In June 1989, a lone gray wolf in Katmai National Park was seen traveling with two brown bears, crossing the Brooks River beside them, and sitting within three feet eating the salmon scraps they left behind. The bears ate the brains and skin. The wolf took everything else. Nobody chased anyone. Nobody growled. The three animals moved through the landscape together as if they had agreed on an arrangement that all of them understood.
Bears, Wolves And Ecology
Monday, August 10, 2026
A wolf and two brown bears eating salmon together
Thursday, August 6, 2026
Pumas make roads safer for drivers
Cell Press
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Puma crossing the road in the Olympic Peninsula, Washington.
view moreCredit: Nicolás Lagos, Panthera
Living amongst large predatory carnivores could actually make you safer. A study publishing in the Cell Press journal Current Biology on August 5 found that pumas—wild cats also known as mountain lions, cougars, or panthers—change deer behavior, leading to fewer collisions with cars on roadways. In areas where puma occupancy is high, the authors report a significant reduction in the total expected number of collisions over a 5-year period.
“We found that large carnivores can make roadways safer through their effects on prey behavior and space use,” says lead author Justin Suraci of Conservation Science Partners in Truckee, California.
“Deer alter their use of both space and time where pumas are present, overlapping less with roads and reducing activity at night, when some of the most dangerous collisions occur," says Suraci. "Increased road safety thus represents an ecosystem service that large predators like pumas can provide to human communities."
The researchers were interested in quantifying these ecosystem services. While it has been suggested that predators of deer and other ungulates might cut down on car accidents, those dynamics had not been clearly shown or quantified in places where large carnivore populations are well established. Suraci and his colleagues studied a large camera trap dataset and spatial data on collisions between vehicles and wildlife to explore pumas’ effects on their prey’s behavior and the implications for human drivers across the Olympic Peninsula of Washington, USA.
“It’s important to remember that large carnivores, like many wildlife species, can only persist if they’re able to share landscapes with people, which in many cases may require us to change our behaviors and attitudes to make coexistence possible,” Suraci says.
The researchers found that, where pumas are present, deer are more active during the day. They were also 15% less likely to be in areas with lots of roads, choosing instead to spend more time in remote habitat areas.
As a result of those changes in deer activity, the researchers calculated a 67% reduction in the likelihood of a deer-vehicle collision. They also estimated a 76% reduction in the expected number of collisions between vehicles and deer over 5 years. Tracking collar data showed an increase in car accidents with deer during the day instead of at night, when those accidents tend to have worse outcomes.
“Deer try to avoid risk from pumas and, in doing so, spend less time near roads and are involved in fewer collisions,” says Suraci. “Carnivores may well be providing a similar road safety service elsewhere around the globe where populations have persisted and this valuable ecosystem service has just gone unnoticed to date.”
By shedding light on these dynamics, the researchers hope that more people may begin to realize the benefits of living among large carnivores. “This may be especially true for the eastern US and Canada, where pumas are slowly, naturally recolonizing, and there are ongoing discussions about a potential reintroduction program,” says Mark Elbroch of Panthera in New York City.
“While wildlife have inherent value outside of the benefits they provide to humans, a clear articulation of those benefits, such as increased road safety as a byproduct of natural predator-prey interactions, can, I believe, provide a very valuable tool to help increase tolerance for predatory wildlife and encourage the behavioral changes that coexistence requires.”
"When we talk about pumas, we often focus on the risks they pose. But we rarely stop to consider the many ways they benefit us as well,” Elbroch says. “Living alongside large carnivores isn't simply about protecting wildlife; it's about protecting the many ways they quietly benefit us every day."
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This work was supported by the Administration for Native Americans, the USFWS Tribal Wildlife Grant program, Ayers Wild Cat Conservation Trust, and the Fat Cat Feline Fund.
