Monitoring Western Gray Squirrels for Landscape Management in Western Washington

Western gray squirrels (Sciurus griseus griseus Ord) are rare in western Washington and population distribution information has proven difficult to gather. A variety of standard survey methods employed on the Fort Lewis Military Reservation in southern Puget Sound in 1998-99 yielded limited results, likely due to the squirrel’s elusive behavior and low-density population. We tried a new survey approach in 2004 using hair-snare tubes, which proved successful in providing information on the distribution of habitat used by western gray squirrels and eastern gray squirrels, the latter previously unknown to be resident in the interior woodlands. The hair-snare tubes also contributed information on habitat use by western and eastern gray squirrels during management actions such as timber cutting and eastern gray squirrel trapping. Knowledge of squirrel distribution allowed managers to strategically allocate resources to improve habitat. Hair-snare tubes are relatively inexpensive to construct and easy to install, and have the potential to provide distribution information on squirrel populations that are widely distributed or occur at low densities, and difficult to detect visually. At the same time, interpretation of results obtained from hair-snare devices are constrained by unknowns regarding numbers of individuals depositing hair samples, and inter- and intra-specific behavioral interactions that influence hair deposition patterns. Despite the drawbacks, knowledge gained from hair-snares can serve as a basis for management planning and lead to the application of other direct study techniques, such as radio-telemetry, that are likely to yield more detailed information.