To avoid humans, more wildlife now work the night shift

To avoid humans, more wildlife now work the night shift

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Red fox under cover of darkness in London. Jamie Hall. For use only with this article.


By Kaitlyn Gaynor, PhD Candidate

For their first 100 million years on planet Earth, our mammal ancestors relied on the cover of darkness to escape their dinosaur predators and competitors. Only after the meteor-induced mass extinction of dinosaurs 66 million years ago could these nocturnal mammals explore the many wondrous opportunities available in the light of day.

Fast forward to the present, and the honeymoon in the sun may be over for mammals. They’re increasingly returning to the protection of night to avoid the Earth’s current terrifying super-predator: Homo sapiens.

My colleagues and I have made the first effort to measure the global effects of human disturbance on the daily activity patterns of wildlife. In our new study in the journal Science, we documented a powerful and widespread process by which mammals alter their behavior alongside people: Human disturbance is creating a more nocturnal natural world.

Many catastrophic effects of humans on wildlife communities have been well-documented: We are responsible for habitat destruction and overexploitation that have imperiled animal populations around the world. However, just our presence alone can have important behavioral impacts on wildlife, even if these effects aren’t immediately apparent or easy to quantify. Many animals fear humans: We can be large, noisy, novel and dangerous. Animals often go out of their way to avoid encountering us. But it’s becoming more and more challenging for wildlife to seek out human-free spaces, as the human population grows and our footprint expands across the planet.

A badger explores a South London cemetery at night. Laurent Geslin. For use only with this article.

Global increase in nocturnality

My collaborators and I noticed a striking pattern in some of our own data from research in Tanzania, Nepal and Canada: animals from impala to tigers to grizzly bears seemed to be more active at night when they were around people. Once the idea was on our radar, we began to see it throughout the published scientific literature.

It appeared to be a common global phenomenon; we set out to see just how widespread this effect was. Might animals all over the world be adjusting their daily activity patterns to avoid humans in time, given that it is becoming harder to avoid us in space?

To explore this question, we conducted a meta-analysis, or a study of studies. We systematically scoured the published literature for peer-reviewed journal articles, reports and theses that documented the 24-hour activity patterns of large mammals. We focused on mammals because their need for plenty of space often brings them into contact with humans, and they possess traits that allow for some flexibility in their activity.

We needed to find examples that provided data for areas or seasons of low human disturbance – that is, more natural conditions – and high human disturbance. For example, studies compared deer activity in and out of the hunting season, grizzly bear activity in areas with and without hiking, and elephant activity inside protected areas and outside among rural settlement.

Based on reported data from remote camera traps, radio collars or observations, we determined each species’ nocturnality, which we defined as the percentage of the animal’s total activity that occurred between sunset and sunrise. We then quantified the difference in nocturnality between low and high disturbance to understand how animals changed their activity patterns in response to people.

For each species, researchers compared the animals’ active periods when people are nearby to when people aren’t around. The distance between the grey and red dot pair for each animal shows how extreme the shift in nocturnality. Reprinted with permission from Gaynor et al., Science 360:1232 (2018). For use only with this article.

Overall, for the 62 species in our study, mammals were 1.36 times as nocturnal in response to human disturbance. An animal that naturally split its activity evenly between the day and night, for example, would increase its nighttime activity to 68 percent around people.

While we expected to find a trend toward increased wildlife nocturnality around people, we were surprised by the consistency of the results around the world. Eighty-three percent of the case studies we examined showed some increase in nocturnal activity in response to disturbance. Our finding was consistent across species, continents and habitat types. Antelope on the savanna of Zimbabwe, tapir in the Ecuadorian rainforests, bobcats in the American southwest deserts – all seemed to be doing what they could to shift their activity to the cover of darkness.

Perhaps most surprisingly, the pattern also held across different types of human disturbance, including activities such as hunting, hiking, mountain biking, and infrastructure such as roads, residential settlement and agriculture. Animals responded strongly to all activities, regardless of whether people actually posed a direct threat. It seems human presence alone is enough to disrupt their natural patterns of behavior. People may think our outdoor recreation leaves no trace, but our mere presence can have lasting consequences.

