Humans drove wolves to extinction in Washington state around the 1930s. Thanks to conservation efforts, by about 80 years later, wolves had returned — crossing first from the Canadian border into Washington around 2008 and later entering the state from Idaho. Since then, wolf numbers in Washington have been steadily growing, raising questions about what the return of this large predator species means for ecosystems and people alike.

In northeast Washington, where wolves have recovered most successfully, researchers from the 91̽�� and the Washington Department of Fish and Wildlife tracked one of their primary prey — white-tailed deer — in part to see what impact wolf packs are having on deer populations. The answer? So far, wolves aren’t having as much of an impact on deer as other factors.

In a published June 18 in Ecological Applications, the team reports that the biggest factors shaping white-tailed deer populations in northeast Washington are the quality of habitat available and a different, long-established large predator in the state: the cougar, also known as the mountain lion or puma. Wolves were a distant third in their impact.

“A big take-away from this study is that wolves are not returning to empty landscapes. These are places with humans and other carnivore species, like cougars, which will affect the impact that wolves can have,” said lead author , who conducted this research for her 91̽��doctoral degree as part of the . “This area has a relatively high human footprint compared to other areas where wolves have been studied. These are not national parks or dense, old-growth forests. They are areas with active logging, farming, ranching and towns. Our findings show that these factors are likely limiting the impact of wolves on one of their primary food sources.”

It’s not that wolves aren’t preying on white-tailed deer. According to the study, they are, just not enough to take a large bite out of the population as a whole.

White-tailed deer are widespread east of the Cascades. The state’s highest-density population of this species lies within the study area, which includes farmland and timber forests in parts of Stevens and Pend Oreille counties in northeast Washington. For the study, researchers radio-collared 280 white-tailed deer, 14 wolves, 50 cougars, 28 coyotes and 33 bobcats from 2016 to 2021. At the time of collaring, the researchers also noted vital statistics, including body condition, age and whether females were pregnant. When collared animals died, the team conducted a mortality investigation, if possible, and attempted to determine the cause of death.

The team, which also includes researchers with Washington State University and the Spokane Tribe of Indians, used the resulting dataset to estimate the growth rate of the white-tailed deer population over the four-year study, and to identify the major factors shaping it. The analysis determined that the white-tail population in the study area was likely stable, or slightly declining, but that wolves were not largely responsible.

The biggest factor impacting the deer population was habitat quality, including the amount of forage available for deer. For white-tailed deer, which are highly adaptable to human activity, foraging sites can range from forests and shrublands to agricultural fields. The study area includes both agricultural land and forests recently harvested for timber, both of which could provide deer with high-caloric density foraging sites, according to Ganz.

After habitat quality, the study found that predation by cougars had a smaller effect on the white-tailed population. Wolf predation had a still smaller impact. Bobcats and coyotes — both medium-sized predators — had a negligible impact on deer numbers.

“Studies like this provide valuable insights about the complexity of these systems and how managing predator and prey populations is challenging and dynamic,” said co-author Melia DeVivo, a research scientist with the WDFW. “It’s important to continue evaluating these systems to understand the impacts of management decisions. Prior to this study, one might have expected that relying solely on wolf management strategies would result in a booming deer population, when it is clearly more complex than that.”

Since their return, the number of wolves in Washington has risen steadily, reaching a minimum of 260 in 2023, according to state researchers. Four wolf packs reside in the northeast Washington Predator-Prey Project study area. The total number of wolves in the study area — about 23 — remained steady overall during the research period.

The team’s findings contrast with studies of long-established wolf populations in protected areas, like Yellowstone National Park, which show a higher impact of wolves on the population dynamics of their prey species. To the authors of this new study, those differences highlight the importance of studying wolves in a variety of habitats.

“This study reminds us that the population dynamics of predator and prey species can vary quite a bit,” said senior author , a 91̽��associate professor of environmental and forest sciences. “Habitat quality, the species that are present and the degree of human activity all affect the impact that large predators like wolves will have. It’s critical to compare different types of sites.”

The paper is part of the Washington Predator-Prey Project, a partnership between the 91̽��and the WDFW to investigate the impact of the wolves’ return on state ecosystems. Additional co-authors are , a 91̽��doctoral alum in environmental and forest sciences; Lauren Satterfield, a 91̽��doctoral student in environmental and forest sciences; biologists Brian Kertson and Benjamin Turnock with the WDFW; , a professor at WSU; Savannah Walker and Derek Abrahamson, both biologists with the Spokane Tribe of Indians; , a 91̽��associate professor of environmental and forest sciences; and , a 91̽��professor of environmental and forest sciences. The research was funded by WDFW, the National Science Foundation, the Rocky Mountain Elk Foundation, and the 91̽��College of the Environment.

For more information, contact Ganz at trganz@uw.edu.

Research on the impacts of climate change often considers its effects on people separately from impacts on ecosystems. But a new study is showing just how intertwined we are with our environment by linking our warming world to a global rise in conflicts between humans and wildlife.

The research, led by scientists at the 91̽��’s and Feb. 27 in Nature Climate Change, reveals that a warming world is increasing human-wildlife conflicts.

“We found evidence of conflicts between people and wildlife exacerbated by climate change on six continents, in five different oceans, in terrestrial systems, in marine systems, in freshwater systems – involving mammals, reptiles, birds, fish and even invertebrates,” said lead author , a 91̽��assistant professor of biology. “Although each individual case has its own array of different causes and effects, these climate-driven conflicts are really ubiquitous.”

To identify trends, the team pored over published, peer-reviewed incidents of human-wildlife conflicts and identified cases that were linked specifically to the effects of climate change. These include both short-term climate events — such as a drought — as well as longer-term changes. Warming in the Arctic, for example, is leading to loss of sea ice which has left polar bears short of food. They increasingly travel on land, sometimes entering human settlements and attacking people, as a in Alaska illustrates.

