Mountain Lion Foundation

12/12/2006

Christopher Papouchis
Conservation Biologist

Executive Summary

In recent years, humans have killed more mountain lions in the American West than at any other time in the past century - greatly exceeding even those years when mountain lions were the target of bounties and government eradication efforts (Figure 1).

From 1997 to 2004 alone, according to records obtained by the Mountain Lion Foundation from state wildlife agencies, nearly 30,000 mountain lions were killed in 11 western states, an average of more than 3,600 each year and an increase of nearly 400 percent since 1970.

The record levels of exploitation in the American West have caused concern among some conservation scientists, particularly in light of a 2002 decision by the World Conservation Union (IUCN), which monitors the status of the world's species through the IUCN Red List of threatened species, to reclassify mountain lions from a species of Least Concern to Near Threatened because of "a declining trend due to persecution and degradation of its habitat and prey base" (Cat Specialist Group 2002).

Figure 1 . Reported human - caused mountain lion mortality in 11 western U.S. states, 1902 - 2000 (Torres et al. 2004)

Large carnivorous mammals  -  the big cats, canids and bears  -  are considered a crucial element in the race to conserve biodiversity because of their role in maintaining ecosystem health and integrity (Terborgh et al. 1999, Ray et al. 2005). According to Ray et al. (2005), "keeping large carnivores is a measure of how we are doing in the battle to save the planet's biodiversity."

In the western United States, the mountain lion is the only remaining large carnivore with viable populations throughout the region (Logan and Sweanor 2001). Consequently, our ability to conserve mountain lions serves as a powerful metric in determining whether we will be successful in conserving biodiversity in in the American West.

State wildlife agencies and commissions have, however, placed little emphasis on conserving mountain lions and continue to manage the species primarily as a resource for sport hunters and as potential sources of conflict with human interests.

It had been widely assumed that mountain lion populations have been increasing throughout the American West (e.g., Riley and Malecki 2001), and that the increasing numbers of mountain lions being killed were having little effect on the status of lion populations. However, since 2003, wildlife officials from four western states have concluded that mountain lion populations in these states have declined in recent years.

Moreover, in 2005, thirteen leading mountain lion scientists and managers cautioned that "Wildlife managers cannot assume that these unprecedented removal levels, especially when combined with the historically high levels of habitat loss and fragmentation that are occurring, have no affect on cougar numbers" (Cougar Management Guidelines Working Group 2005).

Because the primary mission of the Mountain Lion Foundation is to ensure the long - term survival of mountain lions across their historic range, we wanted to develop a more comprehensive understanding of the extent, causes and distribution of human - caused mountain lion mortality in the American West. This report is intended to inform and encourage scientific and public discourse on how mountain lions are managed and conserved in the United States.

Based on our review of mountain lion mortality records provided by wildlife agencies from 11 western U.S. states for the years 1997 to 2004 (when comprehensive data were available for all mountain lion management units), the major findings of this report are:

• In total, humans reported killing 29,387 mountain lions over this 8 - year period.
• On average, 3,673 mountain lions were reported killed each year.
• 56 % of all human - caused mountain lion mortalities in the American West occurred in the four states of Idaho, Montana, Utah and Colorado.
• The states which reported the highest number of kills did not have the most suitable habitat for mountain lions.
• Female mountain lions, which make up the reproductive base of lion populations, comprised approximately 43 % of all the mountain lions killed.
• The primary justifications for killing mountain lions were:
  • 85 % due to sport hunting
  • 10 % in response to real or perceived conflicts with livestock and other domestic animals
  • 2 % in response to real or perceived concerns over public safety
  • 3 % due to other reasons including road kill, incidental killing, poaching, etc.
• Geographic areas with the largest concentrations of kills, defined as mortality hotspots, were:
  • The northern Rocky Mountains (northern Idaho, western Montana and eastern Washington).
  • The northern Utah mountains
  • Utah's High Plateau

The record levels of mountain lions killed in the American West by humans in recent years warrant concern for at least two reasons. First, excessive levels of human caused mortality, termed overkill by scientists, has been identified as one of the primary threats to the long - term viability of mountain lions (Logan and Sweanor 2001).

Overkill increases the vulnerability of mountain lion populations to extinction, particularly populations that are small and isolated (Beier 1993, Logan and Sweanor 2001). Intensive and sustained overkill can even destabilize mountain lion populations spread over large regions, known as metapopulations (Logan and Sweanor 2001).

Although conservation scientists may view declines in mountain lion populations with concern, wildlife managers may consider declines the inevitable consequence or even a goal of management (Mace and Hudson 1999).

In fact, high levels of exploitation by humans have been implicated in the declines of mountain lion populations in Utah and Montana and a metapopulation spreading across northern Idaho, eastern Washington and southern British Columbia (Beausoleil et al. 2003, DeSimone, Montana Fish, Wildlife and Parks, personal communication, Utah Division of Wildlife Resources 2005, Lambert et al. 2006).

The second, and more far reaching, reason for concern is the potential negative effects that the intensive and sustained killing of mountain lions may be having on ecosystem health. There is a growing body of scientific research that mountain lions play a key ecological role and that their loss can negatively impact the health of the natural landscape and eventually lead to the extinction of many other species (Terborgh et al. 2001; Ripple and Beschta 2006). Unfortunately, there is a disturbing lack of research

Effectively conserving self - sustaining and ecologically effective populations of mountain lions in the American West will require actively addressing issues related to exploitation and habitat loss. Focused research to assess the effects of heavy and sustained removals of mountain lions on mountain lion populations and ecosystem health is imperative. More specifically, wildlife agencies and commissions must change their focus from a single - species, utilitarian approach to an ecosystem management approach that considers mountain lions in their ecological context rather than simply as resources for hunters or problems for ranchers, landowners and the general public.

Critically, we must pursue strategies for conservation and management that satisfy the common good  -  such as maintaining ecological health, conserving biodiversity, and representing the full array of human values towards this species  -  rather than merely satisfying the needs of special interests.

