Mammals represent a fun clade of organisms. You and I belong to this group mostly due to our fur and babies, though scientifically it has more to do with the shape of our skulls. This, among a litany of other reasons, is why a coconut is not a mammal despite its fur and milk. We belong to a group of animals called synapsids, a linage dating back to over 300 million years when the first members of this group evolved holes in their skulls behind their eyes, letting all of our relatives bite down with a good deal of force. Mammals are tremendously good at just about everything, a key factor to why they are the dominant terrestrial group in many ecosystems today. There are the highly successful generalists like mice, deer, skunk, raccoons, and, of course, humans. There are also highly specialized niche mammals that perform key roles in our ecosystem: Seed broadcasters (squirrels that bury the many varieties of nuts), pest control (bats eating their weight in mosquitos a night), habitat management and construction (beavers creating dams and lodges), and many more! The Pennsylvania Game Commission oversees the protection, management, and largely the education about the mammals in Pennsylvania, everything from chipmunks to black bears. The game commission maintains a series of informative “wildlife notes” on many of the wild mammal species. These notes are worth diving into to learn about some of the more unique ways these furry friends contribute to our natural surroundings.
When out exploring it is easiest to classify mammals based on the habitat you find them in. While some of the generalist species mentioned above can be found across every biome in Pennsylvania, many are more selective. For example, you are unlikely to see a fisher, a relative of the weasel, anywhere other than an older forest with significant woody debris.
A keen-eyed observer walking through some of the denser forests in our area might be fortunate enough to spot a bobcat, porcupine, or fisher. Fishers are one of the few direct predators of porcupines, so it is fitting that they would be found in similar habitats. Bobcats are equal parts house cat and feline fury though you are unlikely to see one. They are very difficult to find and prefer to skulk about secretively, but the best places to find them are near new timber cuts or other areas that have experienced a recent increase in small mammals. Poe Paddy, Alan Seeger, and the Spring Creek Canyon all offer the types of woodland habitat you might expect these mammals to prowl.
Venturing forth into more open terrain on the edges of larger woods brings the most opportunities to see the widest varieties of mammalian wildlife. Almost all of the smaller mammals like mice, voles, and shrews exist in the transitional area as their wide array of food sources are plentiful as is their ability to find shelter. These tiny taxa make up the majority of the mammal species in Pennsylvania. Despite intense pressure form predators in this edge habitats their breeding rates keep their population levels stable where other, less prolific species would not be able to survive. Mount Nittany, Millbrook Marsh, Colyer Lake, and the Barrens to Bald Eagle Wildlife Corridor are great places to explore these areas along the border of forests and open areas.
The Pennsylvania Mammal Atlas is a citizen science group that can help identify mysterious mammals. Additionally members can submit reports, including pictures and sightings that can help researchers discover new things about these critters. The main goal of this project is to better create population distribution maps as well as track changes over time, a very important task as climate change can drastically alter the home ranges of species causing increased completion for resources and potentially damaging diversity.