Then, too, it is dark in the cavity of the nest, consequently the skin could not serve as a scarecrow in any case. Hence, whatever its purpose may be, it surely is not that. It looks like a mere fancy or whim of the bird. There is that in its voice and ways that suggests something a little uncanny. Its call is more like the call of the toad than that of a bird. If the toad did not always swallow its own cast-off skin, the bird would probably use that too. At the best we can only guess at the motives of the birds and beasts. As I have elsewhere said, they nearly all have reference in some way to the self-preservation of these creatures. But how the bits of an old snake-skin in a bird's nest can contribute specially to this end, I cannot see. Nature is not always consistent; she does not always choose the best means to a given end. For instance, all the wrens except our house wren seem to use about the best material at hand for their nests. What can be more unsuitable, untractable, for a nest in a hole or cavity than the twigs the house wren uses? Dry grasses or bits of soft bark would bend and adapt themselves easily to the exigencies of the case; but stiff, unyielding twigs! What a contrast to the suitableness of the material the hummingbird uses--the down of some plant, which seems to have a poetic fitness! Yesterday in my walk I saw where a red squirrel had stripped the soft outer bark off a group of red cedars to build its winter's nest with. This also seemed fit,--fit that such a creature of the trees should not go to the ground for its nest-material, and should choose something soft and pliable. Among the birches, it probably gathers the fine curling shreds of the birch bark. Beside my path in the woods a downy woodpecker, late one fall, drilled a hole in the top of a small dead black birch for his winter quarters. My attention was first called to his doings by the white chips upon the ground. Every day as I passed I would rap upon his tree, and if he was in he would appear at his door and ask plainly enough what I wanted now. One day when I rapped, something else appeared at the door--I could not make out what. I continued my rapping, when out came two flying-squirrels. On the tree being given a vigorous shake, it broke off at the hole, and the squirrels went sliding down the air to the foot of a hemlock, up which they disappeared. They had dispossessed Downy of his house, had carried in some grass and leaves for a nest, and were as snug as a bug in a rug. Downy drilled another cell in a dead oak farther up the hill, and, I hope, passed the winter there unmolested. Such incidents, comic or tragic, as they chance to strike us, are happening all about us, if we have eyes to see them.