Plate Nº 28 · recorded September 29, 2026
Biology & EvolutionReported finding
Tracking 4,581 Animals Reveals a Hidden Human Effect on Wildlife
GPS data from thousands of mammals and birds paired with cellphone location records shows animals respond to people being nearby — often as strongly as to habitat change itself.
By Elena Vasquez4 min read850 words
In brief
- Researchers tracked 4,581 mammals and birds across the continental U.S. during 2019 and 2020.
- 57% of studied species responded to both human presence and landscape modification.
- This is the first study to use anonymized cellphone geolocation data to measure how human presence affects animal movement.
People have reshaped the natural world for millennia, pushing wildlife to adapt to cities, farms, and roads. But a new study published in Science suggests something more surprising: animals respond not only to the environments we build, but also to the simple fact that we are physically nearby — and sometimes just as strongly.
Researchers from UC Santa Barbara, the Smithsonian's National Zoo and Conservation Biology Institute, and Yale University combined GPS tracking data from 37 animal species with anonymized cellphone location data from across the United States. The findings show that wildlife reacts to human presence in strikingly different ways depending on the species and on how much the surrounding landscape has already been altered. Those differences, the authors argue, call for far more targeted conservation strategies.
"Humans have complicated effects on wildlife — from our physical presence to how we reshape habitats — but we can't understand our full impact without information on both," said co-lead author Ruth Oliver, an assistant professor at UCSB's Bren School of Environmental Science & Management.
A pandemic-sized natural experiment
The COVID-19 lockdowns created a rare scientific opportunity. When pandemic policies suddenly changed where and how people moved, researchers could, for the first time, cleanly separate the influence of human presence from the permanent effects of roads, buildings, and farmland.
The team analyzed weekly GPS records from 4,581 individual mammals and birds across the continental U.S. during matching periods in 2019 and 2020. Measuring animal movement was the easy part. Pinning down exactly where people were proved harder, because precise public data on human movement is rarely available to scientists. Studies of human-wildlife interactions usually rely on indirect proxies — the extent of urban development, agriculture, or whether an area was under lockdown.
To get around this, the researchers turned to anonymized cellphone geolocation data with neighborhood-level resolution, which private companies had released to researchers during the pandemic. According to the team, this is the first time such data has been used to study how human presence affects animal movement.
"Typically, private companies hold onto these, which made this a rare opportunity for us to quantify how human presence impacts wildlife, and to demonstrate that there is more to consider than just land modification to create robust conservation plans," said co-lead author Scott Yanco, a research ecologist at the Smithsonian's National Zoo.
Presence and pavement work together
The researchers looked at two measures: the physical area each animal used, and its environmental niche — a term describing how an animal uses habitats and resources. For most species, landscape modification alone could not explain the observed changes. People mattered too.
The numbers are striking. Human presence was associated with changes in territory size or niche breadth for 67% of mammal species and 68% of bird species. Overall, 57% of species were affected by both human presence and landscape modification combined. The two forces were intertwined: the effect of people on an animal depended partly on how developed the surrounding landscape was, and vice versa.
Roughly 67% of mammal species and 41% of bird species responded to the combination by shrinking the amount of habitat they used. Sensitivity to people was especially pronounced in places with little development — national parks, for instance, compared with cities.
Wolves, deer, and cranes tell different stories
There was no single pattern. Wolves actually expanded their habitat use in response to humans, possibly reflecting their long, fraught history with people and an effort to move farther from human activity. White-tailed deer showed the opposite trend in one sense: their environmental niches grew as landscapes became more modified, but contracted as human presence increased. Sandhill cranes displayed the reverse of the deer's response.
"These findings highlight the critical importance of species-based conservation," Oliver said. "Every species has different habitat requirements, has its own behavioral tendencies and faces unique threats."
The bigger picture — and the open question
The study forms part of the COVID-19 Bio-Logging Initiative, an international project studying how wildlife responded during what researchers call the "anthropause" — the unusual pause in human activity caused by pandemic restrictions. The broader collaboration involved 600 partners and compiled roughly 1 billion location records from about 13,000 animals.
One crucial question remains unanswered. "Our current study shows that animals change how they use space and resources, but we don't know if these changes are helping them adapt or are a sign of stress," Oliver explained. Her group is now investigating whether animals that alter their behavior under human pressure face a higher or lower risk of dying.
The results suggest conservation policy can become more refined by distinguishing between the footprint of human infrastructure and the effect of people simply being present. "Our results give me some optimism that we can achieve wildlife-coexistence through more nuanced policies that more smartly consider where and when we need to give animals space," Oliver said.
Because earlier policies were developed without this kind of detailed information, the findings may prompt a rethink of how, where, and when humans give wildlife room to move.
via news.ucsb.edu (Original)