Mammals in Hartley Park range from our occasionally seen bear and fox and frequently seen deer, to much rarer species, including ermine, fisher, otter, pine marten, and coyote. Small mammals, such as mice, shrews, squirrels, and chipmunks abound. Ecologically, mammals serve as excellent indicators of food-chain dynamics, especially in urban environments, where sightings are much more rare and encounters often occur only by the side of the road or beneath the tires. For these reasons, diligent data management and utilization of GIS mapping technologies are all the more important for their study, as long-term tracking may help guide our maintenance and policies within the park.