Future of human-wildlife coexistence

We don’t yet understand the consequences of this dramatic behavioral shift for individual animals or populations. Over millions of years, many of the animals included in our study have evolved adaptations to living in the daylight.

Sun bears retreat from the sunny hours when people are nearby. Hakumakuma/Shutterstock

Sun bears, for example, are typically diurnal and sun-loving creatures; in undisturbed areas less than 20 percent of their activity occurred at the night. But they increased their nocturnality to 90 percent in areas of the Sumatran forest where intensive forest research activity created a disturbance.

Such diurnally adapted animals may not be as successful at finding food, avoiding predators or communicating in the darkness, which could even reduce their survival or reproduction.

However, because our mammalian ancestors evolved under the cover of darkness in the time of the dinosaurs, most mammal species possess traits that allow for some flexibility in their activity patterns. As long as animals are able to meet their needs during the night, they may actually thrive in human-dominated landscapes by avoiding daytime direct encounters with people that could potentially be dangerous for both parties. In Nepal, for example, tigers and people share the exact same trails in the forest at different times of day, reducing direct conflict between humans and these large carnivores. Dividing up the day, through what researchers call temporal partitioning, may be a mechanism by which people and wildlife can coexist on an ever more crowded planet.

An increase in nocturnality among certain species may also have far-reaching consequences for ecosystems, reshaping species interactions and cascading through food webs. In California’s Santa Cruz Mountains, coyotes are becoming more nocturnal in areas with human recreation. By analyzing coyote scat, scientists have linked this behavioral change to dietary shifts from diurnal to nocturnal prey, with implications for small mammal communities and for competition with other predators.

European beaver active at night in Orléans, France. Laurent Geslin. For use only with this article.


Working on this study reminded me that people aren’t alone on the planet. Even if we don’t see large mammals while we’re out and about during the day, they may still be living alongside us, asleep while we are awake and vice versa. In areas where threatened species live, managers may consider restricting human activity to certain times of the day, leaving some daylight just for wildlife.

The ConversationAnd it is likely that we need to preserve wilderness areas entirely free of human disturbance to conserve the most vulnerable and sensitive mammal species. Not all animals are willing or able to just switch to a nocturnal lifestyle around people. Those that try to avoid human disturbance entirely may be most vulnerable to the consequences of the expanding human footprint.


Kaitlyn Gaynor, Ph.D. Candidate in Environmental Science, Policy and Management, University of California, Berkeley

This article was originally published on The Conversation. Read the original article.

Check out more coverage on this study covered in The AtlanticOutside MagazineScientific AmericanLA TimesThe Guardian

Perspective from the Field: Will Forests Have a Vote in Colombia’s 2018 Elections?

Perspective from the Field: Will Forests Have a Vote in Colombia’s 2018 Elections?

By Lauren Withey, PhD Candidate

At the end of May, Colombia will hold the first round of Presidential Elections to decide the heir to the challenges of implementing the peace accord current President Juan Manuel Santos reached with the FARC guerillas in 2016. The accord was finalized in the end of 2016, but the hiccups and dramas of the four-year negotiations and ratification have continued through the implementation phase. The current government is trying to realize their commitments in a time of financial strain – with oil prices down, government coffers are depleted, leading to budget cuts that would seem to possibly undermine some of the priorities of the peace deal, particularly in the realm of the environment. The country’s 2018 budget for the environment and sustainable development is down 8.8 percent from the year before.

