March 2007, west of Tercero Squirrels may be the second most populous large animal after ducks in the arboretum. (In fact, if you count ground squirrels and arboreal squirrels in the same category, there are probably a lot more squirrels.) 

The word squirrel is actually quite poetic. It derives from an ancient Greek word meaning "shadow tailed."

July 4th, 2013, was hot.


Tree Squirrels

The most visible rodent species in Davis is the non-native Eastern fox squirrel (Sciurus niger), which makes its home in trees all around Davis. The second most visible rodent species is its close cousin, the non-native Eastern gray squirrel (Sciurus carolinensis). Both are tree squirrel species, both were introduced to California from the Eastern United States in the early 20th century, and both have been increasing their populations in California ever since.

While most (if not all) of the tree squirrels in Davis are brown, some areas (notably Marysville, KS and Washington DC) have significant populations of black fox squirrels (they are the same species, just a different color). There are also populations of black-colored Eastern gray squirrels in the Eastern United States.

Fox squirrels are extremely numerous on the UCD campus, spawning the Fox Squirrel Contraceptive Research Project. The project has two key objectives: to reduce the campus fox squirrel population before they cause problems, and to test a new birth-control drug that wildlife biologists hope will help them manage other mammals that are pests in some places, such as deer and ground squirrels. The goal "is to limit their ecological and human-health impacts as effectively and humanely as possible." This article has further details.

Invasive tree squirrels were not a problem in Davis until the 1990s. First reports of damage in gardens came in from southeast Davis and El Macero. Within a couple of years tree squirrels were throughout South Davis, then East Davis. By the mid-2000's tree squirrels were in Central and North Davis, and now damage reports come from all parts of town. One of the biggest problems with them is their propensity to enter the attics of human residences. However, they can be warded off by setting up LED strobe lights, which irritate the squirrels enough to make them leave. Adequately sealing all entrances to the attic will also keep them out.

There is also a native tree squirrel species in Yolo County, the Western gray squirrel (Sciurus griseus). However, the native Western gray squirrel cannot survive in most residential neighborhoods. It requires a continuous stretch of tall oak trees for habitat, both because its diet consists predominantly of acorns and truffles (which grow on tree roots), and also because it is very averse to climbing down out of the trees for long enough to access an isolated tree. Its populations have been shrinking for many decades due to the loss of oak woodland habitat. Per the California Department of Fish and Game range maps, Western gray squirrels in Yolo County live only in the foothill areas plus in the low-elevation Dunnigan Hills and along the Sacramento River.

Ground Squirrels

The only ground squirrel species in Yolo County is the native California ground squirrel (Otospermophilus beecheyi). It is found in all parts of Yolo County.

Both ground squirrels and tree squirrels can damage plants and crops. Ground squirrels are a problem on farms, whereas tree squirrels harm garden and landscape plants in town.

Also, tree squirrels are a protected game species, so they can only be killed during squirrel hunting season. They are considered edible. Ground squirrels are not protected. They don't taste good. Management guidelines here.


Chipmunks are also members of the squirrel family. The only chipmunk found in Yolo County is the native Sonoma chipmunk (Neotamias sonomae). It lives in the foothills along the western edge of Yolo County.

Tree Squirrel Identification

(Sciurus niger aka Eastern Fox Squirrel, Introduced species from the Eastern United States)

Eastern fox squirrels typically have a lot of very bright, red or orangey-brown fur, especially on their faces. They have cream colored undersides.

Eastern fox squirrel Eastern fox squirrel Stop looking at me!  A snack in the trees.  Hello!

(Sciurus carolinensis aka Eastern gray squirrel, Introduced species from the Eastern United States)

Eastern gray squirrels are about 25% smaller than both Eastern fox squirrels and Western gray squirrels. They also tend to have shorter fur, and their tails are less bushy. Their fur is mostly a mottled gray-brown color, and they have cream colored undersides. They typically have some brownish color on their faces, but it's a duller brown and covers a smaller area of their faces than the brown on the faces of Eastern fox squirrels.

Eastern gray squirrel by queerbychoiceEastern gray squirrel by queerbychoiceJ Street Davis Squirrel by Constantia Oomen A squirrel in the quad.



(Scuirus griseus aka Western Gray Squirrel, Native to the Western United States)

Western gray squirrels are a cool, silvery shade of solid (unmottled) gray, with white undersides. They do not have any brown on their faces.

