For the first time in history, over half the world’s population lives in cities. Urbanization has exploded in the 21st century, and demographers estimate that three quarters of the population will live in urban settings by 2050.
But people aren’t the only ones who are adapting to an increasingly urbanized world. As dense human settlements expand and encroach into natural habitat, more and more animals find themselves living - and in some cases thriving - in the city. A majority of these newcomers are carnivores who, because they can eat anything from mice to garbage, live well in urban environments. The need for more research into how these animals are adapting, including how they interact with people, is growing daily.
Now, Max Planck institute researchers studying a species of carnivores called fishers have devised a new mathematical model based on GPS data that provides a better method of tracking these animals. The study also revealed new insight into how these members of the weasel family are getting around, which includes brave urban explorations.
The scientists outfitted fishers around Albany, N.Y., with GPS sensors, and tracked their movement over three winters. Wildlife biologists typically rely on mathematical modeling to estimate how animals move, so the results of the GPS tracking data have yielded some surprises.
"I was really astonished at how bad the [previous] models were", says Martin Wikelski, a Max Planck Institute for Ornithology researcher said in a statement.
The data showed the fishers were using completely different corridors - routes that animals use to get from place to place - than were previously accounted for. Corridors are a vital area of study in animal conservation because, for example, if a highway is planned across a route that animals use it could endanger an entire population.
Previous mathematical models had only correctly predicted five out of the 23 corridors these carnivores were using. The models were flawed because they relied on information about the habitat preference of the animals. Fishers usually spend their time in forests and avoid open spaces. But that rule didn’t apply here.
“The animals were much more flexible in their willingness to use corridors composed of a variety of habitat types, not just forests,” said Scott LaPoint, a doctoral student who worked on the study.
Instead, they found that fishers use novel ways to get around. For example, instead of trying to cross six-lane highways, the animals went underneath them through old drainage pipes. “I would never have thought it, because with all we know about these shy animals, it didn’t seem possible that they would use such potentially dangerous structures,” said Wikelski.
The researchers are hoping this study can help facilitate more informed urban and landscape planning. To create healthy environments for animals, “we should ask the animals what they need,” said Wikelski, “and by monitoring their movements, in effect we have actually created a way for the animals to communicate with us humans.”
Top image: A fisher with a GPS tracker, courtesy Roland Kays / NC State University.