The new study shows that climate shifts can drive conflicts by altering animal habitats — like sea ice for polar bears — as well as the timing of events, wildlife behaviors and resource availability. It also showed that people are changing their behaviors and locations in response to climate change in ways that increase conflicts. Other examples of the effects of short- and long-term climate events include:

• Torrential floods in Tanzania led to more lion attacks after their usual prey migrated away from floodplains.
• Higher air temperatures in Australia triggered more aggressive behavior in eastern brown snakes, leading to more incidents of snake bites.
• Wildfires in Sumatra, Indonesia — triggered by El Nino — drove Asian elephants and tigers out of reserves and into human-inhabited areas, leading to at least one death.
• Disruption of terrestrial food webs during La Nina events in the Americas drove black bears in New Mexico and foxes in Chile into human settlements in search of food.
• Warmer air and ocean temperatures in a severe El Nino led to an increase in shark attacks in South Africa.

Most cases of human-wildlife conflict linked to climate involve a shift in resources — not just for wildlife, but also for people.

A majority of cases on land also involved a change in precipitation, which will continue to be affected by climate change. Many resulted in human deaths or injuries, as well as property damage.

In 2009, for example, a severe drought struck the western part of Tanzania’s Kilimanjaro Region. This reduced food supplies for African elephants, which in turn entered local fields to graze on crops — at times destroying 2 to 3 acres daily. Local farmers, whose livelihoods were directly threatened by the drought, at times resorted to retaliatory killings of elephants to try to mitigate these raids.

“Identifying and understanding this link between human-wildlife conflicts is not only a conservation issue,” said Abrahms. “It is also a social justice and human safety issue.”

These types of conflicts are likely to rise as climate change intensifies, particularly as mass migrations of people and wildlife increase and resources shift.

But, it doesn’t have to be all bad news.

“One major motivation in studying the link between climate change and human-wildlife conflict is finding solutions,” said Abrahms. “As we learn about specific incidents, we can identify patterns and trends — and come up with interventions to try to address or lessen these conflicts.”

Some interventions may be as simple as public-awareness campaigns, such as advising residents of the American Southwest during La Nina years to carry bear spray on a hike. Governments can also plan for times when extreme climate events will bring people and wildlife into closer contact. Botswana, for example, has funds in place to compensate herders and ranchers for drought-induced attacks by wildlife on livestock, often in exchange for pledges not to engage in retaliatory killings of wildlife.

“We have effective drought forecasts now. So, governments can engage in fiscal planning for mitigating conflicts ahead of time,” said Abrahms. “Instead of a ‘rainy day’ fund, have a ‘dry day’ fund.”

To Abrahms, one success story of note lies in the waters of the eastern Pacific. In 2014 and 2015, a record number of humpback and blue whales became ensnared in fishing lines off the California coast. Research later showed that an extreme marine heat wave had pushed whales closer to shore, following their primary food sources. California regulators now adjust the start and end of each fishing season based on climate and ocean conditions in the Pacific — delaying the season if whales and fishing gear are likely to come into close contact.

“These examples show us that once you know the root causes of a conflict, you can design interventions to help both people and wildlife,” said Abrahms. “We can change.”

Co-authors on the paper are 91̽��postdoctoral researchers T.J. Clark-Wolf, Anna Nisi and Kasim Rafiq; 91̽��doctoral students Erik Johansson and Leigh West; Neil Carter, an associate professor at the University of Michigan; Kaitlyn Gaynor, an assistant professor at the University of British Columbia; and Alex McInturff, 91̽��assistant professor of environmental and forest sciences.

For more information, contact Abrahms at abrahms@uw.edu. See a related feature story about Abrahms’ research.

Climate change will reshape ecosystems worldwide through two types of climate events: short-term, extreme events — like a heat wave — and long-term changes, like a shift in ocean currents. Ecologists call the short-term events “pulses,” and the long-term changes “presses.”

Presses and pulses will likely have different effects on animal species. But how? And how will animals respond? Answering these questions is no easy feat because individual events can have dramatically divergent impacts on an animal species. Yet understanding the effects of presses and pulses is essential as conservationists and policymakers try to preserve ecosystems and safeguard biodiversity.

Researchers at the 91̽�� have discovered how different presses and pulses impacted Magellanic penguins — a migratory marine predator — over nearly four decades at their historically largest breeding site in Punta Tombo, Argentina. In a paper published the week of Jan. 9 in the Proceedings of the National Academy of Sciences, the team from the UW’s reports that, though individual presses and pulses impacted penguins in a variety of ways, both were equally important for the future survival of the penguin population. They also found that these types of climate changes, taken together, are leading to an overall population decline at this particular site.

“We found that penguin survival doesn’t rest solely — or even largely — on one or a few climate effects,” said lead author T.J. Clark-Wolf, a 91̽��postdoctoral researcher in biology and center scientist. “Instead, many different presses and pulses impact penguin reproduction and survival over time.”

The study analyzed data collected at Punta Tombo from 1982 to 2019 by co-author , founder of the Center for Ecosystem Sentinels and a 91̽��professor of biology, and collaborators. The data include:

• survival and reproductive success for nearly 54,000 penguins at the site, which historically is where hundreds of thousands of Magellanic penguins have come to breed each summer
• climate conditions during each breeding season
• ocean conditions off the coast of Punta Tombo, where adults feed during the breeding season and bring food back to the nest to feed their chicks
• offshore ocean conditions along the coast of South America, where adults and juveniles feed when migrating outside of the breeding season

Clark-Wolf and senior author , a 91̽��assistant professor of biology, folded these data into an integrated population model that parsed out the effects of separate presses and pulses on penguin survival over time. They found that different climate effects had distinct impacts on the Punta Tombo population. For example, heat waves — a climate pulse — have a detrimental effect on the population by killing both adults and chicks, as illustrated by a 2019 single-day heat wave at Punta Tombo that killed more than 350 penguins. A climate press, increased rainfall at the site, also negatively impacted the population, because storms during the breeding season kill chicks due to exposure.