To this end, the Mountain Lion Foundation makes the following recommendations:

• Manage mountain lions in the context of their important ecological role in maintaining and restoring ecosystem health. Base management policies and approaches in the principles of conservation biology (Torres et al. 2004).
• Scientifically demonstrate that current management practices are maintaining sustainable and ecologically effective populations of mountain lions.
• Create protected areas and linkages for mountain lions to promote the long - term viability of mountain lion populations.
• Standardize recording and compilation of mountain lion mortalities so that reporting is consistent within and across states.
• Standardize criteria and protocols for the issuance of depredation permits and public safety removals of mountain lions so that these are consistent within and across states.
• Support and initiate research to determine when and where mountain lions play ecologically significant roles and what densities of mountain lions are needed to generate these effects (Ray et al. 2005), and how exploitation of mountain lion populations affects the species' ecological role.
• Implement the following management principles and other recommendations of the Cougar Management Guidelines (CMGWG 2005: 8 - 10), which include:
  • "A large - landscape approach, on the order of thousands of square kilometers of well - connected habitat with thriving natural prey populations, is necessary for healthy, self - sustaining cougar populations."
  • "Given uncertainties about basic demographic parameters [of mountain lion populations], responses of populations to management prescriptions or hunter selectivity, temporal and spatial variation, and understanding that cougar habitat is changing, cougar management should adopt an adaptive management approach."
    • Adaptive management is "A type of natural resource management in which decisions are made as part of an ongoing science - based process. Adaptive management involves testing, monitoring, and evaluating applied strategies, and incorporating new knowledge into management approaches that are based on scientific findings and the needs of society. Results are used to modify management policy, strategies, and practices" (water.usgs.gov/owq/cleanwater/ufp/glossary.html)
  • "Cougar management should reflect the full array of human values and input from all stakeholders."
  • "In light of the diversity of stakeholders and human values, funding for cougar research, management, and conservation should not be derived solely from hunting - related programs."

Introduction

Mountain lions  -  also known as cougars, pumas and Florida panthers  -  are large carnivores native to the western hemisphere that have roamed North America for at least 10,000 years prior to European colonization (Culver 2000). In the United States mountain lions once ranged from the Pacific coast to the Eastern seaboard, where they were first encountered by white settlers who feared and vilified them as killers of deer and threats to livestock and human safety. Along with wolves and grizzly bears they were targeted for extermination through bounty and government sponsored control programs that would continue into the second half of the 20th Century. By the mid - 1900s, mountain lions had been eliminated from the eastern two - thirds of the U.S. with only a small population left in southern Florida. Eventually, an increase in conservation oriented attitudes towards wildlife led to the cessation of the mountain lion bounties and the establishment of protections from indiscriminate killing by the early 1970s in all western states except Texas.

Today, mountain lions are recognized by scientists as playing an invaluable role in maintaining the health and resilience of the natural landscape (Terborgh et al. 2001; Logan and Sweanor 2001; Ripple and Beschta 2006). Since mountain lion populations require large areas on the order of thousands of square miles to survive, conserving habitat for mountain lions can also benefit a myriad of other species (Beier 1996). The mountain lion's wide range, adaptability to a variety of habitats, and superior predatory ability may afford the species a more important ecological role than any other large carnivore in the Americas (Murphy et al. 1999).

However, state wildlife agencies and commissions have placed little emphasis on conservation and continue to manage mountain lions primarily as a resource for sport hunters and as potential sources of conflict with human interests. Under current management policies, lethal control is the primary technique used by wildlife agencies for "managing" mountain lion populations (Murphy et al. 1999).

These policies have led to a significant increase in the number of mountain lions killed by humans in the American West  -  a rise of nearly 400 percent from 1970 to 2000  -  which today greatly exceeds the number killed when the species were subjected to bounties and government eradication efforts (Figure 1; Torres et al. 2004).

Figure 1 . Reported human - caused mountain lion mortality in 11 western U.S. states, 1902 - 2000 (Torres et al. 2004)

These record levels of exploitation in the American West have caused concern among some conservation scientists, particularly in light of a 2002 decision by the World Conservation Union (IUCN)  -  which monitors the status of the world's species through the IUCN Red List of threatened species  -  to reclassify mountain lions from a species of Least Concern to Near Threatened (IUCN 2002). The change in status was initiated by the Cat Specialist Group, an international committee of wild cat scientists, who determined that,

"based on estimates of density and geographic range... the puma's total effective population size is estimated at below 50,000 mature breeding individuals, with a declining trend due to persecution and degradation of its habitat and prey base, and may possibly qualify as Vulnerable if these trends persist, or if better information on its status were available."

In the western United States it has been generally assumed that the increasing rate of exploitation over the past several decades has not negatively effected mountain lion populations. However, in 2005, thirteen leading mountain lion scientists and managers cautioned that "Wildlife managers cannot assume that these unprecedented removal levels, especially when combined with the historically high levels of habitat loss and fragmentation that are occurring, have no affect on cougar numbers" (Cougar Management Guidelines Working Group 2005).

Since the mission of the Mountain Lion Foundation is to ensure the long - term survival of Puma concolor, we initiated this report to document the extent, causes and distribution of human - caused mountain lion mortality in the American West. Specifically, we considered a recent 8 year period, 1997 to 2004, when mortality records were available for all states and management units. Our goal is to inform and encourage scientific and public discourse on how mountain lions are managed and conserved in the United States.

Results

Summary

Humans killed nearly 30,000 mountain lions from 1997 to 2004 in the 11 western states of Arizona, California, Colorado, Idaho, Montana, Nevada, New Mexico, Oregon, Utah, Washington and Wyoming (Table 1). This averages to more than 3,600 lions killed each year.

Table 1. Reported human - caused mountain lion mortalities in 11 western U.S. states, 1997 - 2004. N/A = Not applicable. N/D = state wildlife agency does not use this category.

