For thousands of years, humans have transformed natural landscapes and adapted wild animals to cities, farms, roads, and other human-dominated environments. New research shows that wildlife responds not only to these changes, but also to the direct presence of people nearby.
Researchers from the University of California, Santa Barbara, the Smithsonian’s National Zoo and Conservation Biology Institute, and Yale University combined GPS tracking data from 37 animal species with anonymized mobile phone location data collected across the United States. The study found that wildlife responses to human activity vary widely by species and depend on how extensively the surrounding landscape has already been modified. These findings could help scientists develop more targeted wildlife management and conservation strategies.
“Humans have complex impacts on wildlife, from their physical presence to the way they reshape habitat, and we cannot fully understand our impacts without information about both,” said co-lead author Ruth Oliver, an assistant professor at UCSB’s Bren School of Environmental Science and Management.
COVID-19 lockdowns created a rare opportunity to study wildlife behavior
COVID-19 lockdown policies dramatically changed where and how people traveled. This unusual shift allowed researchers to separate the effects of human presence from the long-term effects of permanent landscape changes.
The research team analyzed weekly GPS records from 4,581 mammals and birds across the continental United States during 2019 and 2020. While animal movements could be tracked with relative ease, determining where people were located required a more detailed source of data than scientists typically have access to.
Reliable public data on human movement is difficult to obtain. As a result, studies of human-wildlife interactions often use indirect indicators such as urban development, agriculture, or COVID-19 lockdown status. Although these measures offer clues about human activity, they do not directly show where and when people are moving.
To address this limitation, the researchers used anonymized mobile phone geolocation data with neighborhood-level resolution. According to the team, this is the first study to use this type of information to examine how human presence affects animal movement.
“The cell phone data we used was made available to researchers during the pandemic to uncover the effects of COVID-19 closures,” said co-lead author Scott Janko, a research ecologist at the Smithsonian’s National Zoo. “This was a unique opportunity to measure how human presence affects wildlife and demonstrate that land modification is not the only factor conservation planners need to consider.”
Human presence and habitat modification influence wildlife together
The researchers examined how human activity affected both the physical area occupied by each animal and its environmental niche—the combination of habitat conditions and resources it uses. For most species in the study, landscape modification alone did not fully explain the effects of human activity. The presence of people also played an important role.
Overall, 57% of the species studied responded to both human presence and landscape modification. Human presence was associated with changes in territory size or environmental niche size in 67% of mammals and 68% of birds.
In many cases, these two influences were interconnected. The effect of human activity on wildlife partly depended on how extensively the surrounding landscape had already been altered. At the same time, the effect of landscape modification depended partly on how many people were present.
Approximately 67% of mammals and 41% of birds responded to the combination of human presence and landscape change by using less habitat. Wildlife sensitivity to people was especially strong in less developed areas, including national parks, compared with urban environments.
Wolves, deer, and cranes show different responses to people
There was no single response shared by all wildlife species. Wolves, for example, behaved differently from many of the other animals studied. Their habitat use expanded in response to human activity, potentially reflecting their long history of conflict with people and conservation efforts to relocate or expand wolf populations away from human development.
White-tailed deer showed another distinct pattern. Their environmental niche expanded as the landscape became more modified but contracted as human presence increased. Sandhill cranes displayed the opposite response.
“These discoveries highlight the critical importance of species-based conservation,” Oliver said. “Every species has different habitat requirements, behavioral tendencies, and threats. Effective conservation depends on understanding the specific challenges faced by each species.”
What the global “human hiatus” revealed about wildlife
The study is part of the COVID-19 Biologging Initiative, an international effort created to examine how wildlife responded when human activity changed dramatically during pandemic restrictions. Researchers referred to this unusual period as the “human hiatus.”
Previous research from the initiative has documented widespread behavioral changes in mammals around the world, major shifts in ocean traffic, and the importance of directly measuring human movement when studying wildlife during the Anthropocene—a period in which human activity has significantly affected Earth’s environment.
The international collaboration involved 600 partners and collected 1 billion location records from nearly 13,000 animals to investigate how human activities affect wildlife.
The new findings show how animal GPS tracking and mobile device data can improve conservation planning. By combining the two data sources, researchers can distinguish between the effects of human-built infrastructure and the effects of people simply being present.
Do human-driven behavioral changes help or harm wildlife?
Oliver and her colleagues are now investigating whether changes in animal behavior caused by human activity and climate change affect wildlife survival.
“Our current research shows that animals change the way they use space and resources, but we do not know whether these changes are helping animals adapt or are signs of stress,” Oliver said. “Our group is now examining whether animals that alter their behavior in response to human pressure face a higher or lower risk of death.”
The unusual circumstances of the pandemic gave researchers an opportunity to study wildlife responses in ways that were previously difficult or impossible. These findings could help improve conservation policies by providing more detailed information about how animals respond to human presence.
“Our results give us optimism that wildlife coexistence can be achieved through more nuanced policies that consider more carefully where and when animals need space,” Oliver said.
Ben Marcus of the Smithsonian Institution contributed to this article.
Source: www.sciencedaily.com