This dip in funding is unfortunate, especially as there has been much talk of the possibilities of “green” development for Colombia in the post-accord phase: a less extractive-intensive economy aligns well with the spirit of the accord, and there is an expansive opportunity for Colombia to cash-in on its stunning and varied landscapes via ecotourism, an industry long stifled by the conflict. The country has been quick to sign onto international commitments and ambitious goals to reduce deforestation, but reaching these targets hasn’t gotten any easier, as the end of the conflict has seen an uptick in deforestation rates – up 44 percent in 2016 over the previous year. This surprised few, given the role the FARC played in strategically maintaining forest cover in the many forested parts of the country it controlled.

the end of the conflict has seen an uptick in deforestation rates – up 44 percent in 2016 over the previous year

These challenges have provoked great interest on the part of international organizations to fill this funding gap by supporting Colombia in its efforts to maintain forest cover, primarily toward climate change mitigation ends. Colombia’s government has received funding from various bilateral donors (Germany, Norway, and the UK, among others) and multilateral donors (including via multiple programs of the World Bank and the United Nations) to fight deforestation. Much of this ~308 million USD has come in specifically to support the UNFCCC1 program known as REDD+ (Reduced Emissions from Deforestation and Degradation “Plus”), which is meant to reduce deforestation and thereby its threats to climate change by paying states and communities for their reductions in deforestation rates.

Prime Minister Erna Solberg of Norway and President Juan Manuel Santos of Colombia shake hands in front of local indigenous leaders during their April trip to Leticia in the Colombian Amazon, where they announced a new pact to reduce deforestation across Colombia. Whether Norway would continue such support under a new president, especially one that roles back parts of the peace deal, remains unclear. Photo by Juan David Tena – SIG

Most of the money that Colombia has received to date has not gone to ground-level efforts to reduce deforestation, but rather to making plans for reducing deforestation and to building the capacity of the appropriate government agencies to measure forest cover and carbon.2 However, there has been one notable large-scale effort to shift deforestation dynamics on the ground via a REDD+ project sponsored by the US Agency for International Development (USAID). As additional funding begins to flow in from these bilateral donors to support more of these efforts – such as the commitment of 50 million USD per year that the Norwegian Prime Minister made to President Santos in a press conference in the Colombian Amazon in early April – it is important to make sure that they have learned from these initial efforts led by USAID.

The two years I spent (2016-2017) researching this USAID program, which took place in the tropical rainforests of Colombia’s Pacific Coast, indicate that these deforestation reduction efforts are likely to fall victim to the same suite of vexing issues that plague the peace process in other realms. These include, first and foremost, the ongoing control of much of the country by armed actors – including dissident members of the FARC; other guerillas; and paramilitaries and their offshoots, many of whom are tied to politicians. These thrive on deforesting activities of coca cultivation, gold mining, timber harvesting, monoculture agriculture, and land speculation, and do the dirty work of continuing Colombia’s long history of dispossession of rural farmers from their lands in the process. Second, this deforestation is tied to a lack of access to legal means of subsistence for rural dwellers and those pushed off their land as part of the wider conflict.

While those promoting REDD+ in Colombia seek to resolve this latter issue of livelihood access by paying rural communities to defend the forests around them and offering them “alternative development” projects in the short term, the former set of issues complicate this theory of change. Indeed, hundreds of community activists have been killed by these armed actors since the accords took effect, continuing a long trend of threats and death to those who defend their territories against armed groups in Colombia. As I have seen in my research, the best hope for REDD+’s success is among communities that have legal control of their lands and strong leadership committed to maintaining this control and developing access to legal livelihoods for their community members. The fact that so many of these leaders across Colombia have been killed or forced to flee is obviously a threat to the success of any effort to establish peace, offer more secure livelihoods to rural people, and reduce pressure on the forest. Any positive move to reduce deforestation in Colombia then requires strengthening the implementation of the accord, and going beyond that to address the other actors that are undermining these three supposed concerns of the government.

the best hope for REDD+’s success is among communities that have legal control of their lands and strong leadership committed to maintaining this control and developing access to legal livelihoods for their community members