In 2000, the number of lions reported killed by humans reached an all - time annual peak of just under 4,000 (Figure 2), exceeding 1990 levels by 85 percent and 1980 levels by 290 percent.

Figure 2. Overall human - caused mountain lion mortality reported in the American West, 1997 to 2004.

Female mountain lions constituted more than 40 % of the mountain lions killed in all years from 1997 to 2004 (Table 2), which has important implications for the the social stability of mountain lion populations as discussed below.

Idaho reported the greatest total number of lions killed at more than 5,200, followed by Montana, Utah and Colorado (Table 1). However, there was no apparent correlation between the number of mountain lions killed in each state and the amount of estimated suitable habitat within that state (Logistic Regression, Pearson P = 0.508). In other words, states which reported the highest number of kills did not also have the most suitable habitat for mountain lions. For example, California has the most mountain lion habitat in the American West but reported the fewest mountain lions killed (<1,000), primarily because sport hunting is banned in the state (see below).

Table 2. Percentage of female mountain lions in total human - caused mortality in American West.

Reasons

Human - caused mountain lion mortalities are generally compiled by state wildlife agencies under four general categories. From 1997 to 2004, 85 percent of mountain lions deaths were attributed to sport hunting, 10 percent to depredation, 2 percent to public safety, and 3 percent to other unspecified reasons (Table 1).

The category of sport hunting includes reports of mountain lions killed under state sponsored hunting seasons. The category of depredation includes primarily lions killed in response to threats or attacks on livestock or other domestic animals, including pets. The other category generally includes lions killed in incidents such as being struck by vehicles and incidental trapping, but in seven states also includes lions killed under public safety policies (see below).

However, no standard technique is used by all western states for recording human - caused mountain lion mortalities, particularly those related to depredation, public safety and other reasons. For example, in 10 states reports of mountain lions killed for attacking pets are categorized under depredation along with those killed for threatening or attacking domestic sheep or other livestock. However, Oregon Department of Fish and Wildlife classifies mountain lions killed for attacking pets under the category of public safety. In Washington mountain lions were killed under "preventative" public safety hunts though in many cases no verified threat to human health and safety existed. Interpretation of these figures therefore should reflect these inconsistencies in reporting.

Figure 3. Human - caused mountain lion mortality reported in the American West, 1997 to 2004.

Sport hunting

Nearly 25,000 mountain lions were killed by sport hunters in the American West from 1997 to 2004 (Table 1), an average of more than 3,100 annually. Sport hunting is legal in 10 of the 11 states considered in this report  -  i.e., Arizona, Colorado, Idaho, Montana, New Mexico, Oregon, Utah, Washington and Wyoming. California has not had a sport hunting program since 1972 when then Governor Ronald Reagan signed a legislative moratorium, and mountain lions in that state are presently classified as a specially protected mammal because of a 1990 voter approved ballot initiative.

Idaho reported the highest total number of sport hunting related lion mortalities, followed by Montana, Utah and Colorado. In total, 63 percent of mountain lions killed by sport hunters occurred in these four Rocky Mountain States. Nevada reported the fewest number of lions killed by sport hunters.

Sport hunting related deaths reached a peak in 1997 at 3,391 (89 percent above 1990 levels) and remained above 3,000 until 2001 before dropping to 2,547 by 2004. This decline was attributed primarily to a decrease in hunting related mortalities in Idaho, Montana and to a lesser degree Utah (Figure 3), as a consequence of declining mountain lion populations in these states due to years of intensive sport hunting and other control activities (Beausoleil et al. 2003; Utah Division Wildlife Resources 2005; Lambert et al. 2006, DeSimone, Montana Fish, Wildlife and Parks, personal communication).

In Oregon, sport hunting kills increased steadily from 1997 to 2004. The rise in kills occurred after the Oregon Department of Fish and Wildlife liberalized sport hunting regulations in response to a 1994 ballot initiative that banned the use of hounds for hunting mountain lions and reduced sport hunting related mortalities in Oregon for several years.

Depredation

At least 3,095 mountain lions were killed in the American West from 1997 to 2004 for reportedly threatening or attacking livestock, pets or other domestic animals (Table 1). Sixty - eight percent of these kills occurred in California, Oregon and Arizona. It appears that in general, states with more habitat and larger human population, such as California, reported higher numbers of lions killed for depredation purposes. Overall, there was a slight increasing trend in the number of depredation related mortalities in the American West from 1997 to 2004 (Figure 2).

Public safety

California, Idaho, Montana, Oregon and Washington report mountain lions killed for public safety concerns in their own specific category. Combined, these five states reported a total of 535 mountain lions killed in this category from 1997 to 2004 (Table 1). However, records of public safety related kills were unavailable for Montana in 1997 and for Washington from 1997 to 1999 (at which time public safety related mortalities were reported in the category of other prior to the creation of a public safety category in 2000). As a result, this total understates the actual number of mountain lions killed for reported public safety concerns.

The number of lions killed for public safety concerns were highest in Oregon and Washington with California following a distant third.

Arizona (from 1997 to 2002), Colorado, New Mexico, Nevada, Utah, and Wyoming included lions killed for public safety concerns in the category of other (see below). Wildlife managers in these states (personal communication) have stated that fewer than 5 mountain lions are generally killed each year for public safety concerns in these states.

Because management practices and reporting practices vary from state to state, the number of mountain lions reported killed under the category of public safety is not necessarily representative of actual threats to public health and safety. Public safety guidelines in all the western states permit the killing of mountain lions identified as verified threats to public safety. However, the Washington Department of Fish and Wildlife initiated a preemptive public safety removal program in 2001 in response to citizen concerns about mountain lions that resulted in the killing of more than 160 lions over the next three years. These kills were categorized under public safety, though there was no evidence that any of the lions killed had posed a threat to humans. Furthermore, Oregon Department of Fish and Wildlife includes mountain lions killed for preying on pets under the category of public safety, though there is no scientific evidence that predation on pets is a precursor to an attack on humans.

