SoCal's native gray squirrel, left, and the Eastern fox squirrel.
The contest for dominance between LA's two main squirrel species has been one of my favorite local wildlife situations since I first encountered it researching the roots of the Veterans Affairs campus in West LA. It's a compelling tale because we see it playing out right in front of us, and because of the backstory. Basically, the Western gray squirrel is native to Southern California and mostly eats (and spreads, crucially) tree nuts. The Eastern fox squirrel, the more greenish or reddish animal seen above, was brought to the Los Angeles area at the start of the 20th Century in the belongings of residents at the National Soldiers Home, precursor to the VA property. The Easties eat everything. They also reproduce and expand their range aggressively, and have pushed out the grays to become the most common squirrel in much of Los Angeles. I can't remember the last time I saw a real gray squirrel.
This all came to light through research at Cal State LA over the years, and a current project is studying some of the gray squirrels that have hung on in Griffith Park. From Brenda Rees at the SoCal Wild website:
As a biological sciences professor at Cal State LA, Muchlinski took on the task of discovering how this non-native species was affecting SoCal’s resident Western gray, a critter that hasn’t been under the microscope much. It’s a squirrel, after all, a taken-for-granted species that doesn’t have the powerful draw of a mountain lion or big-horned sheep.
“So many people would say, ‘What’s the big deal? One species replacing another? What does it matter?’ But the reality is introduced species cause problems with the natives and affect the ecosystem,” he says. “We just don’t know what the complete consequences are.”
Comparing gray maternal genetic profiles in Griffith Park, DeMarco is discovering disturbing trends – basically, gray squirrels’ genetic makeup is similar because they are inbreeding. Even though squirrels are known for their acrobatics and wire walking abilities, the grays find it difficult to branch out beyond their original homes. Traffic and human development keep them stuck. Besides isolation, grays are up against other factors: poisons, roadkill, destructive fires and competition with the Easties.
“Studies have shown it’s possible for grays and Eastern fox squirrels to coexist,” says DeMarco explaining that in areas with a wide diversity of tree species – like Ferndell – there is a higher proportion of Western grays. “There could be a way to sustain these two species if there were more pine, walnuts and sycamore trees in the area, trees the grays like. Here in Ferndell, grays and Eastern fox squirrels seem to coexist for the most part.”