But while President Santos, who prioritized the peace process above all else, may recognize these mutualistic underlying drivers of discord and deforestation, this is not guaranteed to be the case with his successor. Indeed, the presidential candidate currently leading Colombian polls, Ivan Duque, has suggested he would try to roll back at least part of the peace accord – which could doom the process given the painstaking negotiations and tradeoffs that went into each element of the accord. He has mentioned little about forests other than his ambition to “protect biodiversity” and promote tree plantations – and got his facts wrong about the greatest driver of deforestation in the country in a recent debate on the subject. What his policies might look like in practice are, of course, harder to decipher at this stage. Yet, as Colombians head to the polls on May 27th, my work in Colombia’s Pacific suggests that in the balance lies not only the future of peace in Colombia – both with the FARC and with these other armed actors – but also the future of its rural regions and their forests. If international funders like Norway decide to continue to push their agenda to reduce deforestation in the country in the wake of the elections, they would be wise to emphasize the priorities of the accord, and support the new president in coming to grips with the joint underlying drivers of violence, displacement, inequality, and deforestation across rural Colombia.

1 UN Framework Convention on Climate Change
2 This is by design within the UNFCCC, which has encouraged a phased approach to REDD+ implementation. The first phase is a readiness phase in which countries are supposed to build up their capacity handle REDD+ funds through these different planning and capacity-building processes.

Telling stories at the International Congress for Conservation Biology

By Alex McInturff and Lauren Withey, PhD Candidates

To many Colombians, their country is poised for an incredible transformation. Colombia’s reputation internationally has long been marked by civil war and cocaine production. However, a 2016 peace accord between the government and the nation’s largest guerrilla army (FARC) offers hope not just for the resolution of real internal conflict, but for a shift in global attention as well. With improved security, many Colombians envision a country that can be famous not for its conflicts, but for its vast biodiversity, potential for ecotourism, and opportunity for new scientific exploration.

It was amid this transformative moment that the International Congress for Conservation Biology (ICCB) docked in Colombia’s Caribbean port city of Cartagena for the last week of July. The Congress, attended by academics and practitioners from around the world, covered an impressive range of topics, from new uses for agent-based modeling to strategies for diversifying the conservation community. Many sessions focused specifically on the host country’s particular conservation challenges and opportunities.

Brashares Group members were active participants in the conference, with several lab members giving talks and posters. The group also hosted a boundary-pushing symposium titled “Conservation and Storytelling in a Post-Truth World,” which sought to answer to important but overlooked questions:

  1. How can we use storytelling for more effective conservation?
  2. What can listening to the stories of others offer to conservation?

The Brashares Group settled on this topic in the context of a year of global political upheavals that many have claimed relied on stories rather than reality to achieve their successes. The Oxford English Dictionary went as far as declaring “post-truth” the word of the year in 2016. Our symposium explored what it meant to study and practice conservation in a world in which stories have so much power. Not willing to give into the doom and gloom, though, our six presenters also sought redeeming uses of stories that would help improve our understanding of our conservation goals and our means for achieving them.

Above: Kira Cassidy and Alex McInturff.

Kira Cassidy, of the Yellowstone Wolf project, and Alex McInturff, of the Brashares Group, argued that conservation, as a crisis discipline, and ecology, filled with exciting characters and high drama, are sciences particularly suited to absorbing stories. “Storytelling is our superpower,” Cassidy argued, while McInturff argued that stories have the dual abilities to make our messages simple and digestible, while also giving us access to a world of symbols and narrative truths that characterize much of our lives and politics.

Above: Stefano Wrobleski

Stefano Wrobleski, of, showed us the human side of “big data,” by illustrating how we can make compelling visual stories out of the masses of data collected around the world today. Clever and attractive spatial overlays weave new stories – and also save lives.

Dr. Carlos Rodriguéz of Tropenbos International Colombia, and Domingos Muala of Gorongosa National Park, in central Mozambique, drew from their experiences on different sides of the planet listening to stories. In the Colombian Amazon, Rodríguez has spent decades learning from shamans about their relationships with the world around them and sharing these stories – and the stunning visuals members of these same indigenous communities have made to tell their stories to the outside world. In Gorongosa, Muala works with the communities surrounding the park integrate local stories into park practice. The stories these individuals have shared with Muala, such as of their relationships with their totem animals, have been published in his book, Tales from Gorongosa.