Other

From 1997 to 2004 more than 880 mountain lions were reported killed in the category of other (Table 1) in 8 western states. Reports of mortalities that occur for reasons other than sport hunting, depredation or, in some states public safety (see below), are usually included in the other category. This category includes but is not limited to mountain lions killed as the result of collisions with vehicles, incidental trapping, illegal killing and research related mortalities, and in Oregon, mountain lions found dead of unknown causes.

California and Montana do not formally compile reports of mountain lions killed for other reasons. Four states (Colorado, Idaho, New Mexico and Utah) include lions killed for public safety concerns in this category in all study years; Arizona included lions killed for public safety concerns in this category from 1997 to 2002 before itemizing them separately. New Mexico includes in this category mountain lions killed in the Unit I management area (southeastern part of the state) as part of a New Mexico Department of Game and Fish program to suppress mountain lion populations in areas with reported livestock losses. Washington Fish and Wildlife ended the use of this category after 1999.

An increasing trend in mortalities classified as other was observed in Arizona, Colorado, Montana, Nevada, Oregon and Utah through the study period (Figure 3). A decreasing trend was observed in Idaho and Wyoming. Overall, from 1997 to 2004 the total number of mountain lions killed in the western U.S. reported in this category exhibited a slightly increasing trend.

Figure 4. Distribution of suitable habitat (indicated by blue shading) for mountain lions in American West.

Mortality Hotspots

Because the western states differ significantly in terms of size and amount of suitable habitat for mountain lions, comparing the number of lions killed in each state provides a poor measure of the intensity of human - caused mountain lion mortalities. A more useful metric for comparison therefore, is to consider the density of kills, or how many mountain lions are being killed each year relative to the amount of suitable habitat.

In total, the 11 western states incorporate about 555 thousand square miles of suitable habitat for mountain lions (Table 1), roughly half of the 1,174 thousand square miles of total land area (Figure 4). If kills were evenly distributed we would find that from 1997 to 2004, on average 6.6 mountain lions were killed annually per 1000 sq. mi. of suitable habitat (Table 1). However, kills were not evenly distributed and the density of mountain lion mortalities varied significantly from state to state (Figure 5).

Figure 5. Annual average number of mountain lions killed per 1000 sq. mi. of suitable habitat in 11 western U.S. states, 1997 to 2004.

Idaho, Montana, and Utah had the highest kill densities, averaging in excess of 10 mountain lions killed each year per 1,000 square miles of suitable habitat (Figure 4). California, which has the most suitable habitat for mountain lions of any state in the American West, had the lowest average annual kill density throughout the period of study, primarily because sport hunting is prohibited.

Considering the significant differences in kill density among states we could postulate that the highest kill densities would occur in states with the densest mountain lion populations. Testing this notion is difficult since no valid statewide estimates of lion population densities exist. Thus we have to consider as a proxy estimates derived for smaller areas based on intensive research projects (Table 3). Comparing these reported population densities to the average kill densities observed from 1997 to 2004 (Logistic regression, Pearson P = 0.21), however, does not support the notion that kill densities were necessarily higher in states with higher reported lion population densities.

Table 3. Mountain lion population densities reported in the literature from studies conducted in western U.S. states.

A more detailed picture of the distribution and intensity of human - caused mortalities can be realized by reducing the focus to the management unit level. Management units  -  also referred to as management areas or simply GMUs  -  are geographic designations created by state wildlife agencies to facilitate wildlife management activities. Table 4 lists the 30 management units with the highest average annual kill density, 1997 to 2004.

Table 4 Thirty management areas with the highest average densities of human - caused mountain lion mortalities, 1997 to 2004.

Mapping these management units revealed three large geographic clusters that we term "mortality hot spots": the Northern Rocky Mountains, the northern Utah mountains, and Utah's High Plateau (Figure 6). Combined, these regions accounted for 56 percent of all reported mountain lions killed yet included only 23 percent of the total predicted mountain lion habitat in the western United States. Each is discussed below.

 1. Northern Rocky Mountains

• The largest concentration of mountain lions killed in the western U.S. occurred in the Northern Rocky Mountains, which encompasses western Montana, northern Idaho and eastern Washington. This region encompasses nearly 50,000 square miles of estimated suitable mountain lion habitat and includes five mountain ranges  -  the Sawtooth, Cabinet, Salmon River, Clearwater and Bitterroot Mountains. Within this region lie the metropolitan areas of Missoula, MT, and Spokane, WA.
• From 1997 to 2004, humans killed at least 6,800 mountain lions in the Northern Rocky Mountain region, 23 percent of all reported human - caused mortalities in the 11 western states. Since this region overlaps three states, each is detailed separately.
  • Northern Idaho - This area includes the Counties of Boundary, Bonner, Kootenai, Benewah, Shoshone, Latah, Clearwater, Nez Perce, Lewis and Idaho. From 1997 to 2004, at least 2,700 mountain lions were killed in this region. Two management areas, the Elk City and Palouse - Dworshak, averaged more than 28 mountain lions killed per 1000 square miles of suitable habitat. More than 90 percent of the mountain lions killed in this area were by sport hunters.
  • Western Montana -Management regions 1, 2 and 3 as designated by Montana Fish, Wildlife and Parks cover nearly 25,000 square miles of suitable mountain lion habitat in thirteen western Montana counties. Combined, these regions averaged 416 lions killed annually for a total of 3,330 from 1997 to 2004. The highest kill densities occurred in Regions 1 and 2, which averaged at least 17 lions killed per 1000 square miles of suitable habitat. As in Northern Idaho, in excess of 90 percent of the mountain lions killed in this area were by sport hunters 
  • Eastern Washington - The Northeastern and Blue Mountains management units of eastern Washington cover approximately 6,500 square miles of suitable mountain lion habitat in the counties of Stevens, Pend Oreille, Spokane, Walla Walla, Columbia, Garfield, Asotin and parts of Okanogan and Lincoln. A total of 856 lions were reported killed in these units from 1997 to 2004, an average of 107 annually. The number of lions killed in these units peaked in 1999 at 147. In the Blue Mountains unit, the kill density averaged 26 annually, and reached 55 lions killed per 1,000 sq. mi. of habitat in 1999. In the Northeastern Washington management area, the kill density averaged 15 annually and reached 20 in 1999 and 2001. Sport hunting was the leading cause of lion mortality in these areas, although there were a number of lions killed for depredation and public safety concerns in the Northeastern unit.

