The squirrels that scamper across back yards, parks and undeveloped areas, searching for food or finding it in your bird feeder are gray squirrels, not the native Western gray squirrels but the invasive Eastern gray squirrels.
The native gray squirrel population now survives in three geographic pockets in Washington state, the population ranging from a few hundred in one area to a few thousand in the other two.
“They were much more widespread than today. Now we have three populations: east side of the North Cascades, Chelan and Okanogan counties; Pierce County, the Puget Trough near Joint Base Lewis-McChord; and Klickitat, Yakima and Skamania counties,” said Penny Becker, the state Department of Fish and Wildlife’s listing and recovery section manager.
“Historically, they would have been linked, but over time, the habitat has changed. The major threat is land conversion: urbanization, building roads, logging, trees cut down for grazing. They need an intact transitional stage of forest with Oregon white oak, Doug firs and riparian tree species,” she said.
Genetically isolated, two of the locations already may be suffering from genetic inbreeding.
The Eastern gray squirrels are more ubiquitous and aggressive, although smaller.
“Where they overlap, it competes better than the Western, even though it’s smaller. It’s able to live in different environments, back yards, around people,” she said.
As part of its population research, hair tubes with bait are distributed, and hair collected for its genetics so that squirrels can be identified as Western or Eastern, Becker said.
Western gray squirrels found in the forests use the Oregon white oak and Douglas fir woodlands of the Puget Trough; white oak and ponderosa pine in south-central Washington; and the mostly grand fir and Douglas fir zone in Chelan and Okanogan counties.
Oak mast (acorns) are essential to their food intake and are a critical winter food. Western gray squirrels also eat underground fungi, green conifer cones, and seeds, other nuts and vegetation.
The native squirrels play an important part in maintaining oak woodlands by planting acorns to be eaten later and spreading spores of mycorrhizal fungi that aid tree growth.
The best-case scenario for the native squirrels: moderately close tree canopy for travel, acorn-bearing trees, large trees, and proximity to water.
Factors that threaten the population include habitat loss and conversion to meet human needs; fluctuating food supplies, disease, death by car and illegal shooting.
Once Western gray squirrels were hunted here, but have been protected since 1944 and listed as threatened since 1993.
A combination of studies by the Fish and Wildlife Department, university researchers and citizen-scientists continues to gather information that may create a path to stabilizing and even increasing the native population.
“Western gray squirrels occupy a niche that can tell us a lot about the current state of a forest. If we lose gray squirrels, it’s an indication that the forest systems aren’t functioning correctly,” Becker said.
There are no signs of population recovery.
Columnist Sharon Wootton can be reached at 360-468-3964 or www.songandword.com.
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