The gradual weakening of the plume of silt expelled into the ocean by the Río de la Plata, the second largest river basin in South America, is one press that positively affected penguin survival. This press impacts the penguins’ winter feeding waters off the coast of northern Argentina, Uruguay and Brazil. Past research by , a co-author on the new study and a 91̽��research scientist, has indicated that a weaker plume may make it easier for penguins, particularly females, to catch enough food each winter and return to the breeding site in prime condition.

But the positive effects of a weakening plume could not overcome the negative effects of other climate events at Punta Tombo, which over nearly four decades has become warmer and wetter. The number of breeding pairs at the site has declined from a high of approximately 400,000 in the early 1980s to about 150,000 in 2019.

“This colony will be 100 years old in 2024, but we finished another on-the-ground survey in late October at Punta Tombo and its numbers continue to decline,” said Boersma. “The penguins are instead moving north to be closer to their food.”

Surveys have reported that Magellanic penguins are establishing other breeding sites farther north on the South American coast in search of better foraging opportunities.

Understanding how these presses and pulses shape this population is crucial for informing conservation efforts, the researchers said.

“For conservation to be most effective, we need to know where, when and how to apply our limited resources,” said Abrahms. “Information generated by this study tells us which climate effects we need to worry about and which ones we don’t — and therefore can help us focus on measures that we know will have a positive impact.”

The decades of data faithfully collected at Punta Tombo made it possible for the team to consider the effects of long-term climate changes and extreme events in combination, and as a result, to better predict how climate will impact this population in the future. It is this same approach, they believe, that can help conservationists and scientists understand how climate shifts will shape other long-lived animal species across our warming globe.

Fieldwork over the years at Punta Tombo has been funded by the Wildlife Conservation Society; the ExxonMobil Foundation; the Pew Fellows Program in Marine Conservation; the Disney Worldwide Conservation Fund; the Chase, Cunningham, CGMK, Offield, Peach, Thorne, Tortuga and Kellogg Foundations; the Wadsworth Endowed Chair in Conservation Science at the UW; the Friends of the Penguins fund; and private to the Center for Ecosystem Sentinels.

For more information, contact Clark-Wolf at tc130053@uw.edu and Abrahms at abrahms@uw.edu.

As climate change alters environments across the globe, scientists have discovered that in response, many species are shifting the timing of major life events, such as reproduction. With an earlier spring thaw, for example, some flowers bloom sooner. But scientists don’t know whether making these significant changes in life history will ultimately help a species survive or lead to bigger problems.

A study published the week of June 27 in the shows for the first time that a species of large carnivore has made a major change to its life history in response to a changing climate — and may be worse off for it.

A team led by researchers at the 91̽��, in collaboration with Botswana Predator Conservation, a local NGO, analyzed field observations and demographic data from 1989 to 2020 for populations of the — Lycaon pictus. They discovered that, over a 30-year period, the animals shifted their average birthing dates later by 22 days, an adaptation that allowed them to match the birth of new litters with the coolest temperatures in early winter. But as a result of this significant shift, fewer pups survived their most vulnerable period because temperatures during their critical post-birth “denning period” increased over the same time period, threatening the population of this already endangered species.

This study shows that African wild dogs, which are distantly related to wolves and raise young cooperatively in packs, may be caught in a “phenological trap,” according to lead author , a 91̽��assistant professor of biology and researcher with the . In a phenological trap, a species changes the timing of a major life event in response to an environmental cue — but, that shift proves maladaptive due to unprecedented environmental conditions like climate change.

“It is an unfortunate ‘out of the frying pan, into the fire’ situation,” said Abrahms. “African wild dogs shifted birthing dates later in order to keep pace with optimal cool temperatures, but this led to hotter temperatures during the denning period once those pups were born, which ultimately lowered survival.”

The study demonstrates that species on high “trophic levels” in ecosystems — like large predators — can be just as sensitive to climate change as other species, something that scientists were uncertain about. Other research has shown that long-term warming can trigger phenological shifts, or shifts in the timing of major life events, in “primary producer” species like plants and “primary consumers” that feed on plants, including many birds and insects. But, until now, scientists had never documented a climate-driven phenological shift in a large mammalian carnivore. Abrahms and her colleagues show that large predators can indeed exhibit strong responses to long-term climate change, even though predators are “farther removed” up the food chain.

For this study, the team analyzed more than three decades of data that they and collaborators collected on 60 packs of African wild dogs that live across a more than 1,000 square-mile region of northern Botswana. This species breeds annually each winter. After birth, pups spend about 3 months with their mother at the den before beginning to travel and hunt with the pack.

Abrahms and her colleagues analyzed the dates that African wild dog mothers gave birth to their litters each year, which is how they determined that adults gradually delayed breeding by about one week per decade over the 30-year study period.

“Although most animal species are advancing their life history events earlier in the year with climate change, this finding represents a rare instance of a species delaying its life history, and at a rate twice as high as the average rate of change observed across animal species”, said Jeremy Cohen, a researcher at Yale University and the Center for Biodiversity and Global Change, who was not involved in the study.

Such a large shift is likely due to the rapid pace of warming in the region, and because African wild dogs have evolved to breed within a narrow “thermal window,” according to Abrahms.

The team used long-term demographic data to calculate how many pups survived the denning period each year. They discovered a correlation between temperatures during the denning period and survival: Warmer denning periods led to fewer pups recruiting to packs at the end of winter, which indicated that fewer pups survived the denning period.

Average daily maximum temperatures in the study period rose by about 1.6 degrees Celsius, or 2.9 degrees Fahrenheit, over 30 years. Over the same time frame, annual maximum temperatures spiked by 3.8 degrees Celsius — just over 6 degrees Fahrenheit.

