A simple plan, which is usually successful in finding out if a Woodpecker is at home in its nesting hole, is to strike a few sharp blows on the tree with some convenient club or rock. After a little treatment of this kind the bird will often come to the entrance and look down, as if to inquire into the meaning of all the disturbance. If the nest has been newly made many fragments of small chips of wood will be found on the ground beneath the tree.
_Variety of Situations._--The student who takes up { 37} the subject of nest architecture will soon be impressed not only with the wide assortment of materials used, but also with the wonderful variety of situations chosen.
[Illustration: The Grebe or "Water Witch"]
The Grebe, or "Water Witch," builds one of the most remarkable nests of any American bird. It is a floating raft, the buoyant part of which is the green { 38} stems of water plants, not bent over, but severed from their roots and piled across one another. On this platform is collected decaying vegetation gathered from beneath the water. Here the eggs are deposited, and are carefully covered with more decaying vegetation when the bird desires to be absent from the nest.
_Variation in Families._--Sometimes there is wide variety in the character of the nests of different species classified as belonging to the same family. The Flycatcher group is a good example of this fact. Here we have as one member of the family the Kingbird, that makes a heavy bulky nest often on one of the upper, outermost limbs of an apple tree. The Wood Pewee's nest is a frail, shallow excuse for a nest, resting securely on a horizontal limb of some well-grown tree. Then there is the Phoebe, that plasters its cup-shaped mass of nesting material with mud, thus securing it to a rafter or other projection beneath a bridge, outbuilding, or porch roof. Still farther away from the typical Flycatcher's { 39} nest is that made by a perfectly regular member of the family, the Great-crested Flycatcher. The straw and other substances it collects as a bed for its eggs and young is carried into some hollow tree, old Woodpecker hole, or nesting box. Often a cast-off skin of a snake is used, and sometimes the end is permitted to hang out of the hole--a sort of "scare-crow," perhaps, intended for the notice of annoying neighbours.