Above: Carlos Rodriguéz
Above: Domingos Muala

Everildys Córdoba, the general coordinator of the community of COCOMASUR in northwestern Colombia, closed out the symposium with an important message: we must not only listen to stories, but also support local communities in producing and telling those stories themselves. This process can strengthen communities, build pride in their collective efforts around conservation, and enable them to share their experiences with others interested in similar initiatives. The case study of her community’s experience with REDD+ is available on COCOMASUR’s website.

Above: Lauren Withey and Everildys Córdoba

What might our symposium in Cartagena tell us about storytelling for conservation in Colombia today? The most obvious storyline is one oft told today of Colombia as a land still little explored by “modern science”: a leader of Colombia’s national parks explained, for example, that a new species is “discovered” every time an expedition goes out in the Pacific and Amazonian regions. If we are willing to listen, though, we will also hear the stories of those who have vast, detailed maps of these “unexplored” lands in their minds and hearts, who have intimate knowledge of and close relationships with their flora, fauna, and spirits, and who surely have their own ideas about the future of these lands. And while scientists from around the world are understandably excited to work in Colombia in an improving security context, conservation would benefit greatly by encouraging and supporting Colombians from across the country – equally rich in human diversity – to develop and tell their own stories.

Above: Brashares Lab group members and affiliates with workshop speaker Everildys Córdoba. Left to right: Paul Elson, Jennie Miller, Katherine Siegel, Everildys Córdoba, Lauren Withey, Alex McInturff.

Lab offers perspective on bushmeat hunting for Science

By Kaitlyn Gaynor, PhD Candidate

A child carries a basket containing a Gambian rat and a monkey in Lomela, Democratic Republic of the Congo. The harvest, consumption, and trade of wild meat is central to people’s livelihoods in many countries, yet is also responsible for widespread animal population declines. Photo credit: Lynn Johnson, National Geographic Creative.

In a recent paper in Science, Benítez-López and colleagues synthesize data from around the tropics to distill the impacts of bushmeat hunting into a striking figure: bird and mammal populations decline by 58% and 83% (respectively) as a result of hunting. But what does this number mean for wild animals, their ecosystems, and the human populations that rely on their meat?

As an interdisciplinary research group, we in the Brashares lab embrace and explore the complexity of social-ecological dynamics. Bushmeat hunting and consumption are at the center of a coupled human-natural system in which the health and security of people and ecosystems are tightly linked.

In an accompanying perspective piece in Science, Justin and I bring this interdisciplinary lens to the Benítez-López study to unpack some of the history, drivers, and consequences of hunting and associated defaunation.

Animal behavior key in designating effective wildlife corridors

By Briana Abrahms, PhD ’16

As Earth’s habitats become increasingly fragmented, protecting connections between habitats is critical for sustaining healthy wildlife populations. Our new study in Journal of Animal Ecology reveals that animal behavior is a key component in planning which habitat connections are most essential for wildlife movement.

The establishment of wildlife corridors, swaths of habitat that connect core habitat areas, is a widely popular tool for enabling species to disperse from one area to another. Yet, effective placement of these linkages first requires an accurate understanding of species’ dispersal requirements and habitat preferences. Because dispersal data are often difficult to collect in the field, such connectivity assessments typically rely on the assumption that a habitat occupied by a species is representative of the landscape conditions necessary for its successful dispersal, despite recognition that what habitat an animal uses, or how the animal responds to a particular landscape feature, depends greatly on its behavioral state (e.g. resting, traveling, or feeding).

In our study, we examined the sensitivity of connectivity predictions to behavioral state and tested these predictions against long-distance dispersal movements of African wild dogs, an endangered species highly sensitive to habitat fragmentation. By pairing behavioral data obtained from accelerometers with GPS location data, we measured habitat selection patterns specific to different behavioral states.