Western Gray Squirrel (inhabiting Lake Solano Park).

Ground Squirrel Identification

(Otospermophilus beecheyi aka California Ground Squirrel)

A squirrel peeking from bushes in the arboretum. They seem to do that a lot. yeah this is what they do most of the time One last peek before he ducks into his hole.

Hiding under a bush in the Arboretum. Ground squirrels are responsible for holes in the ground all over the Arboretum.


see also: Squirrel Fishing


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2005-03-02 12:37:19   They're so cute. Too bad they're savage, rabies-infected beasts. —SummerSong

According to an AP article on USA Today's website, "Rabid squirrels are extremely rare, with only eight reported cases since 1950."

2005-08-15 11:44:21   In the Philadelphia Suburbs, they're often referred to as "Goddamned Bird Feeder Tree Rats." —BlancheNonken

2005-11-27 20:51:52   I love all the frickin squirrels in Davis. They're spastic and vicious. :) —AubreyJohnson

2006-02-17 21:19:16   As my sister says, "rats with bushy tails" —MatthewTom

2006-02-17 21:49:21   Fact: baby squirrels are called kittens —KrisFricke

  • AFAIK, like most (all?) rodents, they are called pups, with the males being kits and the females being kittens. All the rodent breeders, associations and vets I've run into generally just call them pups (I think since sexing is difficult at an early age). Squirrels might be an exception, but I've always heard it was for all rodents.JabberWokky, peromyscus and fancy mice fan.

2007-03-24 22:57:47   10 years ago there were no tree squirrels on campus. Maybe they were in other parts of Davis (I don't think so) but certainly not on campus. Where did they come from? —JimEvans

Rumor or guess is the hitched a ride from Sacramento where they have a well established urban population.The expert to ask is professor Doug Kelt of WFCB. —AlexMandel

    2007-05-12 21:32:38   Someone could have brought some squirrels onto campus in hopes of starting a population on campus. Some people did that with Black Squirrels at Kent State. Pretty soon Black Squirrels took over and became the unofficial mascots of the school. (There are some black ones in Palo Alto)—Jedron

    2007-05-16 13:24:22   The other day I saw two bluebirds fighting a squirrel. The birds were jumping around on the ground and then swooping up and attacking the squirrel and the squirrel swatting at them. Also, I once saw a squirrel beatboxing around 5 or 6 in the morning. It was frightening. —BrianTrott

    • Probably a Scrub Jay rather than a bluebird. —JimEvans

    2007-05-16 13:29:36   One more story involving Davis squirrels. A couple weeks ago I was biking and I biked passed a dead squirrel with a crow pecking at it. Then the crow flew away and the squirrel was runover by an SUV. This bothered me, because it was my birthday and I think that has to be some sort of bad omen. —BrianTrott

    2007-05-17 08:59:50   I think its cool when the squirrels on campus at the MU run around the trees at high rates of speed. Do you think they get dizzy?... —MyaBrn

    2007-05-17 19:29:15   It's nice to see a resurgence in the squirril population, cats had then pretty much under control for quite some time —StevenDaubert

    Hmm, I'm not so sure about this, when I moved to davis in '99 there were no tree squirrels to be found in most of the city, since then the Eastern Fox squirrels have expanded rapidly taking over much of campus but you'll notice not to far into the rest of town yet. I doubt house cats had much to do with this. —AlexMandel

      • I've now seen tree squirrels in the Stonegate area (far west Davis). So, the spreading of tree squirrels appears to be continuing.

    The brown tree squirrells are certainly exploding population wise in the last 2 years, they were just a trace species on campus for 40 years. I wonder if the removal of the owl boxes was part of why the population has very very rapidly exploded

      2008-04-09 17:14:28   Has anyone seen the wierd squirrel with that crazy eye problem? What is up with that?!? Freaky! —emargie

      2008-10-14 14:14:05   So what do we do now? Should we start an erradication program? —rgrasso

      2008-10-14 19:57:00   Davis squirrels are so cute! I always wondered if the ground squirrel was a squirrel, I was calling them squirrelmunks, across between a chipmunk and a squirrel.