The team could not have come to its unexpected conclusions without those decades of detailed field observations led by Botswana Predator Conservation, Abrahms said.

“We could only conduct this study because of the existence of this unique, long-term dataset for a large predator, which is really rare,” said Abrahms. “It shows the value for this kind of data in studying how climate change will impact ecosystems.”

The study area in northern Botswana is part of the largest continuous habitat for African wild dogs, which are threatened by habitat fragmentation and loss, disease and conflicts with people. The International Union for Conservation of Nature that there are only about 1,400 mature adults left in the wild.

“Large predators play extraordinarily important roles in ecosystems, but we still have a lot to learn about the implications of climate change for these animals,” said Abrahms. “Big climate-driven shifts like the one we found may be more widespread in top predators than originally thought, so we hope our findings will spur new climate-change research on other predator populations around the planet.”

Co-authors on the study are Kasim Rafiq, a 91̽��postdoctoral researcher in biology; Neil Jordan with the University of New South Wales; and J.W. McNutt with Botswana Predator Conservation. The research was funded by numerous public and private donors over the thirty-year study period.

For more information, contact Abrahms at abrahms@uw.edu.

A published Aug. 11 in the Proceedings of the Royal Society B by researchers at the 91̽�� and Stony Brook University reports on how bats and pepper plants in Central America have coevolved to help each other survive.

The team — led by , a 91̽��professor of biology and curator of mammals at the Burke Museum of Natural History and Culture — focused on the complex mixture of volatile organic compounds, or VOCs, produced by fruits on pepper plants in the genus Piper at prime ripeness. The study showed how these VOCs may have evolved to attract scent-oriented, short-tailed fruit bats from the genus Carollia, who then eat the fruits and excrete the seeds into the landscape.

Plant–animal interactions have captured the attention of biologists for centuries, and are key to maintaining the biodiversity of tropical ecosystems. The dispersal syndrome hypothesis — an explanation of how mutually beneficial relationships between plants and fruit-eating animals may lead to coevolution — proposes that, when animals are effective seed dispersers, they may select for fruit traits, including size, color and odor, that match their sensory abilities, such as vision and olfaction. But few studies have tested this hypothesis for complex traits like fruit scents. This research provides one of the first tests of bat-driven, fruit scent evolution.

The study is based on data collected during fieldwork at La Selva Biological Station in Costa Rica. There, Piper is highly diverse, with more than 50 recognized species. It is also a location where three Carollia species — C. castanea, C. sowellii and C. perspicillata — are some of the most abundant bats year-round and coexist with approximately 62 other bat species.

The team spent hundreds of hours searching and collecting ripe fruits from Piper to extract and quantify the VOCs that make up their fragrant scent. They also collected fecal samples from live bats and then released them back into the wild to determine which Piper species the bats were eating and how much. In addition, the researchers conducted behavioral experiments with wild bats where they offered options of unripe fruits enhanced with the most common VOCs found in local Piper plants. Video cameras and microphones recorded the bats’ feeding behaviors and echolocation calls.

The team found Piper fruit scent bouquets were complex and diverse. The authors identified and quantified 249 VOCs in ripe fruit scents across 22 Piper species. Some compounds were found in the fruit scent of most species — like alpha-caryophyllene, which has a spicy scent like cinnamon or cloves. Others, like 2-heptanol, were only found in a few Piper species. The diet experiments showed that, while the three Carollia fruit bat species varied in their reliance on Piper as a food source, all consumed a lot of a few Piper species, and a little of many others. Surprisingly, this was not related to how abundant the Piper species are at La Selva, so the bats must choose Piper fruits based on other characteristics and not just how well represented they are across the landscape. The team’s behavioral experiments provided some clues to what might be happening: Bats preferred samples spiked with 2-heptanol, a VOC found in the fruit scents of the Piper species they eat the most.

“These findings suggest bats use specific chemicals in the fruit scent bouquet not only to select ripe fruits, but to find the specific Piper species that make up the bulk of their diet,” said Santana, who is co-lead author on the study. “By helping them communicate with the bats, these chemical signals are likely a component of a dispersal syndrome in these plants.”

Through statistical and evolutionary analyses of the data on fruit scent chemistry and bat diet, the team further demonstrated that the evolutionary patterns of chemical diversity and the presence of specific compounds in Piper fruit scents is associated with greater bat consumption and scent preferences. This highlights the potential effect of bat fruit consumption on the evolution of fruit chemistry, a relationship that contributes to the extreme diversity of tropical fruiting plants worldwide.

“Flying in the dark means bats cannot find ripe fruit by sight, but rely on olfaction instead,” said co-author , a professor at Stony Brook University. “Olfaction is the bridge between the plant signal and bat fruit consumption, and finding the specific VOCs bats respond to opens the door to matching olfactory receptor genes to important VOCs, which has been impossible until now.”

Understanding the relationship between bats and pepper plants not only contributes to knowledge about coevolution of these species, but also has benefits for rainforest habitat conservation. Piper are some of the first plants to grow in forest gaps and edges, and Carollia ― as key dispersers of Piper seeds ― can help restore plant life in logged areas.

“Our current and future work is identifying the odorant receptors that allow the bats to detect the fruit scents. This will allow us to link the ecology and evolution of these relationships with the physiological mechanisms,” said co-author , a 91̽��professor of biology.

Co-lead author on the paper is former 91̽��postdoctoral researcher Zofia Kaliszewska. Other co-authors are 91̽��doctoral alum Leith Leiser-Miller, M. Elise Lauterbur at the University of Arizona and Jessica Arbour at Middle Tennessee State University. The research was funded by the National Science Foundation.

For high-resolution images, video and interviews, contact burkepr@uw.edu.

With , and in the coming decade a , 2021 could be a pivotal year in how governments, societies and families view the threat of climate change.

