Friday, December 21, 2012

A Stirring Creature

'Twas the night before Christmas, when all thro' the house
Not a creature was stirring, not even a mouse...

Perhaps very soon, but...

Just after Thanksgiving, when it twasn't yet
There was a stirring near a cam I'd set
Seems the seeds I'd sprinkled had attracted a mouse
But in manzanita near Mariposa, and not in the house.

brush mouse

brush mouse

brush mouse

brush mouse

That longer than body-length bi-color tail, tufted tip, big ears and eyes, and brown-gray fur and white belly ID this character as Boyle's Deer Mouse, Peromyscus boylii, aka a Brush Mouse. At least in my humble IDing opinion (IMHIO). Brushies are climbers that forage up in shrubs and trees, and are well-known to live in manzanita groves, so the habitat fits too.

Have to say - I love the dark gray on the face and legs. Reminds me of our dusky-footed woodrats, Neotoma fuscipes, for which deer mice are the nearest living non-Neotoma relative.

brush mouse

brush mouse

brush mouse

brush mouse

Btw - there's a ton of confusing info out there on Peromyscus boylii and Peromyscus truei, the Pinyon Mouse. Both on the web and in respected books. For example, multiple references, such as the Smithsonian website and Animal Diversity Web, suggest that boylii is only found above 2,000 meters. That's not correct - they've been studied extensively in the Sierra Foothills and California Coastal Ranges below 3,000 feet - aka under 1,000 meters. Perhaps these websites are meant to read "below 2,000 meters," and it's just a typo.

Also, the indispensable Jameson and Peeters, Mammals of California, shows truei in the Santa Cruz Mountains and not boylii. Well, it's the other way around. From what I can tell, no truei has been found, and boylii has been well documented and studied.

So, whether you're scurrying around the Intertubes, or flipping notable pages - be cautious as a mouse with those references. Knowledge changes.

Happy Christmas to all, and to all a good night.



  1. He is right where he much more to appreciate about a mouse when he is out and about and not in one's house.

    I appreciate your thorough going caution as you study and is a good example that could be emulated by many undisciplined in their disciplines.

  2. Holy crap those are some cute ears!

    1. Yes, their audaciously cute ears are only rivaled by those of the pinyon mouse. I've read smatterings here and there that they sometimes use them to echo-locate by squeaking and listening for the bounce backs. Must look into that more...

  3. look at those ears. P. boylii and trueii are so hard to tell apart. I need to pick your brain some more the next time we are together in front of a computer.


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