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Monday, July 28, 2014

A new mammal for Bodega Head?

Two days ago while at work, I caught a glimpse of a small gray animal gliding over the ground, and I thought to myself, "Huh?"  From that brief view, I would have guessed that it was a ground squirrel, but as far I knew, there were no records of ground squirrels from Bodega Head.  The animal disappeared among some pipes.

I alerted Emily because I knew she walked in that area frequently.  Today she told me that she spotted the animal just before noon (Thanks, Emily!).  I went back to the area and at first was disappointed not to find it.  Then I was drawn to some Barn Swallow scolding and looked closely to see the animal slightly hidden by vegetation.

Once it came out into the open, I got a few decent pictures for the record:



You can see the dappled fur pattern in the next two pictures:



I don't have a lot of experience identifying ground squirrels, but I think this is a California Ground Squirrel (now called Otospermophilus beecheyi).  As far as I know, this is the first time a ground squirrel has been recorded on Bodega Head (but please correct me if I'm wrong).

I've started asking around about the distribution of ground squirrels in Sonoma County.  It sounds like they're rare on the coast.  The Natural History of Ground Squirrels in California by Grinnell and Dixon (1918) says, 

"To the westward they extend within a mile of the seacoast in the vicinity of Eureka and at Cape Mendocino, but elsewhere mostly not closer to the sea than eight or ten miles. Nowhere in the immediate coast belt are they reported especially numerous or injurious."

Here's a map showing ground squirrel distributions from that publication.  Look at the records for "Douglas Ground Squirrel", which is now a subspecies of California Ground Squirrel, in the northwest corner of the state (the open triangle symbols):


Note how few records there are from the Sonoma/Marin coastal areas (in fact, a complete gap is shown in southern Marin County).  The one triangle represented in western Sonoma County is mentioned in the text as "7 miles west of Cazadero."  I plotted that location, and it brings you pretty close to the intersection of Meyers Grade Road and Fort Ross Road (and that's about 3 miles from the coast).

I'd love to hear more about records of ground squirrels in Sonoma and Marin counties, especially near the coast.  I'm sure more records have been added to the map since 1918.  Write to me if you've seen them!

3 comments:

Claudia said...

Apparently we have Spermophilus beecheyi at the Fairfield Osborn Preserve (I had to double check the species list because I don't recall seeing them very often.)

Seems like it's time for a SPECIES LIST PARTY EXTRAVAGANZA!! Don't you love it when species lists actually can be used to answer questions?

RandomEcologyDude said...

Hi Jackie,

did you spot any burrows? or any network of burrows? These guys are pretty social down here in southern california, so hopefully you'll see more!

Jackie Sones said...

I might have seen some signs of burrowing, but I'll have to keep looking to see if the squirrel actually goes underground there. This animal has a small, but perhaps distinctive hole in its left ear (see photos), so it might be identifiable if there is a question about whether there are multiple individuals or not...or whether it wanders to other locations.