Mahan and her colleagues are still working out the pieces of this complex puzzle. When you lose hemlocks, stream temperatures increase and you lose brook trout." "Conifers provide habitat for many other species," Mahan continues. Without the northern squirrel, there are fewer fungi, and that means added stress on an already weakened population of trees. It goes back to that finicky diet: By eating all those truffle-like fungi, Mahan explains, and disseminating the spores through their scat, "in effect these squirrels are seeding the conifer stands with fungi." The trees, in turn, rely on the fungi to help them absorb nutrients and moisture. But the fact is that where the two species intermingle, the Northern one tends to wind up dead-and when we autopsy them many are infected with Strongyloides."Īs the northern squirrels decline, she notes, an important role in the ecosystem goes unfilled. "The evidence is circumstantial right now. "It's not that the southern squirrel is pushing out the northern one directly," Mahan explains. That means trouble for the northern squirrel, she says, because the southern variety carries an intestinal parasite, Strongyloides robustus, which is apparently lethal to its northern cousin.īiologists call it indirect competition. In addition to shrinking the northern squirrel's habitat, Mahan says, fragmentation has brought northern and southern squirrels into close contact. Development is carving up forest land, and a warming climate has benefited heat-loving pests like the woolly adelgid, an invasive sap-sucking insect now eating its way through the state's hemlocks. Unfortunately, the number of unbroken conifer stands in Penn's Woods is dwindling. And while it certainly munches its share of nuts and seeds, its favorite food is the truffle-like fungi that grow beneath red spruce and hemlock. It prefers the heavy cover of coniferous forests. The Northern flying squirrel, native to Canada and as far south as the northern Appalachians, is a bit more finicky. Its overall hardiness, in fact, has made it "probably Pennsylvania's most common squirrel"-more common even than the ubiquitous gray. It can live almost anywhere, including in household attics, says Mahan, associate professor of biology at Penn State Altoona. from Vermont to Florida, is a traditional mast eater, chowing down on a steady diet of seeds and fruits. The Southern flying squirrel, found all over the eastern U.S. Yet the Southern takeover could have significant impact on forest ecology.įor all their similarity, Carolyn Mahan explains, the two squirrels like different habitats, and different foods. Most of us would be hard pressed to notice the transformation: These two aerobatic species are strictly nocturnal, and so nearly identical it takes a trained eye to tell them apart. Southern flying squirrels are taking over. It spends more time foraging on ground than the southern flying squirrel.Northern flying squirrels are rapidly disappearing from Pennsylvania forests. They can survive on a diet of lichens and fungi, and may thus be less dependent on seeds and nuts than G. In the winter, this species feeds from caches in crevices, crotches of trees. This species often lives near streams and rivers.
This subspecies is typically found in conifer-hardwood ecotones or mosaics consisting of mature beech, yellow birch, sugar maple, hemlock, and black cherry associated with red spruce and balsam or Fraser fir. South of Pennsylvania, this species occurs in small, isolated, relict populations at high altitudes. sabrinus fuscus has been confirmed in Highland and Montgomery Counties from capture data. There has been a major push since being declared endangered leading to nest box placement in 10 counties of western and southwestern Virginia. They are on the verge of extirpation in Virginia. The voice is high-pitched insect-like chirps. They are nocturnal, usually active even in the severest winter weather. One litter of 2-4 young are born in May and June each year.
This species usually lives in small family groups in nests in tree holes, and old bird nests. The eyes are prominent, large and blackish. The tail is broad, horizontally flattened, and there are membranes (patagia) between the fore and hind legs. volans, with a browner dorsal pelage, distinguished by the belly hairs being slate-colored at the bases,the coat is dense, soft and the sides grayish-brown, sometimes washed with cinnamon. ( Glaucomys sabrinus fuscus) Characteristics
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