Avoiding the animals that will hunt you and your fawns is an integral part of how you move across the landscape. Cougars, padding on giant, soundless paws, are to be especially feared, as you are their favorite meal. As such, cougars directly impact where you go to find food, water and rest, and when you do it, according to\u00a0a new study in the journal\u00a0Current Biology<\/em>.\u00a0<\/em><\/p>\n The study reinforces the idea that the presence of cougars, also known as pumas, mountain lions and some 40 other names in English, alters how their prey uses the landscape. In doing so, they keep humans safer by pushing the region\u2019s black-tailed deer (Odocoileus hemionus columbianus<\/em>) away from roads and potential collisions with vehicles.<\/p>\n Nationwide, there are 1.6-2.1 million accidents involving deer every year in the U.S.,\u00a0killing 200-440 people\u00a0and\u00a0costing about $10 billion a year, according to data cited in a\u00a02025 study.<\/p>\n The cats aren\u2019t patrolling the highways and chasing deer away from traffic, of course.<\/p>\n \u201cThe deer know where they\u2019re most likely to be at risk of\u00a0an encounter with a large carnivore, and they avoid these areas more \u2014 and they shift their activity to minimize those risks,\u201d says Mark Elbroch, director of the puma program at the New York City-based nonprofit\u00a0Panthera\u00a0and a co-author of the new study, which was a collaboration between Panthera and\u00a0Conservation Science Partners, a U.S.-based research nonprofit. The tasty, new vegetation growing near developed areas and roads is less appealing if there are pumas there, he says. \u201cThey scare the deer away.\u201d<\/p>\n Ecologists, including Elbroch, sometimes call this a \u201clandscape of fear.\u201d Prey learn where predators are most likely to hunt and avoid risky areas or habitat altogether or use those areas at a potentially safer time of day. In both cases, the changes deer make to stay away from cougars also keep them away from an even bigger killer of deer \u2014 vehicles.<\/p>\n \u201cThe impact was dramatic,\u201d Elbroch says. \u201cWe had a 76% reduction in the expected number of deer-vehicle collisions [on Washington\u2019s Olympic Peninsula] with the presence of cats versus low activity of cats.\u201d<\/p>\n Elbroch and his research team analyzed data from 503 camera locations alongside GPS data from 59 collared pumas from\u00a0Panthera\u2019s\u00a0Olympic Cougar Project, a long-term effort to track the cat\u2019s movement in the region.<\/p>\n They combined the camera trap images with data on how deer and Roosevelt elk (Cervus canadensis roosevelti<\/em>) used the landscape \u2014 and how that overlapped with nearly 1,000 reported wildlife-vehicle collisions between July 2020 and June 2025. Deer accounted for 92% of those collisions, with deer and elk together responsible for 97%.<\/p>\n Where pumas were present, deer were 15% less likely to occupy areas with a high density of roadways. They were also much more likely, 86% more likely, to reside in remote areas, far from development.<\/p>\n Their daily schedules also changed: Deer shifted to daylight hours, becoming less active at night. Pumas are crepuscular and nocturnal, most active at dawn and dusk and under cover of darkness, which is often when they\u2019re out hunting.<\/p>\n At first glance, that might seem like bad news. More deer moving around during daylight means more deer moving around when humans are driving.<\/p>\n But Glen Kalisz, a habitat connectivity biologist with Washington\u2019s transportation agency, points out that nighttime collisions are harder to avoid. Visibility is worse and people often drive faster with less traffic on the road, so reaction times may be slower, and deer caught in headlights may freeze rather than flee.<\/p>\n Kalisz works on reducing wildlife collisions across the state, primarily by creating wildlife crossings and erecting fencing to guide animals to underpasses or overpasses, \u00a0keeping them off roadways. He says the new research fits within a broader lesson: Wildlife behavior can have enormous consequences for where and when collisions occur.<\/p>\n Overall, in areas with the most pumas, the probability of a deer-vehicle collision fell by 67%, the study finds.<\/p>\n And though many people fear predators, \u201cdeer are the more dangerous species,\u201d Kalisz says. Cougars rarely kill people in the U.S. \u00a0Only 29 deaths have been attributed to cougars since 1868 \u2014 158 years \u2014 while up to 440 people die in vehicle collisions with deer annually.<\/p>\n On the Olympic Peninsula, wildlife-vehicle collisions caused two human deaths and more than 80 injuries during the study period, from 2020-2025. The researchers estimated that the associated vehicle repair and health costs at $14.7 million.<\/p>\n The team\u2019s research is fascinating because it\u2019s counterintuitive. The reduction in car-deer accidents appears to be driven primarily by deer behavior, not simply by pumas eating more deer and reducing their population. A cougar can only eat about 48 deer a year, which wouldn\u2019t reduce their population enough to affect road safety. Keeping a whole herd of deer away from roads is what leads to greater driver safety.