Even Skookum noticed it.

But it was not repeated.

Next morning they went on.
There are many quaint sounds in the woods at all times, the rasping of trees, at least a dozen different calls by jays, twice as many by ravens, and occasional notes from chicadees, grouse, and owls.

The quadrupeds in general are more silent, but the red squirrel is ever about and noisy, as well as busy.
Far-reaching sounds are these echoes of the woods--some of them very far.

Probably there were not five minutes of the day or night when some weird, woodland chatter, scrape, crack, screech, or whistle did not reach the keen ears of that ever-alert dog.