Flickers, or "Yellowhammers," use dead trees as a rule, but sometimes make use of a living tree by digging the nest out of the dead wood where a knot hole offers a convenient opening. The only place I have ever known them regularly to nest in living trees is in the deserts of Arizona, where the _saguaro_ or "tree cactus" is about the only tree large enough to be employed for such a purpose. In the {35} Northern States Flickers sometimes chisel holes through the weatherboarding of ice-houses and make cavities for their eggs in the tightly packed sawdust within. They have been known also to lay their eggs in nesting boxes put up for their accommodation. In travelling through the pine barrens of the Southern States one frequently finds grouped about the negroes' cabins and plantation houses the popular chinaberry, or Pride of India tree. Here are the places to look for the nest of the Hairy Woodpecker. In that country, in fact, I have never found a nest of this bird except in the dead, slanting limb of a chinaberry tree. The member of this family which displays most originality in its nest building is the Red-cockaded Woodpecker. It is a Southern bird, and the abode for its young is always chiselled from a living pitch-pine tree. This, in itself, is very unusual for any of our eastern Woodpeckers. The bird, however, has a still stranger habit. For two or three feet above the {36} entrance hole, and for five or six feet below it, all around the tree, innumerable small openings are dug through to the inner bark. From these little wells pour streams of soft resin that completely cover the bark and give the trunk a white, glistening appearance, which is visible sometimes for a quarter of a mile. Just why they do this has never been explained. It is true, however, that the sticky resin prevents ants and flying squirrels from reaching the nest, and both of these are known to be troublesome to eggs and young birds. 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"]