Squirrel drinking from my bird bath

Angel went racing out the doggy door barking.  I guessed that either the hawk or the squirrel dared to enter the yard to drink out of the bird bath.

Only a few minutes later, while Angel was laying in the grass facing the other direction, the squirrel came back.

 Checking to see if Angel notices:

Is the dog watching?

Drinking:

Good,non-chlorinated water

The squirrel watched, then drank multiple times in only a couple minutes.  

Then - on alert:

Something moved.

Making its escape:

Jump to the top of the wall

Get safely to the top of the wall:

Made it.

Flee:

Heading home

I'm not sure what startled it.  Maybe me taking pictures.  Neither Angel or Bogie realized it was there.  

It lives in a hole on the undeveloped side of the wall, under a big mesquite tree.