, an assistant professor of biology at the 91̽�� and its , is urging her fellow scientists to make their own pivot when it comes to climate change and another growing trend: conflicts between humans and wildlife. Human-wildlife conflicts can occur when people and wildlife move into the same area, or compete for the same resources, such as food.

As a handful of studies have shown, climate change is further exacerbating human-wildlife conflicts by straining ecosystems and altering behaviors, both of which can deepen the contacts — and potential competition — between people and animals. In an published July 30 in the journal Science, Abrahms calls for expanding research into the many ways that climate change will impact the complex interplay between human activities and wildlife populations.

In a recent conversation with 91̽��News, Abrahms explained how incorporating climate change into studies of human-wildlife interactions won’t just help scientists come up with ways to mitigate the effects of these conflicts. They could also alert policymakers, experts and ordinary citizens to potential sources of human-wildlife conflict before they even occur.

What led you to write this call to action?

I’ve been looking at this topic for some time. But I was really prompted when I had two clear examples from completely different ecosystems in front of me where extreme climate events led to a catastrophic conflict. That made me wonder how prevalent this is globally.

What were these examples?

In 2015 and 2016, there was a dramatic rise in the number of whales entangled in fishing gear off the west coast of the United States. There was a really unprecedented marine heat wave off of the coast of North America that had two effects. First, whales moved farther inshore to chase where their prey had moved during the heat wave. Second, it changed the timing of the Dungeness crab fishing season. This conjunction of the change in how whales use their available space in the ocean and the timing of this fishery created this perfect storm of overlap and .

The second example came from a report by the government of Botswana, which is where I’ve done a lot of my fieldwork. It cited the some of the highest numbers of human-wildlife conflicts on record — primarily large carnivores preying on livestock — during an extreme drought in 2018.

Why is it important to consider how climate change is driving human-wildlife conflicts?

Human-wildlife conflicts have been widely studied. Research shows that they have huge implications for biodiversity, human health, economics, quality of life and much, much more. But a more concerted effort by scientists to consider the influence of climate change on these conflicts could help us anticipate when these conflicts occur — maybe even avoid them.

How many studies of human-wildlife conflict make a connection to climate change?

We’ve been looking in the scientific literature and government reports. At most we see a few dozen. But these are disparate incidents, studied and reported in isolation, and it’s hard to compare them to one another. Some are anecdotal, like the report in Botswana. Others make more direct connections between environmental conditions and human-wildlife contact, like the whale entanglements. I’m hopeful because we’re seeing more and more governing bodies recognizing this connection, including . But there hasn’t been this direct recognition by the broader scientific community that climate change is going to fuel more intense and more frequent human-wildlife conflicts.

Why do you think more studies haven’t considered the role of climate?

I think it’s such a complex process. There is so much that goes into creating those conflicts. Understanding them involves understanding the ecosystem, as well as the social or economic drivers that lead people to use space or resources that put them into competition with animals. Human relationships or attitudes to wildlife play a huge role as well, in terms of how much tolerance people have for coming into contact with wildlife, and how they respond to those encounters and potential property damage or economic loss from wildlife.

These are critical considerations. But I think there’s been so much focus on ecological and social considerations that there’s been less consideration of the physical environment. That’s not to say people haven’t been looking into the physical environment. We’ve seen dozens of studies, as I’ve said. But most are localized studies or government reports.

What are some ways that climate factors influence human-wildlife conflicts?

A lot of the cases we’ve seen are a clear rise in conflict either during or just after an extreme climate event, like the marine heatwave that fueled a rise in whale entanglements off the West Coast or the rise in human-wildlife conflicts during and after the severe drought in Botswana.

But we also see a rise in conflicts due to climate variability. A two-decade in New Mexico reported that the frequency of black bears coming into contact with humans and livestock fluctuates with the El Niño/La Niña cycle. Basically, La Niña creates drought conditions for bears, and they’ll wander more widely for food and exploit alternative food resources – and then you see greater reports of bears coming into contact with livestock, damaging property and digging through garbage.

Long-term climate shifts also create conflict. In India, long-term climate change the amount of preferred vegetation for blue sheep, or bharal, which have moved into lower elevations to feed on human crops. That’s a conflict in itself, but the movement of bharal has also drawn down snow leopards, which creates additional problems.

What are some of the lesser-known consequences of human-wildlife conflicts?

Lots of studies have looked at human-wildlife conflicts — outside of climate change — and their long-term consequences. In parts of Western and Central Africa, have linked the rise of baboon populations, whose predators have been exterminated by people, with a rise in child labor. Baboons can be very aggressive and can raid crops, and in response children were pulled out of school to guard agricultural fields.

These conflicts can also fuel the rise of diseases. In the U.S., removing pumas led to an explosion of deer populations, which in turn fueled a rise in Lyme disease. You can also see new diseases emerge, because when humans and wildlife come into closer contact there are opportunities for diseases to jump from animals to people.

Can studying human-wildlife conflicts help mitigate them?

Oh my gosh, yes! There are so many good examples, and there’s a rich literature around conflict mitigation techniques. One creative method piloted by some of my colleagues in Botswana involves on the back end of cattle, because predators are less likely to attack something that’s looking at them directly.

Elephants can sometimes move into agricultural areas to forage on crops. Researchers have found that putting up bee hive “fences” can actually deter this.

What about efforts to mitigate human-wildlife conflicts caused by climate change?

The clearest example that comes to mind of something actually being implemented is for the whale entanglements off of the West Coast. In that situation, there was a clear link between oceanographic conditions, animal behavior and human behavior. The California Department of Fish and Wildlife, which regulates the Dungeness crab fishery, began to take real-time oceanographic conditions into account when deciding the start and end dates for the Dungeness crab fishing season. This is a concerted effort to try to proactively reduce the chances of whale entanglements in nets, and to me it is a gold standard for a policy that takes climate variability into account.

