Literature Review

Blakey, R. V., J. A. Sikich, D. T. Blumstein, and S. P. D. Riley. 2022. Mountain lions avoid burned areas and increase risky behavior after wildfire in a fragmented urban landscape. Current Biology 32:4762–4768.

Study Summary

Researchers used specialized GPS collars to track 17 mountain lions in the Santa Monica Mountains and Simi Hills of Los Angeles and Ventura counties, California, to compare their behavior in the 15 months before and the 15 months after the 2018 Woolsey Fire. The lions were part of a long-term National Park Service study, and the analysis looked at use of burned and urban areas, road crossings, daytime activity, distance traveled, space use, and overlap between individuals.

After the fire, mountain lions avoided burned areas, and males avoided them more than females. Use of urban areas stayed low (a modeled probability of 4.3% before the fire and 5.4% after). Other behaviors that can increase contact with people changed more: road crossings rose from about 3 to 5 per month, and daytime activity rose from 10% to 16%. Monthly distance traveled increased from about 250 to 390 km, and overlap between animals of the same sex increased, which the authors suggest may raise the risk of conflict between mountain lions.

This was an opportunistic study with a small sample size and the design did not include an unaffected comparison group. The authors note they cannot rule out effects of rainfall and deer abundance, and that results by age and sex class should be interpreted cautiously. Because the study did not track lions for more than 15 months after the fire, it is unclear how long it takes for lions to return to burned areas as the vegetation grows back. They conclude that more road crossings and daytime movement after large fires may increase vehicle-strike and encounter risk near cities, and that wildlife crossings and habitat connectivity may be particularly important in fire-prone urban areas.

For the foothills and Northern California, this Southern California research may also help inform residents that immediately post-fire, as lions are displaced on the landscape, they may be more active in crossing roads or more likely to be in close proximity to other lions, which creates competition. This information could be applied to some other species during and post-fire, as many animals are escaping the burn area.

Bolas, E. C., A. D. Pingatore, M. Mathur, D. T. Blumstein, J. A. Sikich, J. A. Smith, J. F. Benson, S. P. D. Riley, and R. V. Blakey. 2025. Human recreation influences activity of a large carnivore in an urban landscape. Biological Conservation 301:110812.

Study Summary

Researchers studied how mountain lions in and around Santa Monica Mountains National Recreation Area, in greater Los Angeles, adjust their daily activity to hikers, runners, and cyclists. They tracked 22 mountain lions with collar data between 2011 and 2018. Collar data was then compared to recreation activity of humans built from publicly available Strava activity. They also compared weekends with weekdays.

In areas with more recreation, mountain lions were more nocturnal and spent less of the daytime active. From low- to high-recreation areas, females went from being active about 25% of the day to 17%, and males from 15% to 8%. There was weaker support for shifts in dawn activity timing and longer daytime rest periods. The researchers found no evidence that mountain lions changed their behavior on weekends. They suggest this may be because the animals were already mostly nocturnal, which may be enough to avoid most recreation.

The link between recreation and nocturnal activity was largely driven by two adult males living in the most urban parts of the study area, and the fitness costs of these behavior shifts are unknown. The authors suggest that mountain lions’ ability to shift activity in time, and to keep avoiding people, may help reduce conflict, and that identifying places and times that serve as refuges for mountain lions could help managers of heavily used natural areas.

While the study could be lacking in data on human activity due to not everyone publicly tracking their activity, it says a lot that there was a connection found between the data that were collected and collar data. This study helps reflect that even in high-pressure usage situations, like the Santa Monica Mountains, mountain lions as previously described will generally avoid people and where possible change their usage and activity to avoid people and are highly adaptable to their environment and people.

California Department of Fish and Wildlife. 2025. Black bear conservation and management plan for California. California Department of Fish and Wildlife, Sacramento, California, USA.

Study Summary

This April 2025 plan from the California Department of Fish and Wildlife (CDFW) updates the state’s 1998 black bear management plan. It sets goals for conserving ecologically functional bear populations, providing hunting and viewing opportunities, reducing human-bear conflict, and considering animal welfare. CDFW now monitors bears in nine Bear Conservation Regions using an integrated population model that combines ages from hunter-provided teeth with survival and reproduction rates, most of which currently come from published studies elsewhere in North America. Camera-trap surveys and local density studies inform the model’s starting values.