 2. Northern Utah Mountains

• The Northern Mountains Ecoregion of Utah, as designated by the Utah Division of Wildlife Resources, covers more than 7,100 square miles of predicted mountain lion habitat in the counties of Cache, Rich, Weber, Morgan, Davis, Salt Lake, Summit, Daggett, Wasatch and Utah. This region, which includes eight mountain lion management units  -  Cache, Ogden, Morgan/Rich, East Canyon, Creek and Kamas, North Slope, South Slope and Wasatch Mountains  -  reported more than 1,000 mountain lions killed from 1997 to 2004.
• On average, in the Northern Utah Mountains 18 mountain lions were killed annually for every 1000 square miles of suitable mountain lion habitat. The Cache, Morgan / Rich, and Ogden management units ranked among the highest management units with regard to kill density. Ninety - one percent of the mountain lions killed in this region were the result of sport hunting.

 3. Utah's High Plateau

• The Southern Mountains Ecoregion of Utah, as designated by the Utah Division of Wildlife Resources, covers a predicted 12,500 square miles of mountain lion habitat in the Counties of Washington, Iron, Garfield, Beaver, Piute, Wayne, Sevier, Millard, Sanpete, Carbon, and Utah. This region, which includes 10 mountain lion management units, reported more than 1,700 lions killed in total. The annual average kill density for the region was 17 mountain lions per 1000 square miles of predicted mountain lion habitat, with a peak of 24 in 1997. The Manti and Fillmore units ranked near the top of all all management units in average annual kill density. Ninety - one percent of the mountain lions killed in this region were the result of sport hunting.

Figure 6. Mountain lion mortality hotspots in the American West, 1997 to 2004. Colors indicate the average number of mountain lions killed each year per 1000 square miles of suitable habitat, 1997 to 2004, as follows: White = 0  -  .9 lions killed. Yellow = 1  -  9.9. Orange = 10 - 19.9, Red = 20 or more. Gray indicates areas for which no mortality reports were available and include areas under the jurisdiction of the National Park Service, the Department of Defense, tribal authorities, or the Department of Energy.

Discussion

Our review of mountain lion mortality records obtained from state wildlife agencies found that during an 8 - year period from 1997 to 2004, nearly 30,000 mountain lions were reported killed in the 11 western U.S. states of Arizona, California, Colorado, Idaho, Montana, New Mexico, Nevada, Oregon, Utah, Washington and Wyoming. The number of lions killed each year averaged more than 3,600, with an all - time peak of nearly 4,000 lions killed in 2000.

These levels of human - caused lion mortality are unprecedented at least since records were first maintained in the beginning of the 20^th century, and surpass even those levels observed when mountain lions were subject to bounties and government sponsored extermination programs (Torres et al. 2004).

The number of mountain lions killed varied widely among the different western states, with the highest concentrations of mountain lions killed in the Northern Rocky Mountains of northern Idaho, western Montana and northeastern Washington, and in Utah. Overall, the states of Idaho, Montana, Utah and Colorado accounted for 56 percent of all the mountain lions killed from 1997 to 2004. 

Exploitation by humans can have an effect on mountain lion populations in a number of ways, though scientists still have little understanding as to the extent or duration of these changes (Murphy et al. 1999). Extensive removals can reduce mountain lion populations until the habitat is re - colonized by individuals dispersing from surrounding habitat (provided there is connectivity with surrounding populations), which can create a population "sink" effect ( et al. 2000, Stoner 2004).

In areas where mountain lion populations assume a metapopulation structure  -  a group of populations connected loosely by dispersing individuals  -  due to demographic features such as in the Southwest (Sweanor et al. 2000), or human development as in Southern California (Beier 1993;1996), reduction or extinction of mountain lions in one population may destabilize the metapopulation (Sweanor et al. 2000). Killing or removing adult resident mountain lions, particularly females, may affect the dynamics of mountain lion populations and social relations among surviving adults and sub - adults (Murphy et al. 1999). Heavily exploited lion populations also become younger, less productive and socially unstable (Stoner 2004).

Sport hunting is the primary form of exploitation of mountain lions in the West, and the leading cause of all mountain lion mortalities (natural or human - caused) in states where it is permitted (Logan and Sweanor 2001). Eighty five percent of all human - caused mortalities reported from 1997 to 2004 were due to sport hunting.

Over the past several decades a number of state agencies have increasingly liberalized hunting seasons for mountain lions, resulting in a significant rise in the number of mountain lions killed by sport hunters (Dawn 2002). These changes were precipitated by increased interest in mountain lions as a trophy game animal and by the belief that sport hunting addresses reduces the risk of mountain lion attacks on humans and predation on pets, livestock, and big game species desired by human hunters, such as deer, elk and bighorn sheep. However, to date there is no evidence that it accomplishes these goals (Cougar Management Guidelines Working Group 2005, Papouchis 2006).

Ostensibly, hunting management strategies are designed using the best available science to protect hunted mountain lion populations from overexploitation. However, Dawn (2002) analyzed mountain lion sport hunting programs in the American West and concluded that current strategies do not adequately protect populations from overkill and "in some states, may be testing the limits of a population's ability to withstand it."