We found that wildlife corridors based on habitat preferences when the dogs were traveling protected 87% of long-distance movements, as opposed to only 33% for corridors based on general habitat preferences that did not consider behavioral state. In addition, we reviewed sixteen years of prior connectivity studies and found that most failed to incorporate behavioral information, potentially emphasizing sub-optimal linkages in the landscape.

wildlife corridors based on habitat preferences when the dogs were traveling protected 87% of long-distance movements, as opposed to only 33% for corridors based on general habitat preferences that did not consider behavioral state

The new study highlights the need to account for behavior-specific habitat preferences in conservation and corridor planning. As pressures from changing landscapes and climates continue to rise, effective corridors will become increasingly important for maintaining the viability of Earth’s wild populations.

Read more about the study’s findings in its feature article on Conservation Corridor!

Study shows human illness exacerbates unsustainable fishing practices

By Katie Fiorella, PhD ’15

A toxic environment is known to create health problems for people, but sick people can also create health problems for the environment. Our new research published in PNAS shows that in a fishing community with high rates of disease and declining fish stocks around Kenya’s Lake Victoria, human illness is leader to greater unsustainability in fishing practices.

Read more about the study in articles by UC Berkeley, Cornell, and the National Science Foundation.

Figure 1 from Fiorella et al. 2017

Lab begins research on deer in Hopland, California

By Alex McInturff, PhD Candidate

Sunrise at Hopland.
Sunset at Hopland.








Gorgeous sunrises and sunsets are part of the routine of field work at the Hopland Research and Extension Center in 2017. With the support of the California Department of Fish and Wildlife (CDFW), Justin, Kaitlyn (Ph.D. Candidate) and I have just begun putting GPS collars on deer, whose “crepuscular” behavior makes them most active at dawn and dusk.

These collars provide three streams of information: GPS locations every hour for the next 6 months, GPS locations every 5 seconds for the next month, and data from an accelerometer – more or less a Fitbit for deer – 50 times a second for the next month. Each of these datasets provides unique information on deer movement, resource use, decision-making, fear, and risk. Together, these data help support CDFW efforts to improve deer management and population estimation as well as lab interests in behavior, population dynamics, and species interactions.

And when the rain dries up, the views aren’t too bad either.



Lab members to lead two events at Colombia ICCB in July

By Alex McInturff, PhD Candidate, and Jennie Miller, Postdoc

At this year’s International Congress in Conservation Biology (ICCB) in Cartagena, Colombia, in July, members of the Brashares lab will lead two exciting events.

A symposium, entitled “Conservation and Storytelling in a Post-Truth World,” will aim to expand on these two topics (conservation and storytelling) and broaden the personnel that have been typical of the conference in previous years. A diverse group of speakers from three continents will share their experiences of how storytelling and conservation fit together. Stories have helped broadcast conservation messages beyond academic enclaves; they have helped scientists and practitioners grapple with difficult questions; and finally, as some of our non-academic speakers will share, stories play a major role in shaping landscapes themselves, and thus are more vital than ever to conservationists’ toolkits. Lab leaders Lauren and Alex (Ph.D. Candidates) and a creative team of B-Labmates are organizing this forward-thinking symposium.

The workshop will explain methods and applications of risk models and maps like this one from Miller 2015, showing the likeliness of tiger depredation on livestock.

Jennie (Postdoctoral Scholar) will lead the lab’s second event, a workshop on “Risk Modeling as a Decision-Making Tool for Reducing Human-Wildlife Conflict”. A major challenge in wildlife conservation globally is identifying priority human-wildlife conflict sites where mitigation efforts will be most effective. Spatial risk modeling recently emerged as a tool for understanding, predicting and mapping hotspots of human-wildlife conflict, such as livestock depredation, crop raiding and attacks on people. This workshop will present the methods and applications of spatial risk modeling as a decision-making tool for informing the implementation of conflict mitigation techniques. Jennie will share case studies from India, Mexico and more so look out for tigers, lions and bears!

More information on these events will be posted on the conference website sometime soon. We hope to see you in Cartagena in July!

‘War and wildlife’ article receives media coverage

‘War and wildlife’ article receives media coverage

By Kaitlyn Gaynor, PhD Candidate

Check out the media coverage of our lab’s article “War and wildlife: linking armed conflict to conservation”, published in Frontiers in Ecology and the Environment in December!