The white streak over the Mountain Chickadee's eye, where the Master Workman's brush slipped, has not masked its relationship even to the observer who sees the bird for the first time. It is a Chickadee—there's no mistaking that fact. They are just as full of vim—just as inquisitively, unsuspiciously friendly as the bird calling “phee-be" from the old apple tree outside the window this clear July morning. They add another “de", though, and sometimes reverse the notes or vary the call by placing the long “phee" in the middle between two “de's."
Dr. Merrill states that the female sits tight and when disturbed keeps up a constant hissing so much like that of some snakes that no prudent squirrel would venture to enter the hole.
The nest is in a natural cavity or deserted woodpecker hole, usually lined with rabbit fur.