In fact, intensive sport hunting and predator control over the past decade has caused declines of mountain lion populations in at least four western states. Lambert et al (2006) reported a decline of mountain lion metapopulation spanning northeastern Washington, northwestern Idaho and southern British Columbia due to intensive sport hunting and other predator control activities. Similarly, the Washington Department of Fish and Wildlife acknowledged that "the statewide ... population appears to have declined at this time due to increased female harvest and objectives to address public safety and protection of property" (Beausoleil et al. 2003). Mountain lion populations have also declined in Idaho and Montana after years of heavy and sustained hunting pressure (Nadeau 2003, DeSimone, Montana Fish, Wildlife and Parks, personal communication). Furthermore, in Utah, according to the state's Division of Wildlife Resources, mountain lions populations were intentionally reduced through years of intensive sport hunting and predator control efforts (UDWR 2005).

 Logan and Sweanor (2001) described the state of hunting management in most western states as "a far cry from science." They considered that hunting strategies used by wildlife agencies were analogous to a "sledgehammer approach." Under this approach, the number of lions allowed to be killed by sport hunters and predator control agents is increased more and more,

"until population declines affect hunters to the extent that crude population indices based on harvest data - the number, sex, and spatial distribution of pumas killed, hunter success rates, and hunter testimony - suggest that the puma population has declined. When that happens, presumably hunter off - take has "hammered" the population into a decline phase, the amplitude of which managers cannot fully ascertain" (Logan and Sweanor 2001: 373 - 374).

Because there is no accurate technique for enumerating mountain lion populations over wide areas (Cougar Management Guidelines Working Group 2005), the precise degree to which lion populations in Idaho, Montana, Utah and Washington have declined remains unknown. However, research in Utah suggests the population decline in that state may have exceeded 50 percent (Stoner 2004). Importantly, these findings do not support previous suppositions that mountain lion populations are increasing throughout the American West (Riley and Malecki 2001).

Since even basic information about the size and status of mountain lion populations is often lacking, the setting of hunting quotas is often determined more by local politics rather than sound science (Laundre and Clark 2001). "Game commissions make decisions based on what they hear from their sportsmen constituents," says Greg Tanner, wildlife biologist with the Nevada Department of Wildlife, "We've seen recent trends toward the commission opting to establish year - round [hunting] seasons, increase the annual limit, and reduce the cost of the tag to encourage more lion hunting" (quoted in Peterson 2004). The vulnerability of mountain lions to sport hunters will continue to increase as the result of more hunters in the field and the increased accessibility of remote areas via roads and the use of all terrain motorized vehicles and snowmobiles (Laundr and Clark 2003).

The increasing number of lions killed in response to conflicts with domestic animals and humans also warrants concern. Across the globe, the disappearance of large wild cat species outside of protected areas begins with the loss and fragmentation of their habitat followed by their direct persecution as the result of conflicts with domestic animals or people (Nowell and Jackson 1996). In the American West, as human development continues to expand into mountain lion habitat, the likelihood of negative interactions with mountain lions increases, as does the number of mountain lions killed (Sweanor et al. 2000).

For example, along California's rapidly developing west slope of Sierra Nevada Mountains, the cumulative effects of habitat fragmentation and killing of mountain lions in response to attacks on pets and hobby livestock could lead to loss of this population by 2050 in the absence of conservation measures (S. Torres, CDFG, personal communication).

Although conservation scientists may view declines in mountain lion populations with concern, wildlife managers may consider declines the inevitable consequence or even a goal of management (Mace and Hudson 1999).

If high levels of exploitation are sustained, mountain lion numbers may drop below what conservation biologist Michael Soul and his associates have called an "ecologically effective population density," which they defined as "the population level that prevents undesired changes in a defined ecological setting" (Soul et al. 2005). For example, research in Venezuela (Terborgh et al. 2001) and Zion National Park, Utah (Ripple and Beschta 2006), found that the elimination or absence of mountain lions from an area led to an overabundance of browsing species that denuded vegetation, causing significant ecological changes and rapid declines in biodiversity. In essence, the removal of mountain lions and other large carnivores "appears to lead inexorably to ecosystem simplification accompanied by a rush of extinctions" (Terborgh et al. 1999). Conservation scientists believe "the available evidence clearly suggests that the precautionary principle should be front and center in conservation action dealing with large carnivorous animals (Ray et al. 2005:421). Or as Miller et al. (2002) explained:

"Scientific data increasingly indicate that carnivores play an important role in ecological health. Yet, [lethal] carnivore control has been the center of our management solutions, and it even has been institutionalized by several government agencies. When control is used, there typically is little consideration of the circumstances, season, behavior, or other conditions that affect a carnivore's role in its system. . . . [A]s long as we fail to think in terms of an ecosystem, we will continue to lose diversity despite good intentions, higher budgets, and increasing human effort. In short, management policies based on reducing carnivore numbers has caused, and will continue to cause, severe harm to many other organisms."

Methodology

To identify the extent, causes and distribution of mountain lion mortalities caused by humans we compiled mortality records and data on available mountain lion habitat in the 11 western states of Arizona, California, Colorado, Idaho, Montana, Nevada, New Mexico, Oregon, Utah, Washington and Wyoming. Mortality records were obtained from state wildlife agencies and from state status reports published in the Proceedings of the Mountain Lion Workshops (Padley 1996, Becker et al. 2003, Harveson et al. 2003, Beausoleil et al. 2005). Mortality records were categorized by year [1], state, management area [2], reason (e.g., sport hunting, depredation, public safety, and unspecified other) and sex of animal.

The terminology used for management areas varies from state to state. Arizona reports mortality data by game management unit (GMU). Where GMUs had subunits we pooled data into the GMU to simplify analysis. California reports kill data by county. Colorado and Idaho report kill data by Data Analysis Unit (DAU) which are comprised of several game management units. Montana reports mortalities by GMU and Management Region; we used Regions. New Mexico reports data by Management Zone, which are comprised of several GMUs. Nevada, Utah and Wyoming report data by Hunt Areas. Oregon reports data by Management Zone, which are comprised of a number of GMUs. Washington reports kill data by Cougar Management Units, each of which contain several GMUs. We will simplify the terminology and reference areas as management units.

