Ecologists measure the impact of humans on wildlife by examining what they have created. Whether it is a hiker traversing a meadow in a distant location, or a vehicle driving through a forest.
A new study reveals that this method has overlooked an important aspect of the human impact.
Human activities are the major cause of biodiversity loss in today’s world. They change climates and alter terrestrial and maritime environments. Understanding how animals and humans coexist in space and behavior is essential for successful wildlife conservation. In the past, researchers have focused on indicators that were more visible such as roads, agriculture, urbanization and energy landscape.
The presence of vehicles and people alone, however, was enough to change animals’ perceptions about risk, their movements, their foraging and socialization. It is difficult to collect fine-scale information on the movement of humans in local environments, so this factor has been overlooked.
Moreover, many studies focused primarily on mammals and paid little attention to other taxa. It is still difficult to understand the synergistic impacts of different human-induced pressures on wildlife. Direct human contact can have a significant impact on the behavior, health and survival of animals.
A new study published in Science on May 21, 2026, analyzed almost 11.8 millions GPS locations of 4581 people from multiple mammal and bird species. The results show that human physical presence alters wildlife habitat usage, regardless of the fact whether the land has been developed, paved or farmed.
More than 65 percent (of the analyzed species) adjusted their degree range, size or spectrum in direct response to human activity.
The fact that they do not only notice us but also where we are located is what makes this finding so striking. Around 60% of species that are sensitive to humans and human activity had interactions between the two. Individuals of species that live in areas with more human development are less likely to respond negatively to humans than those who inhabit landscapes which have been altered little. The animals that live near suburban and farm areas are either accustomed to human presence or have no way out.
The authors state that “Our research demonstrates that, for many species of plants, landscape modifications cannot be fully understood without considering the presence of people, who can both intensify and reduce its effects.”
Researchers took advantage of an exclusive time period from 2019 to 2021, which covered pandemic lockdowns where the movement of humans was dramatically reduced in both developed and non-developed areas. They were able to separate human movement from the long-term changes in landscape, as these two tend to be highly correlated: areas with extensive infrastructure, are also often, at present, places of human activity.
The study used anonymized mobile device counts to monitor daily human presence independent of static development footprints.
Simultaneously and unless otherwise noted, GPS tags were used to track animal movements on a weekly schedule from January through August in both years.
The findings for each species show how wildlife responds to humans in a very complex way. Around 67 percent mammal species reduced their home ranges when humans were present or if landscape modification was occurring. Gray wolves’ ranges expanded as human activity increased, possibly because they are more sensitive to humans and need to stay away from them to capture larger prey.
Coyotes, on the other hand, shrank their ranges as human activity increased: they averaged 11.3 square km per animal, and this decreased each week. Common ravens, a congener of coyotes, had the opposite effect, expanding their home ranges over 26 sq km. They may have been emboldened by the anthropogenic resource that they also utilize, but in a different environment.
Measure the impact of natural disasters on wildlife
The study also looked at “niche sizes”, or the different environmental conditions that animals experience on a weekly basis, from temperatures to types of vegetation. This is a sign that the study was more detailed. In the United States white-tailed deer and other animals that are habituated to humans landscapes, such as those who live in close proximity, grew their range when they were more developed.
However, when people appeared, this niche was reduced. Sandhill cranes showed the exact opposite behavior. They are far less habituated towards humans.
The authors state that “These results show the need to explicitly consider human presence in order to accurately assess anthropogenic effects on wildlife.”
It goes beyond the theoretical to include practical conservation. Conventional planning focuses on land- and habitat-transformation maps, thereby disregarding which areas wildlife are at the highest risk in.
The study revealed an important problem: recreational activities in protected areas with intact forests may disturb resident wildlife to a greater extent than the habitat maps would suggest.
The authors write that the best way to achieve human-wildlife harmony is by minimizing and appreciating human impact.
The soil of city parks contains a surprising amount of wildlife
This study is limited by several factors: It only includes 4,581 birds or mammals large enough to be GPS-tagged, and excludes smaller animals that might behave differently.
It does not prove that a change in behaviour is accompanied by a fitness loss or an adaptive behavior with essentially nil effect. For example, knowing that coyotes shrink their home ranges when humans are present does not tell us whether the behavior has an impact on survival or reproduction.
For answers to these questions we need more information about human activity (e.g.
hikers, hunters, and commuters), as well as data on altered animal movement.
The study shows that, in a wide range of landscapes and species, the tracks of a road are different from those of someone walking in the wilderness, and wildlife pays close attention to both.
Journal Reference
- Oliver, R. Y., Yanco, S. W., Ellis-Soto, D., Jesmer, B.
R., Cohen, J., Gao, S., Patchett, R., Avgar, T., Bildstein, K., Bakner, N. W., Barber, D., Barker, K., Barnes, J. G., Bastille-Rousseau, G., Belant, J. L., Benson, J.
F., Bety, J., Beyer Jr., D. E., Bird, D., Jetz, W. The et all (2026). Effects of landscape modifications and human presence on mammals and birds. Science. DOI: 10.1126/science.adq3396
