About

Tree Squirrels of California

Our Mission

Tree Squirrels of California - (T.S.O.C) helps people understand and protect the state’s two native tree squirrels—the Western Gray and Douglas squirrels—and offers guidance on how to live responsibly with the two introduced species. Through squirrel ID tools, habitat awareness, and citizen science, we guide California’s squirrel friends and foes alike toward better choices and peaceful coexistence.


Some people adore squirrels.

Some... don’t. Let’s break it down.

Tree Squirrel Love?

  • Delightful to watch, film and photograph
  • Plant trees by forgetting buried acorns
  • Help forests thrive by dispersing seeds and fungi
  • They teach us about ecosystems and wildlife intelligence
  • They’re just plain cute!

Tree Squirrel Woes?

  • Digging up plants in gardens
  • Chewing on wires, nesting in buildings and stripping tree bark
  • Raiding bird feeders and picnic tables
  • Non-natives threaten native squirrels and other native wildlife
  • They sometimes carry parasites or disease

Western gray squirrel in redwood sprouts
Young Western Gray in the Redwoods

Our Concern

T.S.O.C was founded to help people understand squirrels better regardless of their point of view. It’s helpful to know what you can do about squirrels if they are causing damage. Squirrels are playful, cute and intelligent, but also can be highly destructive and can carry diseases that affect humans.

Many pest control websites do a great job of explaining removal options, but it’s complicated because the laws vary with different types of squirrels. Studies show that human activities play a big role in allowing squirrels to cause damage in the first place. In many cases, there are ways to limit squirrel damage without the need for extermination or removal.

The Pacific Northwest

Are Western Grays Endangered?

In Washington, the Western Gray Squirrel is listed as a threatened species. A 2007 estimate put the statewide population between 468 and 1,405 individuals, based on data from 1994–2005. Estimated net habitat loss from 1993 to 2017 was 20.8% in the North Cascades and 21.2% in the South Cascades due to wildfires and timber harvest (Vander Haegen et al., 2022).

In Oregon, Western Grays are listed as a sensitive species in key oak-woodland regions. Eastern Gray and Fox squirrels were introduced in the late 1800s and early 1900s in both states and pose similar challenges to natives.

References


What We Do

Tree Squirrels of California is dedicated to providing accurate information about the tree squirrels of the West Coast and how to distinguish them from other types of rodents in the squirrel family, Sciuridae.

It's important to remember that squirrels are wild animals and your interactions with them are guided by state and local laws. T.S.O.C is here to keep you up to date on these laws and also to dispel common misconceptions about these enthusiastic rodents so that we can better coexist.

Western Gray Squirrels may be shy of humans and seem docile, but they are fierce and highly territorial around non-native species of squirrels.
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