For states that reported mortalities by harvest year (which overlap calendar years) we report by the year in which the season began (e.g., 1998 - 1999 listed as 1998) to facilitate inter - state comparisons. States reporting lion mortalities by calendar year included Arizona, California, Idaho, Oregon and states reporting mortalities by harvest year included Colorado, Montana, Nevada, New Mexico, Utah, Wyoming, and Washington. This report focuses on human - caused mortalities from 1997 to 2004, the longest recent period for that we were able to acquire kill mortality reports records for all western states and management units.

Because states (and management units) differ with regard to the amount of suitable mountain lion habitat contained within their borders, comparing absolute number of mountain lions provides insight into the extent but not intensity of human - caused mountain lion mortality. Therefore, we standardized mortality by calculating an annual kill density (defined as number of mountain lions killed per 1000 square miles of suitable mountain lion habitat) for each state and management area . This approach provides a useful metric for evaluating the intensity of exploitation across the various western states and management areas. However, since methods of classifying and estimating the amount of suitable habitat vary among states it should be considered a more accurate measure of relative kill density when comparing management units within the states than across states.

To determine the extent of suitable habitat for mountain lions in each state we used a combination of two sources: 1) predictions and maps of suitable mountain lion habitat generated by the national gap analysis program (GAP; see www.gapanalysis.nbii.gov) when available; and 2) estimates derived by state wildlife agencies. Table 5 contains a summary of sources and methods used for deriving estimates of suitable habitat for mountain lions.

Table 5. Sources and methods for estimating amount suitable mountain lion habitat in states and management units in the American West

At the time of our analysis, GAP reports that included numerical predictions of suitable mountain lion habitat were available for California (Davis et al. 1998), Colorado (Schrupp et al. 2000), Idaho (Scott et al. 2002), Montana (Redmond et al. 1998), New Mexico (Thompson et al. 1996), Utah (Edwards et al. 1995), Washington (Cassidy 1997), and Wyoming (Merrill et al. 1996). The GAP report for Oregon (Kagen et al. 1999) contained a map of predicted suitable habitat but no numerical estimates and GAP reports had not been completed for Arizona or Nevada. Consequently, alternative methods were used to estimate suitable habitat in these states as described below.

• For Arizona, we used estimates of suitable habitat provided by Arizona Game and Fish Department that were made by regional managers for game management areas under their jurisdiction. We summed these estimates to determine an estimate of all suitable mountain lion habitat in Arizona under the jurisdiction of Arizona Game and Fish Department. However, this Figure does not reflect the total amount of habitat in the state as it does not include lands under the jurisdiction of the National Park Service or tribal governments.
• For Nevada, we derived a an estimate of suitable habitat by overlaying a mountain lion habitat map created by Ashman et al. (1983) and a map of management areas provided by Nevada Division of Wildlife onto a 1 - cm by 1 - cm grid and estimating the percent of suitable habitat within each management area. We then summed these estimates to create a state wide estimate. Because our total estimate for the state was only slightly more than the 50 thousand square miles of suitable habitat estimated by Nevada Division of Wildlife (Woolstenhulme 2005) we use our estimate herein.
• For Oregon, we considered maps of mountain lion habitat produced by GAP (Kagan et al. 1999) and the Atlas of Oregon Wildlife (O'Neil et al. 2001) as well as unpublished data provided by the Oregon Department of Fish and Wildlife. The GAP and the Atlas of Oregon Wildlife maps estimated that roughly 17 and 50 percent of the state is suitable habitat, respectively. Alternately, ODFW estimates that 96 percent of the state contains suitable habitat. The reason for the large disparity between these estimates is unclear. To maintain relative consistency in methodology among states we chose to use the estimate based on the Atlas of Oregon Wildlife map, which was published subsequent to and based upon the Oregon GAP project.

Next, to estimate the amount of suitable habitat in individual mountain lion management units, we used the following procedures:

• For California, Colorado, New Mexico, Utah and Washington we used estimates provided by state agencies derived from GAP data (UT, WA) or were modified from GAP data (CA, CO, NM).
• For Idaho, Nevada, and Oregon, where state agencies were unable to provide suitable habitat estimates at the management unit scale, we developed an estimate by overlaying a statewide map of management units and a map of mountain lion habitat generated by GAP (Idaho) or other studies (Nevada, Oregon see above) onto a 1 - cm by 1 - cm grid and counted the number of cells in each management area. We then counted the number of cells that indicated suitable mountain lion habitat and determined the percentage of suitable mountain lion habitat within each management area. Finally, we multiplied the total area in square miles of each management area as provided by state agencies by the percentage of suitable habitat in that area to derive an estimate of suitable mountain lion habitat for each management area.
• For Wyoming, we used estimates of suitable habitat as derived by Wyoming Game and Fish (Wyoming Game and Fish Department 2006). For those management areas where this information was not available from WGDF, we used the same technique as described for Idaho, Nevada and Oregon above based on GAP.
• For Montana, where Montana Fish Wildlife and Parks was unable to provide either estimates of suitable mountain lion habitat or total area of management units, we overlaid a map of management regions and map of suitable habitat generated by GAP onto a 1 - cm by 1 - cm grid and counted the total number of cells in the state and in each region and the total number of cells in each region indicating suitable habitat. To estimate the total area of each region in square miles we divided the number of cells in each area by the number of cells statewide and then multiplied this number by the land area of the entire state according to the 2000 U.S. Census. Finally, to estimate the amount of suitable habitat in each area we multiplied the total estimated area of each area by the percentage of cells in the area indicating suitable mountain lion habitat and rounded the result to the nearest 1000 square miles.