It is estimated that the statewide average is 59,851 black bears for 2020–2024, and CDFW describes strong preliminary evidence that populations in hunted regions have been stable over the past decade. Hunters took an average of 1,219 bears per year from 2020 to 2024. The plan notes that the number of bears taken by hunters has dropped substantially since the use of dogs to hunt bears was banned starting with the 2013 season. From 2017 to 2023, 7,219 human-bear conflict reports were submitted to CDFW’s Wildlife Incident Reporting system, most involving depredation and property damage. The plan cautions that trends in reports may not reflect actual trends in conflict; for example, a rise in reports in 2021 and 2022 may partly reflect increased reporting, which CDFW considers likely to have been an important factor in 2022 after policy and staffing changes. The number of bears killed under depredation permits fell from 100 in 2017 to 16 in 2023; CDFW notes that a 2022 policy prioritizing nonlethal measures is likely influencing recent patterns. The plan names reducing bears’ access to human food as the primary tool for managing conflict. It notes that bear-resistant containers can be costly and are often not used correctly, and that it is unclear whether hunting would reduce conflict in California, where harvest rates have been low.

Estimates for regions without hunting are based on camera data and should be interpreted cautiously, and population trends cannot yet be evaluated in those regions. The plan calls for designated local study areas, an annual status report, periodic review of the plan, and continued consultation and co-management with California Native American Tribes. For communities and managers, the main practical message is to secure attractants and to use nonlethal measures before lethal removal.

Dellinger, J. A., and S. G. Torres. 2020. A retrospective look at mountain lion populations in California (1906–2018). California Fish and Wildlife 106:66–85.

Study Summary

Researchers with the California Department of Fish and Wildlife looked at how a century of changing management may have affected California’s statewide mountain lion population. Management ranged from a bounty system (1906–1963) to specially protected status under Proposition 117 in 1990. The researchers combined historical records of mountain lions killed through bounties, hunting, depredation permits, and vehicle strikes with growth and mortality rates from other studies. They then ran a population model backward from 2018 to 1906, repeating it many times and with random selections of starting populations to test the model.

All simulations indicated a statewide decline during the bounty period. Bounty hunters took an average of 224 mountain lions per year, or 12,580 in total. The authors suggest that removals in many bounty years exceeded the level the population could replace. The simulations then indicated an increase after the bounty ended, continuing until the mid-1990s and appearing to stabilize until about 2000. After 2000, results diverged depending on the starting population, so the recent trend could not be determined. The authors point to rising depredation permits after the bounty era as further support for population growth, while noting that increased human density and development may also have contributed and that more research is needed.

The authors state that their results cannot be assumed to represent precise population figures. The model did not account for habitat change, road development, prey abundance or other density-dependent factors, or differences by sex and age, and it treated all removals as additive, meaning it assumed each lion killed by people added to, rather than replaced, deaths that would have happened anyway. Poaching data were scarce, and vehicle-strike records are likely underreported. The study offers historical context for debates over the species’ protected status, but not a current population estimate. The authors conclude that California needs a substantial increase in systematic mountain lion monitoring to inform policy.

Janeiro-Otero, A., T. M. Newsome, L. M. Van Eeden, W. J. Ripple, and C. F. Dormann. 2020. Grey wolf (Canis lupus) predation on livestock in relation to prey availability. Biological Conservation 243:108433.

Study Summary

Researchers conducted a global systematic review of gray wolf diet studies to ask whether wolves choose wild prey or livestock. They also examined whether prey abundance, prey traits (such as body size and horns or antlers), and livestock husbandry affect that choice. They analyzed 119 diet studies from 27 countries, most based on scat contents and most from Europe. They estimated how much of the diet came from each prey species and compared this with prey and livestock densities, which often had to be taken from other sources.

Overall, wild prey made up a larger share of wolf diets than livestock, and wolves selected wild prey even where livestock was abundant. This pattern held in most regions. The exceptions were parts of southern Europe (such as Spain and Greece) and several regions in Asia, where wild ungulates are scarce and wolves fed mainly on livestock. Husbandry mattered: livestock left unattended and grazing freely were most vulnerable, and areas where livestock grazed freely in small numbers were more vulnerable to attacks.

The authors note that prey densities often had to be estimated from other sources, including municipal livestock statistics, which may under- or overestimate numbers at study sites. Missing values were statistically filled in, and data from Asia were limited. They caution that the dataset can reveal only broad patterns. They also note that increasing wild prey could increase wolf numbers and, potentially, conflict. Overall, they conclude that maintaining and restoring wild prey and protecting livestock, especially by not leaving animals unattended, could reduce wolf predation on livestock and support coexistence.