Current Biology, Suraci et al., “Large carnivores shape road safety through effects on prey space use” https://www.cell.com/current-biology/fulltext/S0960-9822(26)00818-3
Saturday, July 11, 2026
Beavers thrive in river estuaries along North America’s northwest coast
High-density beaver dams may have important ecological role beyond their traditional habitat
Peer-Reviewed PublicationPLOS
image:
Beaver dam and pond in the Snohomish Estuary’s Quilceda marsh (48.05° N, 122.19° W). Note shrubs and spruce trees in background, tidal sedge (Carex lyngbyei) in the foreground. A log has drifted in on a higher high tide and has come to rest on the side of the beaver dam. The pond is waist to chest deep with an accumulation of soft, unconsolidated sediments. During higher high tides water reaches the marsh surface. Photo by the author (Figure S1).
view moreCredit: W. Gregory Hood., 2026, PLOS One, CC-BY 4.0 (https://creativecommons.org/licenses/by/4.0/)
Beavers are widespread in estuaries and tidal wetlands in the Pacific Northwest of the United States, demonstrating that they are not restricted to rivers and streams, Gregory Hood at the Skagit River System Cooperative, USA, reports on July 8, 2026 in the open access journal PLOS One.
Beavers are famous for their construction skills, building domed lodges and damming rivers with logs. The ponds that their dams create can provide important habitat for plants, birds and fish, and their ability to alter ecosystems has given them the title of ‘ecosystem engineers’. Beavers can also be found in estuaries, where the twice-daily ebb of the tides causes water fluctuations and brings in saltwater from the ocean. However, little is known about beaver ecology and behavior in these tidal habitats.
Researchers surveyed North American beaver (Castor canadensis) lodges and dams in tidal wetlands in British Columbia, Washington, and Oregon to understand how beavers use river deltas and estuaries. They found that beavers were widespread in these tidal habitats, with an average of 19 dams and 2 lodges per kilometre in surveyed channels of the Snohomish and Skagit rivers. This is more than twice the density of beaver dams that has been previously reported for non-tidal river channels. Detailed measurements of beaver structures revealed that dams in tidal habitats tend to be shorter than those in rivers, meaning that they would usually be flooded at high tide. This suggests that their main function is to trap water at low tides, allowing beavers to move freely through the river system. They may also help to block saltwater brought in by the tide. The researchers inspected historic aerial photos on Google Earth dating back to 1990 and found that an estuarine beaver dam can remain in place for at least 35 years, spanning multiple generations of beaver.
The study expands the known habitat distribution of beavers and demonstrates that these charismatic creatures can thrive in river estuaries. The density of dams also suggests that they may have a significant ecological impact in these habitats. By creating deep pools of water at low tide, their dams may provide important habitat for threatened species, such as Chinook and coho salmon. But more research is needed to understand how conservationists can work with beavers to restore river estuaries in the Pacific Northwest, the authors say.
The author adds: “The conventional view of beaver is that they live exclusively in rivers and lakes. My work shows that beaver are much more adaptable than this. They are also broadly distributed and resident in tidal marshes and swamps of the Pacific Northwest, from at least British Columbia to southern Oregon. So, it would not be surprising if beaver were found in tidal habitats in other regions of North America or Eurasia.”
“Now that we know that beaver can be commonly found in tidal wetlands, we also know that there are new questions to ask about beaver ecology in these systems. We have a lot to learn about tidal beaver ecology and how it compares to more conventional river and lake beaver.”
“Knowing that beaver are commonly found in tidal marshes and swamps leads to the realization that we need to account for the ecosystem effects of beaver in these systems. Beaver are ecosystem engineers in rivers and lakes, i.e., their dam-building activities have broad effects on other flora and fauna in those ecosystems. So, they are likely to also be ecosystem engineers in tidal ecosystems. Without accounting for beaver in tidal ecosystems our understanding and management of these systems is likely to be incomplete and flawed.”
