1. Executive Summary
2. Introduction
3. Results
4. Discussion
5. Conclusions
6. Methodology
7. Acknowledgements
8. Literature Cited
9. Printable Version

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.

	Mountain Lions Reported Killed (1997-2004)
	Total	Sport Hunting	Depredation	Public Safety	Other
Arizona	2569	2136	404	5	24
California	996	N/A	918	78	N/D
Colorado	3276	2998	98	N/D	180
Idaho	5252	5090	62	7	93
Montana	4466	4321	108	37	N/D
Nevada	1649	1410	99	N/D	140
New Mexico	1472	1269	164	5	34
Oregon	2631	1441	792	210	188
Utah	3560	3216	234	N/D	110
Washington	1852	1491	152	193	16
Wyoming	1664	1504	64	N/D	96
Total	29,387	24,876	3,095	535	881

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.

	1997	1998	1999	2000	2001	2002	2003	2004	Average
Arizona	48%	46%	47%	49%	44%	42%	48%	49%	46%
California	Unavailable
Colorado	46%	48%	46%	45%	45%	42%	44%	44%	45%
Idaho	43%	42%	46%	48%	46%	48%	41%	49%	45%
Montana	44%	50%	35%	51%	52%	50%	46%	40%	46%
Nevada	46%	41%	39%	48%	45%	40%	49%	40%	43%
New Mexico	35%	38%	42%	39%	41%	40%	45%	48%	41%
Oregon	33%	42%	39%	34%	57%	43%	42%	ND	42%
Utah	32%	31%	32%	29%	40%	30%	30%	29%	32%
Washington	55%	59%	60%	59%	51%	54%	52%	49%	55%
Wyoming	37%	37%	38%	43%	37%	42%	35%	39%	38%
Average	42%	43%	42%	45%	46%	43%	43%	43%	43%

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.

Location of Research	Population Density (lions / 100 sq mi)		Source
	Resident Adults	Total
Arizona		0.55	Cunningham et al. (1995)
California		8.5 – 10	Hopkins (1989)
Colorado		2.8	Anderson (1992)
Idaho	2.6 – 4.4	4.4 – 9.1	Seidensticker (1973)
Montana		4.2 – 7.5	DeSimone et al. (2002)
Nevada		2.6 – 4.1	Ashman et al. (1992)
New Mexico	2.1 – 5.4	4.4 – 11	Logan and Sweanor (2001)
Utah	2.6		Lindzey et al. (1994)
Washington	1 – 1.8	2.3 – 3.9	Lambert (2003)
Wyoming	3.6 – 3.9	9.1 – 12	Logan (1986)
Wyoming	6.2 – 8.8		Anderson and Lindzey (2005)

Note: Reported population densities are from intensive radio-collaring research studies over relatively small areas and should not be interpreted as densities of statewide mountain lion populations.

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.

Rank	State	Management Unit	Suitable Habitat Sq Mi.	Total Kills (1997-2004)	Annual Kills per 1000 sq mi Suitable Habitat
					Avg	Max
1	WY	Area 15	471*	132	35.0	48.8
2	UT	Cache	589	139	29.5	61.1
3	WY	Area 23	532*	120	28.2	33.9
4	ID	Elk City	1,839	405	27.5	41.3
5	ID	Palouse-Dworshak	2,286	494	27	51.2
6	UT	Morgan/Rich	346	74	26.7	46.2
7	WA	Blue Mountains	613	102	26.1	55.5
8	UT	Manti	2,347	488	26.0	25.6
9	WY	Area 21	500*	103	25.8	40.0
10	UT	East Canyon	391	79	25.2	40.9
11	UT	Ogden	383	67	21.9	20.9
12	WY	Area 18	477*	76	19.9	25.2
13	UT	Chalk Creek & Kamas	567	87	19.2	21.2
14	WY	Area 6 & 27	958*	145	18.9	32.4
15	UT	Wasatch Mtns.	1,982	298	18.8	23.7
16	UT	Fillmore	1,333	196	18.4	30.8
17	AZ	GMU 31	1,223	117	18.1	23.7
18	AZ	GMU 27	1,347	191	17.7	24.5
19	ID	Panhandle	7,390	1,100	17.7	23.8
20	NM	B	866	117	16.9	25.4
22	UT	Zion	850	114	16.8	28.2
23	AZ	GMU 17	978	130	16.6	19.4
24	WY	Area 7	844*	112	16.6	30.8
25	ID	Hells Canyon	1,320	182	16.4	21.6
26	WY	Area 26	680*	88	16.2	35.3
27	NV	Area 12	345	55	16	26.1
28	MT	Region 2	7,657	1,280	15.6	29.0
29	MT	Region 1	9,037	1,402	15.4	22.8
30	ID	Lolo	2,374	292	15.4	26.5

Note: * indicates Wyoming management units where estimates of suitable habitat are of winter core range (Wyoming Game and Fish 2006), and kill densities therefore are higher than if all suitable habitat were included

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.

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