Benson, J. F., J. A. Sikich, and S. P. D. Riley. 2016. Individual and population level resource selection patterns of mountain lions preying on mule deer along an urban-wildland gradient. PLOS ONE 11(7):e0158006.

Study Summary

Researchers studied where mountain lions fed on mule deer along the urban-wildland edge of greater Los Angeles, focused on Santa Monica Mountains National Recreation Area and nearby ranges. They used GPS collars to track mountain lions from 2002 to 2015 and mapped 420 mule deer feeding sites from 26 mountain lions. They compared habitat type usage, distance to developed areas, and closeness to water at those sites with what was available across each lion's home range.

Males were more likely than females to feed in riparian woodlands and closer to water. Females fed on mule deer closer to developed areas than expected from how much developed land was in their home ranges. It's important to note that while they fed closer, no site was found within a residential developed area. Mountain lions that already had more developed areas within their home ranges chose developed areas less often than lions that had less development within their home ranges. The authors suggest this pattern reflects a trade-off: feeding near development can offer abundant deer, but high urbanization may outweigh that benefit because of human disturbance.

No mule deer study was available in the same area, so the authors could not measure how deer abundance alone shaped where kills happened or confirm that deer presence would be higher in developed areas. Feeding sites show where lions ate deer, not every place deer were at risk. The authors conclude that continued development next to Los Angeles and similar cities could reduce the quality of foraging habitat for mountain lions, and that, at least while preying on mule deer, lions in this study appear to be living in such a way to reduce possible encounters with people.

For foothill and Northern California residents living along an urban-wildland edge, this Southern California work supports the idea that mountain lions can use areas near homes when deer are nearby, yet often keep some distance from dense development when they have room to do so. Lowering attractants that draw deer close to houses remains a practical way to reduce overlap. Mountain lions will typically live and hunt where their prey are. Reducing attractants for deer could reduce likelihood of property use by mountain lions when they are hunting deer.

Allen, M. L., L. M. Elbroch, D. S. Casady, and H. U. Wittmer. 2015. Feeding and spatial ecology of mountain lions in the Mendocino National Forest, California. California Fish and Game 101:51–65.

Study Summary

Between 2010 and 2012, researchers studied mountain lions in the Mendocino National Forest in Northern California, a landscape where black-tailed deer are the main prey item. They fitted GPS collars on 7 mountain lions and investigated nearly all of the location clusters those collars flagged, so they could find kills and describe diet, hunting timing, feeding sites, home ranges, and local density.

Mountain lions killed approximately 1.07 deer per week on average, which is high compared with what other studies have found. Black-tailed deer made up almost all of the prey biomass. Of deer one year or older that were killed, most were in fair or better body condition. Fawns were killed more often during daytime hours than at night. When researchers compared kill sites with later feeding sites, feeding spots were lower in elevation, flatter, and under denser canopy. Individual home ranges ranged from about 39 to 237 square miles, and the estimated density including known kittens was low at about 1.8 mountain lions per 100 square miles (roughly one lion for every 57 square miles).

The sample was small, and the authors note that intensive field methods, smaller deer body size, or scavenging by black bears could help explain the high kill rates. They found no kills of tule elk or wild pigs and caution that managers should not count on mountain lions to slow the spread of pigs. Reasons for the low lion density remain unclear; the authors discuss illegal killing and competition with bears as possible factors. They conclude that high deer kill rates together with low mountain lion density could matter for future deer dynamics in the forest.

For Northern California foothill communities near the Mendocino National Forest and similar areas, this study shows mountain lions focusing heavily on deer while showing individual differences in diet and large home ranges. Expecting lions to solve pig problems, or assuming high lion numbers wherever deer are plentiful, does not match what these researchers found. This study highlights that the relationship between deer, bears, and lions, is complicated and worth further investigation.

Grigione, M. M., P. Beier, R. A. Hopkins, D. Neal, W. D. Padley, C. M. Schonewald, and M. L. Johnson. 2002. Ecological and allometric determinants of home-range size for mountain lions (Puma concolor). Animal Conservation 5:317–324.

Study Summary

Researchers pooled radio-collar data on 57 mountain lions from three California regions—the Diablo Range, the Santa Ana Mountains, and the central Sierra Nevada—collected between 1983 and 1993. They measured seasonal home-range size and asked how sex, age, body mass, relative deer abundance, habitat type, and season shaped those ranges in coastal chaparral–oak country versus high-elevation Sierra forests with migratory deer.

