Humboldt Flying Squirrel

Monitoring Humboldt’s Flying Squirrel with Novel Techniques (2019 – $1,032)

Barbara Clucas – Assistant Professor in Wildlife, Humboldt State University

The Humboldt’s flying squirrel (Glaucomys oregonensis) is a newly described species of flying squirrel in North America. This species was previously thought to be part of the geographically widespread Northern flying squirrel (Glaucomys sabrinus) but recent molecular studies show that flying squirrels in California up to Washington are a distinct species. Flying squirrels are nocturnal, cryptic animals that are ecologically important. In California and the Pacific Northwest, flying squirrels are important prey species for Northern spotted owls (Strix occidentalis caurina) and fishers (Martes pennanti), which are species of conservation concern. Flying squirrels also play a role in mycorrhizae dispersal (i.e., fungal spore dispersal such as truffles), which is important for growth in young trees, forming a symbiotic relationship among the squirrels, fungi and trees. Therefore an understanding of the distribution, abundance and behavior of the Humboldt’s flying squirrel is a key conservation issue in northern California.

Flying squirrels can be difficult to monitor and study in the wild due to their cryptic nature and difficulty in trapping. Several studies have shown that camera traps are a reliable, cost-effective, and safe method to monitor Northern flying squirrels and Japanese flying squirrels (Pteromys momonga). Furthermore, Northern flying squirrels and Southern flying squirrels (Glaucomys volans) have recently been discovered to produce ultrasonic vocalizations (like bats) and researchers in the Eastern United States have found that ultrasonic recorders used for recording and monitoring bats can be used to record these squirrel vocalizations in the wild.

A conservation grant from Sequoia Park Zoo will help purchase camera traps to further investigate methods to monitor flying squirrels and to be able to determine their annual activity patterns (i.e., when they are most active throughout the year) in Headwaters Forest Reserve and Arcata Community Forest. In addition, recordings of their calls will be made to
capture their full repertoire with the ultimate objective of creating a comprehensive call library that can be used for acoustic monitoring of these cryptic species. Another objective of this project is to give undergraduate students at Humboldt State University the opportunity to gain research and field experience. The proposed Humboldt’s flying squirrel project has the capacity to engage many students both in the field and lab.

The ability to monitor Humboldt’s flying squirrels will be important for the conservation of fisher and Northern spotted owls that prey on this squirrel species. More broadly, establishing standardized methods to detect and monitor flying squirrels will be useful for assessing the ecosystem health of redwood forests as they have been found to have a symbiotic relationship with fungi and trees. In addition, flying squirrels are a biologically unique species that are charismatic and can engage the public and increase interest in conservation and scientific research.