But with research, there is potential to develop more mitigation efforts. If you know a certain conflict will rise in an El Niño year, for example, you could have a conflict-reduction policy in place and ready to implement when forecasts show an El Niño forming.

There are also some exciting underway to predict when conflicts are likely to occur. These can help forewarn wildlife managers and ordinary citizens, so that they can be proactive in taking steps to avert conflict. But these efforts don’t currently take into account what the climate is doing. This seems like a perfect opportunity to fold in our growing understanding of how climate conditions may factor into conflict.

There are a lot of efforts under development or in place to mitigate human-wildlife conflicts, but they don’t currently take climate into account. If good research can reveal the role of climate, it could be possible to modify those methods to make them responsive to environmental conditions. And really, reducing conflict is our goal here. The more that we know about when conflicts are more likely to occur, the more we can prepare for those conflicts or intervene to avoid them altogether.

For more information, contact Abrahms at abrahms@uw.edu.

A new published April 30 in the identified three factors critical in the rise of mammal communities since they first emerged during the Age of Dinosaurs: the rise of flowering plants, also known as angiosperms; the evolution of tribosphenic molars in mammals; and the extinction of non-avian dinosaurs, which reduced competition between mammals and other vertebrates in terrestrial ecosystems.

Previously, mammals in the Age of Dinosaurs were thought to be a relatively small part of their ecosystems and considered to be small-bodied, nocturnal, ground-dwelling insectivores. According to this long-standing theory, it wasn’t until the about 66 million years ago, which wiped out all non-avian dinosaurs, that mammals were then able to flourish and diversify. An astounding number of fossil discoveries over the past 30 years has challenged this theory, but most studies looked only at individual species and none has quantified community-scale patterns of the rise of mammals in the Mesozoic Era.

Co-authors are Meng Chen, a 91̽�� alumnus and current postdoctoral researcher at Nanjing University; , a 91̽�� biology professor and curator of paleobotany at the UW’s ; and , a 91̽��associate professor of biology and Burke Museum curator of vertebrate paleontology. The team created a Rubik’s Cube-like structure identifying 240 “eco-cells” representing possible ecological roles of mammals in a given ecospace. These 240 eco-cells cover a broad range of body size, dietary preferences, and ways of moving of small-bodied mammals. When a given mammal filled a certain type of role or eco-cell, it filled a spot in the ‘Rubik’s Cube.’ This method provides the first comprehensive analysis of evolutionary and ecological changes of fossil mammal communities before and after K-Pg mass extinction.

“We cannot directly observe the ecology of extinct species, but body size, dietary preferences and locomotion are three aspects of their ecology that can be relatively easily inferred from well-preserved fossils,” said Chen. “By constructing the ecospace using these three ecological aspects, we can visually identify the spots filled by species and calculate the distance among them. This allows us to compare the ecological structure of extinct and extant communities even though they don’t share any of the same species.”

The team analyzed living mammals to infer how fossil mammals filled roles in their ecosystems. They examined 98 small-bodied mammal communities from diverse biomes around the world, an approach that has not been attempted at this scale. They then used this modern-day reference dataset to analyze five exceptionally preserved mammal paleocommunities ― two Jurassic Period and two Cretaceous Period communities from northeastern China, and one Eocene Epoch community from Germany. Usually Mesozoic Era mammal fossils are incomplete and consist of fragmentary bones or teeth. Using these remarkably preserved fossils enabled the team to infer ecology of these extinct mammal species, and look at changes in mammal community structure during the last 165 million years.

The team found that, in current communities of present-day mammals, ecological richness is primarily driven by vegetation type, with 41 percent of small mammals filling eco-cells compared to 16 percent in the paleocommunities. The five mammal paleocommunities were also ecologically distinct from modern communities and pointed to important changes through evolutionary time. Locomotor diversification occurred first during the Mesozoic, possibly due to the diversity of microhabitats, such as trees, soils, lakes and other substrates to occupy in local environments. It wasn’t until the Eocene that mammals grew larger and expanded their diets from mostly carnivory, insectivory and omnivory to include more species with diets dominated by plants, including fruit. The team determined that the rise of flowering plants, new types of teeth and the extinction of dinosaurs likely drove these changes.

Before the rise of flowering plants, mammals likely relied on conifers and other seed plants for habitat, and their leaves and possibly seeds for food. By the Eocene, flowering plants were both diverse and dominant across forest ecosystems. Flowering plants provide more readily available nutrients through their fast-growing leaves, fleshy fruits, seeds and tubers. When becoming dominant in forests, they fundamentally changed terrestrial ecosystems by allowing for new modes of life for a diversity of mammals and other forest-dwelling animals, such as birds.

“Flowering plants really revolutionized terrestrial ecosystems,” said Strömberg. “They have a broader range of growth forms than all other plant groups ― from giant trees to tiny annual herbs ― and can produce nutrient-rich tissues at a faster rate than other plants. So when they started dominating ecosystems, they allowed for a wider variety of life modes and also for much higher ‘packing’ of species with similar ecological roles, especially in tropical forests.”

Tribosphenic molars ― complex multi-functional cheek teeth ― became prevalent in mammals in the late Cretaceous Period. Mutations and natural selection drastically changed the shapes of these molars, allowing them to do new things like grinding. In turn, this allowed small mammals with these types of teeth to eat new kinds of foods and diversify their diets.

Lastly, the K-Pg mass extinction event that wiped out all dinosaurs except birds 66 million years ago provided an evolutionary and ecological opportunity for mammals. Small body size is a way to avoid being eaten by dinosaurs and other large vertebrates. The mass extinction event not only removed the main predators of mammals, but also removed small dinosaurs that competed with mammals for resources. This ecological release allowed mammals to grow into larger sizes and fill the roles the dinosaurs once had.