The freely available article in PLOS One: https://plos.io/3R9H1Xp
California wolves feed heavily on cattle
Two new studies examining gray wolves in California paint a complex picture of life on California’s ranching landscapes: wolves eat cattle more than anything else and the presence of the predators causes significant stress among livestock.
In the first study, University of California, Davis, researchers found wolves from the Lassen and Harvey packs in northeastern California were primarily eating cattle. They collected scat samples during the summer months of 2022 and 2023 and found 72% of wolf scat contained cattle DNA. The research was published in PLOS One.
“Whether it's through scavenging or whether it's through depredation, it’s a huge component of the wolves’ diet,” said lead author Tina Saitone, a professor of Cooperative Extension in the UC Davis Agricultural and Resource Economics Department. “Their conservation success is because of livestock producers in the state.”
Cattle appeared as the most frequently occurring food item during both summers of the study, present in 86% of samples in 2022 and 55% in 2023. While all 2022 samples were from the Lassen Pack, the 2023 samples included eight from the newly established Harvey Pack.
Wolves are a state and federally recognized endangered species. The first confirmed wolf entered California in 2011, following a nearly 100-year absence. The California Department of Fish and Wildlife estimates the state is now home to nine wolf packs.
Few natural prey
Wolves in California live in landscapes shaped by people. They have fewer wild ungulate prey options than wolves in other parts of North America. Mule deer are their only significant wild food source, but populations have dropped sharply since the 1970s.
Saitone said the scarcity of wild prey may be one reason wolves are eating cattle instead. Researchers found mule deer in just 45% of the scat samples, significantly less common than cattle.
Keeping wolves away from cattle is difficult on many of these working landscapes.
“Conservatively, we’re talking about a million acres in our study area and 10,000 cow-calf pairs,” said Saitone. “It’s not as simple as putting up an electric fence on a two-acre pasture or putting cattle in the barn at night.”
Cattle are stressed
Researchers also examined how living among wolves affects cattle. Their findings suggest the costs of wolf reintroduction extend well beyond animals lost to predation.
A second study, published in Ecology and Evolution, measured cortisol levels in tail hair samples collected from beef cattle grazing rangelands in northeastern California — some herds sharing territory with wolf packs, others in areas without wolves. Cortisol, often called the stress hormone, accumulates in hair over time, making it a reliable indicator of chronic stress rather than a momentary response to fright.
Cattle herds living among wolves had cortisol levels 58% higher than those in control herds — a significant physiological difference. This marks one of the first times hair cortisol analysis has been used to study how the reintroduction of predators reshapes livestock physiology in the field.
"What this really confirms is that death or depredation is not the only impact here," said Saitone. "Living among wolves for cattle is a chronically stressful experience, and that could ultimately have production-related impacts in both the short and the long term."
Could it affect reproduction?
Saitone said the findings are just a starting point. Researchers next want to understand whether elevated stress levels translate into lower conception rates. It’s a concern long raised by ranchers that has not yet been established through direct biological evidence. When breeding cows fail to conceive, it can directly affect a rancher’s bottom line.
"That's their whole purpose,” said Saitone. “These are mother cows that are supposed to be generating calves as a marketable product.”
Saturday, June 20, 2026
Mountain lions have major ecological impact even in small preserve
Stanford University
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A mountain lion photographed by a motion-activated cameras on Stanford's Jasper Ridge Biological Preserve.
view moreCredit: Image courtesy of Trevor Hébert/Stanford University.
Big cats have a big impact. A long-term study showed that when mountain lions began regular visits to a small, suburban preserve about 45 miles south of San Francisco, it changed the behavior of many other animals.
Mountain lions (Puma concolor) started appearing with increasing frequency on trail cameras at Stanford’s Jasper Ridge Biological Preserve ('Ootchamin 'Ooyakma) from 2015 to 2020. Researchers documented a corresponding drop in deer activity compared to the prior years of lower or absent puma activity. Vegetation surveys also showed that many woody plants deer like to eat or tend to trample, including young oak trees, began to thrive.
