Breaking and Entering: Squirrel Moves into Opossum Den

We have another new sighting for the North Campus. A California ground squirrel has been spotted using the opossum den located underneath one of our Museum sheds. So far it seems that both the opossums and the squirrels are sharing the space!

Sam Easterson's camera trap captures the first image!

This is what Jim Dines, our Mammalogy Collections Manager, has to say about them:

The California ground squirrel, as its name suggests, is common throughout California as well as the rest of the western U.S. Scientists know this rodent as Otospermophilus beecheyi (formerly known as Spermophilus beecheyi). They are diurnal (active during the daylight) and, like other ground squirrels, live in burrows that they excavate or take over from other animals. Our ground squirrel has apparently moved into a den built by an opossum.

Ground squirrels eat seeds, nuts, and a variety of other plant material, as well as insects and handouts left by humans. Since they also invade gardens and cultivated areas, California ground squirrels are commonly regarded as pests. Their extensive burrow systems can be very destructive. They are also a host to fleas that can carry plague, so pose a health risk to humans and their pets. Rattlesnakes are one of the main natural predators of California ground squirrels and the squirrels have developed an interesting defense mechanism: the ground squirrels will eat the shed skins of rattlesnakes and then lick themselves and their young, thus covering themselves with rattlesnake scent and confusing a potential rattlesnake predator into thinking it is merely smelling another rattlesnake. Pretty sneaky, eh?

The California ground squirrel has a fairly bushy tail so is sometimes mistaken for the Eastern fox squirrel (a tree squirrel), but has different colored fur and retreats underground instead of up into a tree.

Watch Sam accidentally startle the squirrel into the den!

Squirrel Stew

What's For Dinner (and the Unintended Consequences of Every Introduction)?

The Eastern fox squirrel, Sciurus niger, was imported to Southern California in 1904 by veterans of the Civil War and Spanish American War, at the time living at the Veterans Home in West Los Angeles.  The war veterans mostly came from the southern US (e.g., Tennessee, Kentucky) and kept as caged pets tree squirrel native to their home states. Perhaps it is apocryphal, but I've heard that the squirrels weren't just pets, they were also used in that old-time favorite—squirrel stew!

Whatever the reason for keeping the squirrels, eventually an overzealous hospital administrator noticed that they were being fed table scraps and, deeming this illicit provisioning a misuse of government support, turned the squirrels loose.  The fox squirrels did quite well in their new habitat and it wasn’t long before they spread throughout the region.

Today we find Eastern fox squirrels from Oxnard to Ontario and from Santa Clarita to south Orange County.  As their range has expanded, the fox squirrel has increasingly come into contact with the Western gray squirrel, the native tree squirrel that lives in the foothills and mountains of Los Angeles.  Biologists are very interested in studying the ecological effects of these two species as they come into contact, including possible displacement or hybridization.


Here in Exposition Park we have a large and feisty population of these squirrels. At lunchtime they can often be seen wrestling French fries and sandwiches out of field trippers' hands. Here's some footage Sam Easterson captured of one of them eating lunch crumbs off the sidewalk.

In addition to this footage Sam is trying to capture some non-traditional footage for our new Nature Lab exhibit. We're hoping to show you nature like you've never seen it before, and Sam thinks this peanut cam might help! He says, "I like the idea of the squirrel shooting footage. Maybe he/she will take the peanut up a tree or even bury it underground." Whatever happens, I'll be sure to keep you all in the loop as we try out the peanut cam.

Sam's prototype peanut cam!

Thanks Jim Dines, Mammalogy Collections Manager, for all the Eastern fox squirrel facts! 

Black Phoebes Build Nest

More Nest Surveillance

This week we found another active bird nest! This nest belongs to a pair of Black Phoebes, Sayornis nigricans, and is built under the eaves of the Rose Garden maintenance shed. Once again this find is thanks to Kimball Garrett, who noticed the nest Monday morning on one of his regular Expo Park bird surveys. 

 Footage of the phoebe landing on her nest

Naughty Neighbors

This is the second nest Kimball has found in this location this year, but it is a site that has been used by phoebes in past years. Unfortunately, this year's first nest was disturbed by unknown causes, but it is possible that a squirrel is to blame. Eastern Fox Squirrels, Sciurus niger, are very common in Expo Park, and they are known nest predators. When they locate a nest they will eat any eggs or young birds they find. We'll never know for sure if a squirrel is to blame for the first nests' failure, but fortunately the phoebes persevered and built a second nest.

Eastern Fox Squirrel on top of the Butterfly Pavilion

Better Luck This Time

Until today we were not sure if the new nest contained any eggs. This morning Kimball and I went out with a mirror and now we can confirm there are four eggs!

Kimball checks out the nest

The mirror reveals four eggs in the clutch

Now that we know there are eggs, we are going to regularly monitor the nest. I'll keep you posted as the eggs are incubated, they hatch and then the immature birds develop. If we are lucky, we'll be able to document the entire process.