page_title: Northern flying squirrel
section_title: Behaviour
hierarchical_section_title: Northern flying squirrel / Behaviour
caption_attribution_description: The Carolina northern flying squirrel is a cold-weather animal descendent from the northern flying squirrels pushed south by the ice sheets that covered northern latitudes during the last ice age. When the ice sheets receded, some of these squirrels found refuge on the tops of our highest mountains. Over the millennia, these squirrels differentiated from their northern cousins and today are a subspecies found only in the Southern Appalachians where northern hardwood forests give way to spruce-fir forests. One of the main ways biologists track populations of these squirrels is to provide nesting boxes, mounted high in trees, which are periodically checked to see if they’re occupied. If Carolina northern-flying squirrels are found using the boxes, those individuals are tagged, weighed and measured. On this day, the Service’s Sue Cameron joined Dottie Brown of the N.C. Wildlife Resources Commission to check a series of boxes off the Blue Ridge Parkway. Unfortunately no squirrels were found on this snowy day, but the trip provided the biologists an opportunity to replace degraded nest boxes.
context_page_description: The northern flying squirrel is one of three species of the genus Glaucomys, the only flying squirrels found in North America. They are found in coniferous and mixed coniferous forests across much of Canada, from Alaska to Nova Scotia, and south to the mountains of North Carolina and west to Utah, Washington, and Oregon in the United States. They are light brown with pale underparts and grow to a length of 25 to 37 cm. They are proficient gliders but uncoordinated walkers on the ground. They feed on a variety of plant material as well as tree sap, fungi, insects, carrion, bird eggs and nestlings. They mostly breed once a year in a cavity lined with lichen or other soft material. Except when they have young, they change nests frequently, and in winter a number of individuals may snuggle together in a shared nest. Unlike most members of their family, flying squirrels are strictly nocturnal.
context_section_description: Northern flying squirrels generally nest in holes in trees, preferring large-diameter trunks and dead trees, and will also build outside leaf nests called dreys and will also nest underground. Tree cavities created by woodpeckers as suitable nest sites tend to be more abundant in old-growth forests, and so do the squirrels, though harvested forests can be managed in ways that are likely to increase squirrel numbers. Except when rearing young, the squirrels shift from nest to nest frequently. They often share nests during winter months, forming aggregations. Usually, aggregate nests contain 4 to 10 individuals. The sharing of nests in winter by northern flying squirrels is important in maintaining body temperature (biothermal regulation), as northern flying squirrels do not hibernate, nor do they enter torpor states.
  Northern flying squirrels gliding distances tend to be between 5 and 25 metres, though glides of up to 45 m and longer have been observed. Average glides are about 5 m less for females than for males. Glide angle has been measured at 26.8 degrees and glide ratio at 1.98.
  Since first documented by Shaw in 1801, the general understanding was that northern flying squirrels bred but once per year. Recently, in southern Ontario, Canada, polyestrous behaviour (two litters per year) has been documented for the first time. This observation has since been confirmed by a second research team in New Brunswick, Canada.
  In southern Ontario, Canada, genetic evidence has recently shown hybridization with the rapid northward expansion and increased sympatry of southern flying squirrels.
caption: Installation of a new squirrel box off the Blue Ridge Parkway
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