These types of multi-level effects, called trophic cascades, have been studied primarily in large wilderness areas, particularly cascades caused by apex predators such as wolves reintroduced into Yellowstone National Park. This research, published in Ecology and Evolution, indicates the effect can be found in smaller preserves as well.
“In the past, small preserves like Jasper Ridge have often been dismissed for holding very little ecological value, but this study shows that when these small preserves are connected to large wilderness like the Santa Cruz Mountains, you can still see magnificent ecological phenomena like trophic cascades,” said Chinmay Sonawane, the study’s first author and doctoral student in biology in Stanford’s School of Humanities and Sciences (H&S). “They are not just things that happen in places like Yellowstone far away from the city and people. They can happen in these places that are quite small and more urban as well.”
The ecology of fear
The researchers analyzed data frommotion-activated cameras and vegetation surveys and found two types of trophic cascades, one that connected mountain lions, deer, and vegetation, called a tri-trophic cascade, and another that involved smaller predators at Jasper Ridge. For the second, increased puma presence was associated with decreases in the activity of coyotes and bobcats, which were perhaps leaving the area or changing the time they are active to avoid the much larger pumas.
With fewer coyotes and bobcats on the landscape, foxes appear to have seized an opening and were seen more often, which then may have suppressed the activity of their primary prey: rabbits.
These patterns involving an apex predator have been called the “ecology of fear,” since the mere perception of a large predator can cause other animals to change their behavior, which then affects the other organisms that they rely on for food.
In this study, the findings at the lower level of the cascades – the indirect influence of mountain lions on vegetation, foxes, and rabbits – are considered provisional, as other influences such as changes in fog and temperature could not be ruled out.
Yet the mountain lion presence had a clear impact on deer, coyotes, and bobcats – and therefore, on the ecology of Jasper Ridge, underscoring the role both of apex predators and small preserves. In the U.S., 82% of protected areas are under 5 square kilometers (about 2 square miles), so they will likely be critical spaces for wildlife and plants as rapid urbanization continues, said Rodolfo Dirzo, study co-author and Stanford professor of biology in H&S.
“Maintaining sites where there is an entire community of animals, from predators to prey to the prey’s resource base, is very important,” he said. “When one piece is missing – and it’s typically the top predators that require larger areas and are more sensitive to human impact – we will no longer have fully functioning ecosystems.”
Mystery of mountain lion motivations
Why the mountain lions started to frequent Jasper Ridge is unknown. One theory is that the female mountain lions found the preserve to be a safe place to raise their young, as a mom with kittens has been spotted on camera during the study. Whatever the reason, they are only visitors. Mountain lions have a huge range in the Santa Cruz Mountains from 20 to 170 square kilometers (about 8 to 66 square miles). Jasper Ridge is far too small to have its own puma population.
Despite the occasional high-profile sighting of a mountain lion in San Francisco or in the suburbs, they tend to stay far away from humans, said Elizabeth Hadly, the study’s senior author and Stanford professor emerita of biology in H&S. They are also nocturnal, so they are not often on the landscape when people are active.
“Pumas are afraid of our smell and our sounds; they don’t like to see us moving,” said Hadly, who is also the former faculty director at Jasper Ridge. “Pumas use all of their senses to avoid humans.”
Humans are the No. 1 cause of mountain lion deaths, either through hunting or car accidents, Hadly pointed out.
“Clearly, we exert our own ecology of fear,” she said. “Humans are the ultimate predator on almost every landscape.”
Thursday, June 18, 2026
Florida panther vs wild hogs
In March 1987, Florida biologists released twelve radio-collared wild hogs into the Everglades to see if they could feed endangered Florida panthers by giving them something easy to kill. Bears ate two. An alligator ate one. Hunters poached three. A panther finally killed one after 117 days. By then, most of the hogs were already dead from everything except the animal they were supposed to feed.
Wednesday, June 17, 2026
Fishers vs Canada lynx