      There is a red mouthed squirrel who lives in my walnut tree, that little jerk is always peeling walnuts over my doorstep and dropping them on the roof. He also barks at me and my cats on weekends, very rude. Is a barking vicious squirrel exhibiting symptoms of rabies, or is this normal behavior? Squirrel fights can also be quite loud, downright ferocious. —CarrieBishop

      2008-10-15 01:18:44   No worries about rabies from squirrels. The raspy "barking" is normal behavior. They do it when startled or feeling threatened. According to the U.S. government CDC site: Small rodents (e.g., squirrels, hamsters, guinea pigs, gerbils, chipmunks, rats, and mice) and lagomorphs (including rabbits and hares) are almost never found to be infected with rabies and have not been known to transmit rabies to humans.

      2008-10-15 07:22:07   Squirrels in California are carriers of bubonic plague on the other hand. —NickSchmalenberger

      • Which is very treatable with easy and full recovery with modern medicine (assuming you go to a doctor). —jw

      2008-10-15 15:24:58   Yes, rodents can carry the bacteria Yersinia pestis, which is also known as bubonic plague, but it is the fleas that bite the rodents, and then bite a human that transmits it. So, you aren't going to get it by being attacked by a vicious squirrel. You would have to be bitten by fleas that had bitten an infected rodent.

      According to our govt's CDC website: Q. Who is at risk for getting plague? A. Outbreaks in people occur in areas where housing and sanitation conditions are poor. These outbreaks can occur in rural communities or in cities. They are usually associated with infected rats and rat fleas that live in the home.

      Our area in Northern California is listed as reporting 1 case from 1970-1997.

      2008-10-15 20:52:08   these guys have taken over the town over the past 5 years. its rediculous. —ChrisWaterstraat

      2008-10-15 20:54:06   I <3 squirrels. :)


        2008-10-21 19:10:00   I say we take the town back, who's with me! —rgrasso

        2008-11-03 10:49:12   Hormones for those little invaders. Killing them would be much more effective.

        2009-04-02 22:33:13   someone please explain .. I swear I saw a squirrel near Mrak Hall the other day with the number 14 on its rump in black. Is there some kind of survey or experiment going on or have I just been watching wayyyyy too much Lost? Some of the other ones on campus seems to have weird black burn or paint marks on their rear ends, but I haven't seen any other numbers. Maybe I was hallucinating .... —LaFrance

        2009-08-18 13:12:13   Tree rats, not to be confused with pigeons which are winged rats. Philadelphia suburbs have every possible variant of rats. —AndrewSaint

        2010-06-09 20:56:10   Yes, the squirrels around Mrak Hall are part of the Fox Squirrel Contraceptive research project (why's there no page for this?). They're marked with dyes for identification. —skurniaw

        2010-09-30 15:11:25   The squirrels have eaten one of the pumpkins I put by the front door! Rotten things - these were grown by my mother-in-law for my young son. Is there any way to deter the critters from destroying the other pumpkin? Painting it with toxic chemicals? —NoelBruening

        • Try spraying it with Hot Pepper Wax spray. You should be able to find it at Davis Ace Hardware. —DonShor

          Does Redwood Barn Nursery not carry it, or are you just being modest/avoiding promoting on the wiki? —TomGarberson

          • We don't actually carry it; our wholesale distributors don't stock it. But thanks for the plug! —Don

          2010-09-30 18:57:41   Squirrels are just rats with bigger tails. Here in Upstate NY, at my old place the squirrels used to throw acorns at my wife and our dogs as she walked them —PeterBoulay

          2010-12-27 19:33:26   I think I saw a squirrel with a shaved tail on campus. I saw it near Hart Hall and Wellman, and it looked terrified. I was wondering if their was some rat-tailed breed or something, but I really think someone just caught the poor thing and shaved its tail. How sad. —Michellaneous

          • They lose them as a defense mechanism when evading predators. Well, the loss isn't the defense mechanism... it's the fact that it looks like there's a big fuzzy body to grab, but all the hunter gets is a bunch of fur and a squirrel gets away (minus their tail). They also shed them annually, however I believe local squirrels would only lose their tail during the spring molt (they generally don't lose their tail during the fall shedding). There are also a whole slew of parasites that cause hair loss, and — while I can't speak for squirrels in specific — many other types of rodents chew off each other's hair as a type of dominance (in the types of rodents I'm more familiar with, it's called "barbering"). It's also possible you saw a different local rodent that you mistook for a squirrel. If it looked terrified, it might be because it was flushed out into the open. Other than squirrels, most local rodents really don't like being in the open, and tend to limit their time outside of cover. ⁓ʝ⍵