Back near the beehive an hour and a half later. Something had been busy boring into this dead tree. (One of several such trees I'd seen)

Update from the Sierra Naturalist yahoo group:

Here is what my husband (a guy with an advanced degree in forest
ecology) had to say about the picture of the bored tree.

"It is a classic picture of feeding by a pileated woodpecker.
Pileated woodpeckers are the largest western woodpecker and had been
assumed to be the largest remaining woodpecker in the USA until the
Ivory billed were rediscovered.
Given the snag it was going into, it was probably after carpenter
ants. Pileated will also feed on downed logs. We have them on our
property in Oregon and have seen similar feeding close to the ground
on Douglas fir snags. One dead giveaway for a pileated woodpecker is
the size and shape of the hole. Pileated almost always have
rectangular shaped holes, large in size. The nesting entry hole is
the largest around but flicker's will also have fairly large holes but
they are more or less circular."