Bounding

 

A nice set of tracks in the Bodega Dunes.  Each footprint was very small — I didn't measure at the time, but I'd estimate less than 1 cm long. 

Note that the prints occur in sets of four with gaps in between (follow them diagonally from the lower left corner to the upper right corner of the picture).  This pattern indicates that the animal was bounding across the sand, rather than walking.

Here's a closer view of two sets of tracks (below).  Although subtle, you should be able to see that in each set, two prints are slightly smaller than the other two.  Which ones are smaller — the two in front that are side-by-side, or the two in back that are one-in-front-of-the-other (a bit offset)?

 

It's the two in back that are one-in-front-of-the-other that are smaller — and these are the front feet.  When bounding, the animal planted its front feet first, and then placed its hind feet ahead of the front feet.

The individual toes are visible in the picture below (there should be five toes, but they don't always register in the sand).

 

You can probably tell that this is a small mammal.  I'm guessing it's either a mouse or a vole.  I haven't learned to tell their tracks apart yet, but based on the bounding behavior, I'm leaning towards mouse (Peromyscus sp.).  What do you think?

A small visitor

When reaching for some seed to feed the birds at a friend's house in Salmon Creek, I noticed a small visitor in the bottom of the storage container.

 

Here's a close-up.

 

I think it's a Deer Mouse (Peromyscus maniculatus) — but correct me if I'm wrong!

I was curious about their noticeably long whiskers, or vibrissae, and how they might be used.  Unfortunately, I couldn't find much information about mouse vibrissae.  

So instead I searched for information about feeding in Deer Mice (How much bird seed had the mouse eaten?  Or in this case, perhaps it should be called "mammal seed" rather than bird seed?).

It turns out that a study was published about the effects of extra food on small rodent populations such as Deer Mice (Taitt 1981).  When given supplemental food, the mice decreased the sizes of their home ranges.  They were also able to reproduce even in poor weather conditions (e.g., the extra food allowed them to override the effects of cold temperatures that normally would have delayed breeding).  The author of this study suggested that Deer Mouse populations may be limited by seasonal food availability. 

This was just one mouse and a brief adventure in a bird seed container.  I don't think it will change the Deer Mouse population in Salmon Creek, but it probably made for a satisfied mouse!

 

Crossroads

Open sand in the dunes is wonderful for revealing animal tracks.

Here two animals crossed paths — a small mammal with sets of four small circular depressions (probably a mouse) and a bird (probably California Quail).  Did the mouse pass by at night, and the quail during the day?

And here's a typical rabbit track — the two larger hind feet are in front placed side-by-side (upper left), and the two smaller front feet are in back, one in front of the other (lower right).