Refuge Notebook: Myth or mystery — flying squirrels on the Kenai

The northern flying squirrel (Glaucomys sabrinus) is somewhat of an enigma to the Kenai Peninsula. While it has an established home in the Interior and Southeast Alaska, it has only been reportedly seen in our neck of the woods.

Refuge Notebook readers may recall a 2010 article, “Evidence of Flying Squirrels on the Kenai Peninsula? It is Debatable!” in which refuge biologist Dawn Magness analyzed a photo taken via a camera trap near Funny River.

Having worked with flying squirrels in Southeast Alaska, Dawn believed this photo to be proof of their presence on the Kenai. This photo evidence, along with possible evidence of a foraging flying squirrel noted in a 2001 Refuge Notebook article, may have had us convinced, but ultimately, to be sure, we need more evidence.

Documenting this species presence has been a challenge. Northern flying squirrels have evaded additional conclusive or concrete findings on the Kenai despite an abundance of their preferred habitat and resources. They like a mosaic of old forests and coniferous riparian zones and have similar diets to those of our red squirrels.

This leaves us with a few questions. Are they here? If not, why? And why does this matter?

When asking these kinds of questions, it is important to understand the organism’s biogeography: essentially, why they are where they are. We can look at an organism’s movement over geological time and what we know of their life history to determine exactly why they occur, in Alaska, but not in Antarctica.

Starting in the late Miocene, 11.6 to 5.3 million years ago, the squirrel family (Sciuridae) originated in Asia. Flying squirrels then diverged from tree squirrels in the late Miocene. Flying squirrels in the New World, which refers to the Western Hemisphere and the Americas, most likely dispersed over the Bering Strait land bridge.

From there, they continued to distribute along the Pacific Coast and interiorly across North America. They may have been in isolated forests during the last glacial maximum, which occurred 75,000 to 11,000 years ago. As the glaciers retreated north, so did our flying squirrels along with many other species of plants and animals. Alaska’s forested areas eventually became the most northern and western boundary of the northern flying squirrel’s range.

Today, there are established populations of six different subspecies of flying squirrels throughout the Interior and Southeast regions of the state. Found in the Interior, the northern flying squirrel, belonging to the subspecies Yukonensis, is the most widespread. If flying squirrels are here, the Yokonesis would be the subspecies most likely to be found on the Kenai Peninsula.

Flying squirrels, whatever the species, are categorized by their characteristic patagium (gliding membrane), large eyes and thick, brown fur. Northern flying squirrels have a gray underbelly and tend to be larger than their close relatives, the southern flying squirrel (Glaucomys volans), which have a white or cream-colored underbelly.

Both northern and southern flying squirrels require forests that have trees spaced close enough to allow gliding and protection from predators. They nest in tree cavities or abandoned nests of other animals. The northern flying squirrel, however, may prefer forests dominated by conifers like spruce and hemlocks. While the southern flying squirrel prefers deciduous and mixed forests that include oaks and poplars. It is thought that flying squirrels have an omnivorous diet that largely resembles the more familiar tree squirrel—eating fungi, nuts, seeds, fruit, various vegetation, and even meat (including carrion).

The Kenai Peninsula checks all boxes for habitat requirements (old forests, riparian areas, food resources) of the flying squirrel. Based on movements documented over geological time and considering the proximity to their known range, the Kenai is in a prime area for dispersal. Yet, they continue to elude sightings.

There may be two possibilities: they are here but have managed to stay well-hidden or are not here due to a possible barrier to dispersal.

A mountainous isthmus, the nine-mile-wide thread of land in which the Kenai Peninsula connects to mainland Alaska, may be an obstacle to dispersal. Isthmi like these tend to create island-like effects in that populations on either side cannot move along the landscape, leading to a degree of isolation.

In a more abstract sense, competition can be a barrier as well. Something to take into consideration is the similar diets of flying squirrels and tree squirrels. The Kenai has an abundance of red squirrels, which may be out-competing the flying squirrel for food resources. In this instance, it is possible that flying squirrels may have made an appearance but failed to establish a population.

If the flying squirrels could conquer these obstacles and disperse to the Kenai, we may still not catch sight of them. Combined with the general elusiveness of most small mammals, flying squirrels are nocturnal and are only active for an hour or so at a time. It is no wonder the flying squirrel are challenging to observe, but biologists at Kenai National Wildlife Refuge hope to catch them in action. Using a non-invasive camera trap set high in trees, biologists aim to acquire those coveted concrete findings.

You may be wondering, “Why does this matter? Sure, they are cute, but what difference does it make to have evidence they are here?” Documenting their presence could help refuge biologists understand the natural diversity of species, the amount and variation of organisms that ultimately lead to a healthy, productive, and functional habitat or ecosystem to help us conserve this enigma, especially during these times of rapid environmental change.

Finding flying squirrels on the Kenai Peninsula would mean they could be considered in management decisions, too. They are endangered in some areas, and knowing they are here could mean helping them, and in turn, the refuge, to thrive. If you have a possible sighting, call our refuge headquarters to let us know!

Angelica Smith is a biology intern this season at Kenai National Wildlife Refuge. She is an aspiring wildlife biologist with hopes to complete research that creates impact and leads to policy change. Intrigued by this article, learn more about flying squirrels from these past Refuge Notebook articles:


Kenai National Wildlife Refuge