Mammals move shorter distances in human-altered landscapes, UM study finds

Research conducted by a team of biologists, including a University of Montana professor, found that mammals move shorter distances in human-modified landscapes, something that could affect the function of ecosystems that depend upon the movement of the species within it.

The study was published last month in the journal Science.

“Our data showed reduced movements of species like wolves and elk in areas with high human footprints,” said UM biologist Mark Hebblewhite, who coauthored the study.

“Here in Montana, we're concerned about loss of long-distance movements, like migration for elk because of agricultural subsidies. Loss of migration is bad for ranchers and for elk. Migration helps maintain higher numbers of elk and reduces conflicts with humans.”

Most mammals are on the move every day while searching for food, mates or shelter. Some larger mammals, like wolves, generally move longer distances while smaller mammals, such as hares, usually cover shorter distances.

Led by biologist Marlee Tucker, researchers found that the extent of movement is reduced in human-altered landscapes when compared to animals living in wilder, more natural settings. The study included movement data collected from 803 individual animals across 57 mammal species ranging in size from rodents to elephants.

In their study, researchers tracked the movement by GPS and recorded the results for a period of two months. The data was then compared to the human footprint in the same locations. The resulting index measured how much an area has been changed by human activities, such as infrastructure, settlements or agriculture.

Tucker said the study also accounted for habitat productivity using NASA-derived measures of habitat productivity. The researchers believe that reduced travel distances could affect ecosystem functions that depend upon the movement of animals.

“It's important that animals move, because in moving they carry out important ecological functions like transporting nutrients and seeds between different areas,” Tucker said. “Additionally, mammalian movements bring different species together and thus allow for interactions in food webs that might otherwise not occur. If mammals move less this could alter any of these ecosystem functions.”