“The old theory that early mammals were held in check by dinosaurs has some truth to it,” said Wilson. “But our study also shows that the rise of modern mammal communities was multifaceted and depended on dental evolution and the rise of flowering plants.”

###

For more information contact Andrea Godinez with the 91̽��Burke Museum at burkepr@uw.edu.

Burke Museum story .

Across North America, coyotes are moving into urban environments, and regardless of how they feel about it, urban residents are having to get used to some new animal neighbors. A big question for wildlife researchers is how coyotes habituate to humans, which can potentially lead to conflict.

A study led by a 91̽�� Tacoma faculty member, recently in Ecology and Evolution, suggests coyotes can habituate to humans quickly and that habituated parents pass this fearlessness on to their offspring.

“Even if it’s only 0.001 percent of the time, when a coyote threatens or attacks a person or a pet, it’s national news, and wildlife management gets called in,” said first author , an assistant professor at 91̽��Tacoma. “We want to understand the mechanisms that contribute to habituation and fearlessness, to prevent these situations from occurring.”

The study, done as part of Schell’s doctoral work at the University of Chicago, focused on eight coyote families at the U.S. Department of Agriculture’s in Millville, Utah. The research center was founded in the 1970s to reduce coyote attacks on sheep and other livestock.

Until the 20th century, Schell said, coyotes lived mostly in the Great Plains. But when wolves were hunted almost to extinction in the early 1900s, coyotes lost their major predator, and their range began to expand. With continuing landscape changes, coyotes are now increasingly making their way into suburban and urban environments — including , Los Angeles and cities in the Pacific Northwest — where they live, mainly off rodents and small mammals, without fear of hunters.

The new study seeks to understand how a skittish, rural coyote can sometimes transform into a bold, urban one — a shift that can exacerbate negative interactions among humans and coyotes.

“Instead of asking, ‘Does this pattern exist?’ we’re now asking, ‘How does this pattern emerge?'” Schell said.

A key factor may be parental influence. Coyotes pair for life, and both parents contribute equally to raising the offspring. This may be because of the major parental investment required to raise coyote pups, and the evolutionary pressure to guard them from larger carnivores.

The new study observed coyote families at the Utah facility during their first and second breeding seasons. These coyotes are raised in a fairly wild setting, with minimal human contact and food scattered across large enclosures.

But during the experiment researchers occasionally placed all the food near the entrance of the enclosure and had a human researcher sit just outside, watching any approaching coyotes, from five weeks to 15 weeks after the birth of the litter. Then they documented how soon the coyotes would venture toward the food.

“For the first season, there were certain individuals that were bolder than others, but on the whole they were pretty wary, and their puppies followed,” Schell said. “But when we came back and did the same experiment with the second litter, the adults would immediately eat the food — they wouldn’t even wait for us to leave the pen in some instances.

“Parents became way more fearless, and in the second litter, so, too, were the puppies.”

In fact, the most cautious pup from the second-year litter ventured out more than the boldest pup from the first-year litter.

The study also looked at two hormones in the coyotes’ fur — cortisol, the “fight or flight” hormone, and testosterone. The second litter of pups had mothers who experienced more stress during pregnancy, due to the researchers’ presence during the experiment, so that may have affected their development in the womb. But hormonal changes do not seem to have been passed down in that way.

Instead, the fur samples showed that the bolder pups had higher cortisol levels in their blood, meaning they ventured to the food despite their fear of humans. Further work would confirm whether, as Schell suspects, the cortisol levels would decline over time as the coyotes began to discount the human threat.

“The discovery that this habituation happens in only two to three years has been corroborated, anecdotally, by evidence from wild sites across the nation,” Schell said. “We found that parental effect plays a major role.”

Since arriving at 91̽��Tacoma, Schell has begun working with Point Defiance Zoo & Aquarium to launch the , which will use infrared motion-capture cameras to track coyotes and raccoons throughout the region. It’s part of the Chicago-based , studying urban wildlife across the country.

Other co-authors of the recent paper include at the U.S. Department of Agriculture’s Predator Research Facility in Utah; at Franklin and Marshall College in Pennsylvania; , who has a joint appointment at the University of Chicago and Chicago’s Lincoln Park Zoo, and , the latter two serving as Schell’s doctoral co-advisors at the University of Chicago. The study was supported by the University of Chicago, the National Science Foundation and the U.S. Department of Agriculture.

###

For more information, contact Schell at cjschell@uw.edu or 253-692-5838.

Under climate change, plants and animals will shift their habitats to track the conditions they are adapted for. As they do, the lands surrounding rivers and streams offer natural migration routes that will take on a new importance as temperatures rise.

An open-access led by the 91̽�� pinpoints which riverside routes in Washington, Oregon, Idaho and western Montana will be the most important for animals trying to navigate a changing climate. The study was published this fall in PLOS One.

“This corridor network is already there, and it’s already important for animal movement,” said lead author , a scientist in the UW’s Climate Impacts Group. “Under climate change these will become ‘superhighways’ for animals that are seeking new places to live. We’ve identified ones that could be priorities for conservation and restoration.”

Riparian areas — areas of habitat along the banks of rivers and streams — are known to be used by bears, coyotes, wolves, deer, mountain lions and other large mammals. But these regions could also benefit smaller mammals, like beavers and marmots, and even insects, birds and other species looking for cooler, moister terrain as conditions become less habitable.

“We aren’t the first to realize that riparian areas are likely to be really important for animals seeking refuge from warmer or drier conditions, or for connecting fragmented habitats under climate change,” Krosby said. “But we hadn’t seen anybody identify which riparian areas would be particularly valuable in the future.”

The authors developed a ranking system for riparian areas and applied it to the Northwest, creating a general technique that could be applied elsewhere. They rated the land surrounding rivers and streams for various features that would help animals on the move: width; amount of shade; tree cover; connection across temperature gradients; and general condition of the landscape.