Conclusions and Recommendations

The global loss of biodiversity poses one of the greatest challenges facing human society. Large carnivores are considered a pivotal tool in the effort to conserve biodiversity because of their ability to maintain the health and integrity of ecosystems (Terborgh et al. 1999, Ray et al. 2005). According to Ray et al. (2005), "keeping large carnivores is a measure of how we are doing in the battle to save the planet's biodiversity."

In the western United States, the mountain lion is the only remaining large carnivore with viable populations throughout the region (Logan and Sweanor 2001). Consequently, conserving mountain lions in viable and ecologically effective populations can strongly benefit efforts to conserve native biodiversity.

However, heavy and sustained exploitation of mountain lions by humans has resulted in lion population declines in at least four of the eleven western states (i.e., Idaho, Montana, Utah and Washington). These population declines raise questions about the impacts of current management practices on the long - term viability of mountain lion populations and thus on biodiversity. Unfortunately, there is a striking lack of research aimed at understanding the short term and cumulative effects of exploitation on mountain lion populations or on ecosystem health.

Effectively conserving self - sustaining and ecologically effective populations of mountain lions in the American West will require actively addressing issues related to exploitation and habitat loss. More specifically, however, it will require that wildlife agencies change their management focus from a single - species, utilitarian approach to an ecosystem management approach that considers mountain lions in their ecological context rather than simply as resources for hunters or problems for ranchers, landowners and the general public.

Critically, we must pursue strategies for conservation and management that satisfy the common good  -  such as maintaining ecological health, conserving biodiversity, and representing the full array of human values towards this species  -  rather than merely satisfying the needs of special interests.

To this end, the Mountain Lion Foundation makes the following recommendations:

• Manage mountain lions in the context of their important ecological role in maintaining and restoring ecosystem health. Base management policies and approaches in the principles of conservation biology (Torres et al. 2004).
• Scientifically demonstrate that current management practices are maintaining sustainable and ecologically effective populations of mountain lions.
• Create protected areas and linkages for mountain lions to promote the long - term viability of mountain lion populations.
• Standardize recording and compilation of mountain lion mortalities so that reporting is consistent within and across states.
• Standardize criteria and protocols for the issuance of depredation permits and public safety removals of mountain lions so that these are consistent within and across states.
• Support and initiate research to determine when and where mountain lions play ecologically significant roles and what densities of mountain lions are needed to generate these effects (Ray et al. 2005), and how exploitation of mountain lion populations affects the species' ecological role.
• Implement the following management principles and other recommendations of the Cougar Management Guidelines (CMGWG 2005: 8 - 10), which include:
  • "A large - landscape approach, on the order of thousands of square kilometers of well - connected habitat with thriving natural prey populations, is necessary for healthy, self - sustaining cougar populations."
  • "Given uncertainties about basic demographic parameters [of mountain lion populations], responses of populations to management prescriptions or hunter selectivity, temporal and spatial variation, and understanding that cougar habitat is changing, cougar management should adopt an adaptive management approach."
    • Adaptive management is "A type of natural resource management in which decisions are made as part of an ongoing science - based process. Adaptive management involves testing, monitoring, and evaluating applied strategies, and incorporating new knowledge into management approaches that are based on scientific findings and the needs of society. Results are used to modify management policy, strategies, and practices" (water.usgs.gov/owq/cleanwater/ufp/glossary.html)
  • "Cougar management should reflect the full array of human values and input from all stakeholders."
  • "In light of the diversity of stakeholders and human values, funding for cougar research, management, and conservation should not be derived solely from hunting - related programs."

Acknowledgements

The Mountain Lion Foundation greatly appreciates the Summerlee Foundation for its generous financial support for this report. We also thank members of the Mountain Lion Foundation for their ongoing support.

Thanks to the following state wildlife agency personnel for providing mortality data and other information: Jerry Apker (Colorado Division of Wildlife), Dan Bjornlie (Wyoming Fish and Game), Summer Crea and Steve Nadeau (Idaho Fish and Game), Rich DeSimone (Montana Fish, Wildlife and Parks), Craig McClaughlin and Kevin Bunnell (Utah Division of Wildlife Resources), Rocky Spencer and Rich Beausoleil (Washington Department of Fish and Wildlife), Doug Updike and Steve Torres (California Department of Fish and Game), and Mark Zornes and Pat Barber (Arizona Department of Game and Fish), Russell Woolstenhulme (Nevada Division of Wildlife), Donald Whittaker (Oregon Fish and Wildlife), and Rick Winslow (New Mexico Game and Fish).

MLF intern Sarrika Attoe assisted with data collection and density estimates and MLF staff members Lynn Sadler, Tim Dunbar, Emily Cunnison and Karen Cotton provided comments on the manuscript. We are also indebted to Rick Hopkins, Ken Logan, Rocky Spencer, Rich DeSimone, Linda Sweanor, Steve Torres, Camilla Fox and others for sharing their insight into the management and conservation of mountain lions.

Endnotes

1. For states that reported mortalities by harvest year (which overlap calendar years) we report by the year in which the season began (e.g., 1998 - 1999 listed as 1998) to facilitate inter - state comparisons. States reporting lion mortalities by calendar year included Arizona, California, Idaho, Oregon and states reporting mortalities by harvest year included Colorado, Montana, Nevada, New Mexico, Utah, Wyoming, and Washington. 
2. The terminology used for management areas varies from state to state. Arizona reports mortality data by game management unit (GMU). Where GMUs had subunits we pooled data into the GMU to simplify analysis. California reports kill data by county. Colorado and Idaho report kill data by Data Analysis Unit (DAU) which are comprised of several game management units. Montana reports mortalities by GMU and Management Region; we used Regions. New Mexico reports data by Management Zone, which are comprised of several GMUs. Nevada, Utah and Wyoming report data by Hunt Areas. Oregon reports data by Management Zone, which are comprised of a number of GMUs. Washington reports kill data by Cougar Management Units, each of which contain several GMUs. We will simplify the terminology and reference areas as management units. 

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