when wild prey is unavailable whereas coyotes stick to mostly wild prey in their diet year round (Bateman and Fleming 2011).  We are unearthing the ecology of these urban carnivores which builds the road to forming management plans for them.  However, research is lacking in areas that go beyond carnivore ecology to study behavior and social structures, reproduction, and compare and contrasting urban versus suburban and rural population dynamics.  Further research on urban carnivores is significant because as more cities are built and habitat availability decreases, we will encounter these creatures more often.  Human-carnivore encounters generally lead to the animal’s death. If we understand how large predators survive around cities, we can create protective management plans.  In this review, I will report ecological discoveries on urban cougars.  They are a large carnivore that repopulated North America after most of them were executed during European conquest.  I will then discuss factors that inhibit or facilitate adaptability of large cougars persisting in cities.  Finally I will discourse about implications of cougars living in urban cities and where research should progress to better understand them.

II. Urban carnivore ecology

Understanding the ecology of urban carnivores will help identify the factors that facilitate living in the city. Physical factors such as available shelter along with resources like food and water play an essential role in selecting habitat. Research has been done on cougars to determine their ecology within and around cities.

Cougar (felis concolor) ecology such as their home range, movements, and diet within cities has been studied to some extent.  The cougar’s range extends from Yukon in Canada down to the South American Andes mountains (figure 1).  In the past, cougars’ city range generally lied on the periphery, called the wild-urban interface (Beier1995).  To visualize this, six individual cougars were tracked by radio telemetry showing they all came within 100 meters of parklands that were heavily occupied by people. (Beier 1995).  Today, cougars continue to habitat the periphery of cities and but are often found further than 100 meters away (Ordenaña et al 2010).  This may be because cougars also have a negative relationship with anthropogenic structures such as roads, lights and houses and prefer native vegetation that provides shelter (Beier 1995 and Ordenaña  et al 2010).  Thus as cities grow, they shy away to remain on the periphery.  Nonetheless, living in this type of range while still proximal to the city allows the cougar to have a diverse diet. 

Cougars are a solitary and adaptable species that have a variety of prey from wild ungulates and rodents to domestic and companion animals (Iriarte 1990).  Living on the periphery allows cougars more dietary breadth from the wild but also domestic animals if wild prey is unavailable (Ordenaña  et al 2010).  In addition, habitat choice on the outskirts of cities may be influenced by adaptability, habitat requirements and interspecific interactions with other carnivores and humans (Ordenaña  et al 2010).  Beyond locating prey, cougars do travel through cities to reach other habitats to establish territory and find mates.

Corridors are areas of suitable habitat that connects wildlife ranges to one another.  Cougars face a deadly problem in urban areas because their habitat across a town is patchy.  The corridors generally available today are unnatural such as golf courses, dirt trails, and freeways (Beier 1995 and Dickson et al).  Anthropogenic corridors tend to be “population sinks” that are positively correlated with a high number of cougar deaths.  Cougar dispersers readily approach highways but stop within 50-100 meters of them to wait until night time to cross.  This still poses a threat especially when 4 of 9 tracked cougars encounter fatal traffic accidents in one study (Beier 1995) as seen in table 1.  In another 5 year study, all but one cougar died crossing freeways (Dickson et al 2005).  Poorly managed corridors or no corridors at all for cougars to travel through could quickly decrease the size of a metapopulation.  This signals a major conservation implication that requires more attention explained next. 

Table 1. Dispersal timing, fate, distance traveled, and intensity of radio tracking for 1 female and 8 male juvenile cougars in southern California, 1990-92 (Beier 1995).

Living near cities that divided the cougars’ range resulted in living on the periphery to satisfy habitat requirements such as vegetative cover, dietary needs, and reduce confrontations with interspecific carnivores and humans (Ordenaña  et al 2010).  In addition, a patchy habitat requires a cougar to travel through a city to find mates, establish territory boundaries and locate food that may be temporarily scarce in the wild.  Traversing through an urban area requires the use of corridors.  Unfortunately today, there are few natural corridors but many anthropogenic ones such as roads which are “population sinks” for cougars today.  Research shows that roads are unsuitable but lacks what types of corridors are appropriate.  Cougars require the availability of some natural areas for their persistence in today’s growing cities (Ordenaña  et al 2010).  Future studies should measure the effect of suitable corridors on the persistence of cougars so they can remain living alongside humans.

III. Factors Influencing Adaptability

            The cougar is an adaptable generalist species that is found in many habitats in the Americas (Iriarte 1990).  Although during the human colonization of the Americas, they were almost wiped out.  Cougars repopulated, spread their range more east in the US, and as cities grow, people are reporting more cougar encounters.  Understanding the biology behind cougar adaptation will help explain their role as urban carnivores which can be applied to apprehending other re-establishing urban carnivores such as wolves and bears (Bateman and Fleming 2012). 