Results show that the highest-quality routes in the Northwest are mostly in the mountains, which have shaded, well-protected riparian corridors that connect warmer to cooler habitats.

The authors then looked at which areas should be priorities for restoration — places that are not currently protected, or that offer the only natural pathway linking warmer and cooler landscapes. Here the routes through the Columbia Plateau, covering Eastern Washington, central Oregon and western Idaho, popped out as particularly important.

“If you look at an aerial photograph of an agricultural or urban landscape you’ll see these green corridors that follow streams and rivers,” Krosby said. “Humans use the flat areas of the landscape: we live there, we farm there, we use it for all kinds of things. So the riparian areas in these landscapes may not be in the best shape, but in some ways they’re the most valuable, because they’re the only natural habitat left.”

The authors don’t identify individual waterways as priorities for riparian conservation. Instead they leave it to regional managers to single out individual areas and choose methods — whether it be working with landowners to keep areas in a natural state, planting native vegetation, removing invasive species along streams, creating easements in property deeds, or other methods — to ensure that riverside land remains friendly to wildlife movement.

“Riparian areas offer a huge bang-for-buck as conservation opportunities in the effort to reconnect our fragmented habitats,” Krosby said. “The nice thing about riparian conservation is it’s a two-fer: The same vegetation that provides cover for terrestrial species moving through riparian zones can, for example, help shade streams to cool water temperatures for aquatic species.”

The study is part of a growing trend in wildlife conservation. This winter, the state of Washington anticipates opening a over Interstate 90 at Snoqualmie Pass, which will allow animals to safely cross the freeway. That infrastructure in combination with other measures could help animal populations be more resilient to climate change.

“The idea is to have a whole network: You want to make sure that your landscape is permeable to wildlife movement,” Krosby said. “That’s important now, and it’s especially important under climate change, because moving to track shifting habitats is the primary way that species deal with a changing climate.”

The research was funded by the Washington Department of Fish & Wildlife, the North Pacific Landscape Conservation Cooperative, the U.S. Fish and Wildlife Service and the Wilburforce Foundation.

Co-authors are David Theobald at Conservation Science Partners, Robert Norheim at the UW’s Climate Impacts Group, and the late Brad McRae at The Nature Conservancy.

###

For more information, contact Krosby at 206-579-8023 or mkrosby@uw.edu.

WDFW grant: 10-1515; USFWS grant: Fl2AC01044; Wilburforce grant: UNIVE1211

A recent published in the open-access journal PLOS ONE finds that common ragweed will expand its range northward as the climate warms, reaching places including New York, Vermont, New Hampshire, and Maine, while retreating from some current hot spots.

“It was surprising that nobody had looked at ragweed distributions in the U.S.: As climate conditions are changing, where will it spread to in the future?” said corresponding author , who did the work as a postdoctoral researcher in the 91̽��School of Environmental and Forest Sciences.

Ragweed is a native North American plant that thrives in open areas, moving quickly into disturbed areas. It produces copious fine-powder pollen from August to November, causing sneezing, runny noses, irritated eyes, itchy throats and headaches for people with hay fever.

Several studies of ragweed’s future geographic distribution have been done in Europe, where people are concerned because this invasive species is expanding its range. This is the first study to consider future ragweed distribution in the United States.

Case’s previous research looks at how climate change may influence the distribution of various species, mainly native trees in the Pacific Northwest. Co-lead author , an assistant professor of plant ecology at UMass Amherst, is an expert on ragweed, including mapping allergy hot spots in New England.

“One reason we chose to study ragweed is because of its human health implications. Ragweed pollen is the primary allergen culprit for hay fever symptoms in summer and fall in North America, so it affects a lot of people,” Stinson said.

For the new study, the two authors built a machine learning model using Maxent software that takes some 726 observations of common ragweed in the eastern U.S., drawn from an international biodiversity database, then combines those with climate information to identify conditions that allow the plant to thrive. Researchers next ran the model into the future using temperature and precipitation output from 13 global climate models under two different pathways for future greenhouse gas emissions.

The results show that roughly 35 years from now, ragweed is projected to expand northward into places where it has not been documented, including upstate New York, including the Albany area, New Hampshire, Maine and Vermont.

While that news may be ominous, knowing the plant is coming may help those communities prepare.

“Weed control boards, for example, might include ragweed on their list to keep an eye out and monitor for,” Case said. “Historically they might not have been looking for ragweed, but our study suggests maybe they should start looking for it.”

The study only covers the region east of the Mississippi River because that’s where there were enough ragweed observations to run the model. The plant is commonly found in Illinois, Florida and the eastern seaboard from Washington, D.C. to Rhode Island. It is possible that ragweed would also expand its range westward or north into Canada, Case said, but those areas were outside the scope of the study.

The study also finds regions where ragweed is prevalent today but will decline substantially in the future, including the southern Appalachian Mountains, central Florida and northeastern Virginia. And knowing that, too, might be useful.

“As the climate becomes less suitable, there may be opportunities to try and displace ragweed. Maybe that is the silver lining — that there are some opportunities for those communities to actually get some headway on mitigating or even eradicating this species,” Case said.

Models show an overall surge in ragweed in the eastern U.S. by the 2050s, followed by a slight overall contraction from the 2050s to the 2070s, as temperature and precipitation become more variable.

“It is kind of an interesting case study of climate change effects: It’s not all bad, it’s not all good,” Case said.

“We don’t have a lot of models like this that tell us where individual species may go under different scenarios,” Stinson said. “Ecologists are working on doing this type of study for more species, but there are not always enough data points from around the world; individual species data are rare. But ragweed happens to be quite abundant, which made this study feasible.”

The research was funded by the U.S. Environmental Protection Agency and the University of Massachusetts. Case now has a position in Seattle with The Nature Conservancy.

###

For more information, contact Case at mcase@uw.edu or 206-913-1326 and Stinson at kstinson@eco.umass.edu or 413-577-3044.