Северный летяга: описание, ареал и подвиды.

Species of rodent
speciesbox
| image = Glaucomys sabrinus. jpg
| status = LC
| status system = IUCN3.1
| status ref =
| genus = Glaucomys
| species = sabrinus
| authority = (Shaw, 1801)
| subdivision ranks = Subspecies
| subdivision = see text
| range map = Northern flying squirrel Glaucomys sabrinus distribution map. png
| range map caption = Northern flying squirrelrange 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 in the United States. They are light brown with pale underparts and grow to a length of 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 huddle together in a shared nest. Unlike most members of their family, flying squirrels are strictly nocturnal.

The northern flying squirrel is found in coniferous and mixed coniferous forests across the top of North America, from Alaska to Nova Scotia, south to the mountains of North Carolina and Tennessee and west to Utah. The Humboldt's flying squirrel was formerly considered conspecific, but was found to be a cryptic species, and now considered distinct. It is generally smaller and darker than northern flying squirrel and occurs in British Columbia, northern California, Washington and Oregon. Two subspecies are found in the southern Appalachians, the Carolina northern flying squirrel, G. s. coloratus, and the West Virginia northern flying squirrel G. s. fuscus, both of which are endangered, although the West Virginia subspecies has recovered enough that it was delisted in August 2008. G. s. californicus, the San Bernardino flying squirrel, is found in the San Bernardino National Forest in California. In 2010, the Center for Biological Diversity petitioned the U. S. Fish and Wildlife Service to give the San Bernardino flying squirrel protections as an endangered species, but ultimately their request was denied. The U. S. Fish and Wildlife Service said, "in a thorough status review of the species using the best available science, the Service has found that the squirrel is abundant where it is found and that the threats to habitat loss from urban development, habitat fragmentation, wildfire, urban air pollution and climate change do not pose significant threats to its long term survival.”.

These nocturnal, arboreal rodents have thick light brown or cinnamon fur on their upper body and greyish fur on the flanks and whitish fur underneath. They have large eyes and a flat tail. They can also be identified by their long whiskers, common to nocturnal mammals. The adult northern flying squirrel measures from 25 to 37 cm long, and their weight can range from 110 to 230 grams.

Flying squirrels do not actually fly, they glide using a patagium created by a fold of skin. The northern flying squirrel is also known to cache food for when food supplies are lower. These caches can be in cavities in trees, as well as in the squirrels' nest. Lichens and seeds are commonly cached.

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. Nests may also be established in buildings, including parts of occupied homes. 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.

Northern flying squirrels, along with pine squirrels, are an important prey species for the spotted owl (Strix occidentalis) and eastern screech owl (Megascops asio). Unreliable source: date=December 2019 Other predators include various other large birds, especially the great horned owl and hawks, as well as mammals including the American marten, the Canadian lynx, the red fox.