Season mattered differently by region. In the Sierra Nevada, where mule deer migrate, home ranges were larger in summer and smaller in winter when deer concentrated at lower elevations. In the Coastal Ranges, home ranges tended to be smaller in summer and larger in winter. Across sites, males used larger home ranges than females. In the Coastal Ranges combined, females averaged about 35 square miles in summer and 39 square miles in winter, while males averaged about 116 and 135 square miles. Sierra averages were much larger, for example about 209 square miles for females and 279 square miles for males in summer.

Home-range estimates used older radio-telemetry methods and required a minimum of 30 locations per season, and deer abundance was not a complete measurement and showed weak ties within the study anyways. The authors conclude that habitat conservation for mountain lions should consider species-specific factors, such as sex and body mass, and landscape factors, and should assess home-range needs conservatively so important areas are not left out.

For California residents and planners, this older statewide look still underscores that a mountain lion's space needs are not one size fits all. Lions in migratory deer country may need much larger summer ranges than lions in coastal foothills, and males typically need more room than females. Planning that assumes a single small home-range size may underestimate what connected habitat must provide. This data also gives us a snapshot into the history of how lions are affected by change and development. Studies today should evaluate home-range on the same factors and take into account human population and development within the study area to compare datasets from before to now which would also give managers a better understanding of mitigation of conflict between lions and residents.

Treves, A., and F. J. Santiago-Ávila. 2020. Myths and assumptions about human-wildlife conflict and coexistence. Conservation Biology 34:811–818.

Study Summary

In this essay, researchers review how the field of human-wildlife conflict and coexistence grew from concern about wildlife threats to people toward protecting valued species and, more recently, toward fair coexistence between people and wild animals. They argue that progress depends on testing common assumptions that still shape research and practice, rather than treating those assumptions as facts.

They focus on four assumptions: that scientists are neutral and objective about conflict. That participatory, consensus-based decisions are a fair way to solve conflict problems. That wildlife threats to human interests are getting worse, and that wildlife damage adds on top of other losses rather than sometimes replacing them. They argue that some of these claims have been weakly tested or look doubtful, yet they still guide how conflict is described and managed. Two of the assumptions, they suggest, may function more like myths if they cannot be cleanly tested.

The authors call for stronger standards of evidence, tests of favored ideas against real alternatives, and fairer decision processes before wildlife policies are set. They conclude that exposing and testing these assumptions should lead to more evidence-based tools and fairer coexistence strategies.

For foothill communities, a practical takeaway is to treat claims that local conflict is "getting worse," or that every livestock loss is caused only by predators, as questions that need local evidence rather than as automatic starting points.

Bergstrom, B. J. 2017. Carnivore conservation: shifting the paradigm from control to coexistence. Journal of Mammalogy 98:1–6.

Study Summary

This overview introduces a Journal of Mammalogy special feature on shifting carnivore conservation from control toward coexistence. Drawing on a 2013 American Society of Mammalogists meeting and a long Society history of questioning lethal predator control in the western United States, the author summarizes ecological, social, ethical, and legal arguments for preferring nonlethal responses to livestock conflict with large carnivores.

He notes that most large carnivores worldwide have lost range and numbers, and that human-caused deaths from hunting, illegal killing, and roads can be large and sometimes underestimated. He argues that removing apex predators can disrupt ecosystems, that some lethal tools are not individual selective enough and other species may be caught, and that lethal control often fails to reduce livestock losses or boost game over the long term. He points to growing evidence that nonlethal tools can work and that heavily hunted carnivore populations may kill livestock more, not less, when their social structure is disrupted.

The author concludes that wildlife goals should aim to keep carnivore mortality at most at sustainable levels and to cut human-caused deaths where possible, and that lethal control of native large carnivores will face rising scientific and public scrutiny.

For California foothill residents living with mountain lions and bears, the essay's core message is that nonlethal steps to protect livestock and secure attractants deserve serious attention alongside any discussion of killing carnivores. The author is not suggesting to remove lethal control as an option entirely, but is suggesting that perhaps other causes of mortality may be compounding already depressed populations of carnivores and that further lethal control could cause more issues, not solve them. This is always a balancing act between using well supported non-lethal methods to protect livestock, along with understanding what is a sustainable harvest for carnivores where available.