ST. LOUIS — A new study led by researchers from Saint Louis University, the Saint Louis Zoo, and partner organizations set out to understand how raccoons use space in one of the nation's largest urban parks. The study, published in the Journal of Mammalogy , found that raccoons living in the 1,326-acre Forest Park in St. Louis avoid roadways, even when incentivized by open food sources.
Using GPS-VHF collars with tiny tri-axial accelerometers (devices that track motion in three-dimensional space), researchers followed 10 raccoons living in Forest Park between 2021 and 2024. The sensors revealed animal movements and behavior across seasons. As expected, most raccoons stayed within Forest Park boundaries, maintaining relatively small home ranges. Only one especially bold individual made regular trips outside the park, primarily for dumpster diving.
Researchers found that the raccoons avoided crossing roads, even when thoroughfares were lined with trash cans and other discarded food sources. After comparing the animals' actual patterns with thousands of simulated paths, the results were clear: raccoons cross roads less than expected. These cautious behaviors suggest that roads pose enough risk to directly influence how the animals navigate their space.
Accelerometer data also showed how environmental conditions affect raccoon activity. As expected, the animals were most active at night, with peaks around dawn and dusk. The raccoons' movement also increased on warmer days. Researchers found that on short, summer nights the animals "made up" for fewer hours of darkness by being more active per hour, packing in extra movement during limited nighttime windows.
Together, these findings show how urban wildlife adapts its behavior to external factors. By researching how urban animals traverse natural and urban environments, researchers hope to better understand how humans can successfully share space with wildlife. The Saint Louis Zoo is also a contributing member of the Forest Park Living Lab, a collaborative effort tracking the health, movement, and interactions of more than 15 species in the park.
This research was funded by the Living Earth Collaborative at Washington University in St. Louis, the Saint Louis Zoo Institute for Conservation Medicine, the Saint Louis University Biology Department, the Taylor Geospatial Institute, and the National Great Rivers Research and Education Center.
About Saint Louis University
Founded in 1818, Saint Louis University is one of the nation's oldest and most prestigious Catholic research institutions. Rooted in Jesuit values and its pioneering history as the first university west of the Mississippi River, SLU offers more than 13,300 students a rigorous, transformative education that challenges and prepares them to make the world a better place. As a nationally recognized leader in research and innovation, SLU is an R1 research university, advancing groundbreaking, life-changing discoveries that promote the greater good.