<\/p>\n \u201cWe know the deer want to be there, and we know the cats are looking for deer,\u201d Elbroch says. \u201cYou throw a highway through it,\u201d and the ancient predator-prey relationship suddenly intersects with a very modern hazard.<\/p>\n Kalisz sees some limitations in this study. Most notably, the researchers had to use the percentage of developed land as a proxy for traffic volume, as detailed traffic data wasn\u2019t available across the entire study area.<\/p>\n That proxy isn\u2019t always an accurate way to understand the landscape in the Olympic Peninsula, an area that includes large areas of clear-cuts and active logging operations (and associated heavy-duty vehicle and employee traffic), as well as an influx of seasonal visitors to homes in forested areas \u2014 meaning that traffic volumes in local areas might be higher or lower than expected, given the population density.<\/p>\n Kalisz says traffic volume and collision rates have a complicated, nonlinear relationship. More collisions can occur on moderately busy roads, where animals may be more inclined to chance a crossing, versus a heavily trafficked thoroughfare.<\/p>\n \u201cOnce you get to like 10,000 vehicles or above, that\u2019s usually considered a complete barrier to animal movements, and at that point, the noise and the light create so much disturbance that animals don\u2019t even attempt to cross the road, so they\u2019re not getting hit,\u201d he says.<\/p>\n He also notes that WSDOT, the state transportation agency, has another potentially useful dataset: carcass removals. Collision reports generally require significant vehicle damage or human injury, meaning many less-serious strikes that kill a deer may never make it into official reports. \u201cBecause of those two limiting factors, WSDOT records about five times more carcass removals than collision reports,\u201d Kalisz says.<\/p>\n Those caveats don\u2019t erase the study\u2019s central finding, he says, but likely support it. The study points towards the next questions researchers could ask following these surprising findings on deer behavior.<\/p>\n A big one is how other animals may or may not be affected by similar variables: Even though deer are the majority of animals killed by car strikes, cougars eat a wide variety of prey species that are involved in car crashes. \u201cWe occasionally see moose, elk, bighorn sheep and beavers, which can get up to 60 pounds [27 kilograms]\u00a0and cause collision risks,\u201d Kalisz says.<\/p>\n Another question prompted by the study is whether cougars might indirectly be protecting humans in other ways, particularly from disease. As of\u00a02024, chronic wasting disease\u00a0(CWD), a fatal neurological illness for deer and other cervids, was present in Washington State.<\/p>\n Unlike human hunters,\u00a0research has found\u00a0that mountain lions selectively remove weaker animals sick with diseases including CWD. The disease is similar to\u00a0bovine spongiform encephalopathy,\u00a0or mad cow disease, and has not infected humans, though experts advise caution when handling venison. \u201cSo cougars could be helping reduce the spread of that,\u201d Kalisz says.<\/p>\n The newly published research points to the idea that predators provide more than the ecological benefits we immediately see. They influence ecosystems by keeping quickly-reproducing species in check, feeding scavengers and redistributing nutrients.<\/p>\n But it seems that they also reshape the behavior of living animals in ways that benefit human safety. With eastern U.S. states considering the reintroduction of cougars, this data might serve as a science-based counterpoint to human fears. The animals\u2019 original home range included almost the entirety of North America; and its been determined that\u00a0this won\u2019t recolonize the east without help from humans.<\/p>\n The nonprofit\u00a0Mighty Earth\u00a0has launched efforts in Vermont to bring the cat back to its former territory there, calling the campaign \u201ccatamount conversations.\u201d Panthera has identified more than a dozen landscapes east of the Mississippi that cougars could call home and, in doing so, potentially keep drivers safer.<\/p>\n Suraci,\u00a0J.\u00a0P., Lacey,\u00a0L.\u00a0M., Parsons,\u00a0A.\u00a0W., Cendejas-Zarelli,\u00a0S., Stratton,\u00a0A., Sager-Fradkin,\u00a0K., \u2026 Elbroch,\u00a0L.\u00a0M. (2026). Large carnivores shape road safety through effects on prey space use.\u00a0Current Biology<\/em>. doi:10.1016\/j.cub.2026.06.072<\/a><\/p>\n Sharma,\u00a0S., Guynn,\u00a0S.\u00a0T., Khanal,\u00a0C., & Khanal,\u00a0P. (2025). Understanding the drivers of deer-vehicle collisions in South Carolina, U.S.A.\u00a0Global Ecology and Conservation<\/em>,\u00a062<\/em>, e03857. doi:10.1016\/j.gecco.2025.e03857<\/a><\/p>\n![\"This](\"https:\/\/imgs.mongabay.com\/wp-content\/uploads\/sites\/20\/2026\/08\/18174241\/2.-Olympic-Range.jpg\" "\\"\\"")
When a landscape of fear is a good thing<\/strong><\/h2>\n
The danger of deer<\/strong><\/h2>\n
What\u2019s next for the cougars, deer \u2014 and drivers?<\/strong><\/h2>\n
Citations:<\/strong><\/h2>\n