            Cougar’s ability to adapt to various landscapes with different prey within its range makes it one of the more adaptable generalist carnivores (Iriarte 1990).  Outside of urban areas, cougars are found preying on large animals such as ungulates, whereas closer to cities their diet consists more of medium prey items. Although the cougar is well constructed to kill large animals, prey availability and vulnerability influence their prey choice to sometimes smaller animals (Iriate 1990).  Other than the ability to eat multiple prey items, what else contributes to the success of cougars after their prior decimation?

            We know cougars have the largest range of any mammalian carnivore in the US deeming them adaptable (Iriate 1990).  However, the biology, physiology and behavior that supports why they are adaptable is still obscure.  Cougars are extremely solitary and fully carnivorous which are factors that likely make urban living more unlikely (Ordenaña  et al 2010).  In addition, loss of habitat, corridors, and numerous fatal traffic collisions increase the difficulty of living near urban areas (Ordenaña  et al 2010 and Beier 1995).  With these elements supposedly hindering cougar populations, they are still deemed successfully adaptable generalists species.  Perhaps cub dispersal, near or far away from the mother, plays an essential role in the dynamics behind cougar persistence (Beier 1995).  In a study where cubs were tracked after being dispersed by their mother, half were killed by vehicles (Beier 1995).  The reason behind this was due to the number of manmade corridors such as roads versus natural and minimally disturbed landscape.   Thus it is possible that cities with safe corridors allow easier adaptation to living near urban areas.  A comparative focus on the effect of safe versus dangerous corridors has not been tested on cougar population growth.  If we knew the answer behind why cougars are adaptable to urban environments, we could apply similar tests on other carnivores like wolves and bears that are not as successful in population growth. 

IV. Urban Cougar Implications

            As human populations grow and cities enlarge, the chances of cougars encountering humans increases.  Cougars may be more likely to use urbanized resources in order to stay persistent (Bateman and Fleming 2012).  However, using more anthropogenic resources may be short lived as cities become more urban, the wildlife interface obscures, and unprocessed land decreases (Bateman and Fleming 2012).  This may prove difficult for cougars to continue living near cities.  Authors suggest that the future diversity of cougars and other large urban carnivores will decrease due to anthropogenic action (Bateman and Fleming 2012).  Even with diversity dwindling, as we encroach on cougar’s wild lands, we are likely to encounter them more often.  

Consequences of further urban development are cougar-human interactions, and predation on livestock.  The human-cougar interactions continue to be rare, but predation on livestock may be increasing.  Sources show that there are very few attacks on humans (Beier 1995 and Löe and Röskaft 2004).  Nonetheless, cougar attacks on humans that cause injury or fatality result in negative attitudes towards cougar conservation efforts (Löe and Röskaft 2004).  For example, humans respond with illegally hunting or forming hunting-campaigns to kill cougars (Löe and Röskaft 2004).  Evidence suggests that removing the cats or altering human behavior during an encounter can influence the outcome or prevent attacks (Löe and Röskaft 2004).  Understanding what we can do to deter an attack and prevent them will help conserve cougars.  Applying these methods to other carnivores will hopefully yield similar results. Wolves and cougars avoid humans when possible, but data shows that methods such as shouting and throwing objects proves effective in preventing an attack (Bateman and Fleming 2012).  This is important to know because as cities grow and habitat becomes more fragmented, it is likely there will be more encounters.

Further than direct consequences of cougars around cities, accounts of cougars preying on livestock are likely to be frequent if wild prey are less available because of urbanization (Cunningham et al 1999).  Data from cougars preying on livestock in cities of Arizona shed light on whether cougars will prey on cattle more often as their habitat continues to fragment.   Results indicate that cougars will prey more on livestock even when wild ungulates are more abundant(Cunningham et al 1999) see table 2.  This could lead to economic losses and more humans killing cougars for preying on their livestock (Cunningham et al 1999).  However, understanding how cougars will respond to encroachment on wild land will help configure management plans and safety plans for cougars and cattle.

Table 2. Selection of 3 prey species by cougars based on frequency of occurrence in mountain
lion scats and proportion available as determined from aerial surveys, Study Area (Aravaipa-Klondyke), Arizona, 1991-93. (Rabbits, rodents, and desert bighorn sheep were not recorded during surveys) (Cunningham et all 1999).

V. Conclusion

            Effectively understanding the ecology of cougars will reveal what they need to survive the process of human urbanization.  This information can then further be applied to other large carnivores such as wolves and bears, whose urban populations are not as successful as cougars’.  For example, information about the type of corridors that can aid a cougar successfully travel through a city to other habitat can assist in creating corridor management plans that may help wolves and bears in their habitat.  Other than safe corridors and variability in diet, understanding factors leading to cougar success over wolves and bears is still obscure.  Research on cougar biology, physiology, and behavior may help uncover this perplexity.   Albeit, beyond conserving these predators, human and livestock safety is necessary.  This is why researching why cougars attack and how to avoid them requires more research.  What we find can be applied to other large carnivores who are more endangered such as wolves and bears.