He has a sweet song, but it is so low you have to be very near and very quiet to hear it. He is such a talkative, restless fellow, however, that you often see him when you might not hear the song. The gnatcatcher is one of the most lively of birds. He bustles about in an eager way that shows everybody where to look for the nest. And when there is no nest, he flits over the tree-tops, catching tiny flying insects, and uttering a queer call that sounds something like the mew of a cat. He does not need to be so quiet as birds who build on the ground or near it, because few can get at the nest. It is too high for snakes and boys, and on branches too light for squirrels or big birds. So he can afford to be as chatty as he pleases. The nest of this bird is one of the prettiest that is made. It is a little cup, upright on a branch, usually near the end so that it is tossed by the wind. Miss Merriam found a pair of gnatcatchers in California, and watched them through many troubles. Their way of building was by felting. That is, they took fine, soft materials like plant down, and packed it all closely together by poking with the beak and prodding it with the feet. A gnatcatcher's nest is large for the size of the bird. It must be deep for safety, so that eggs and nestlings will not be thrown out by the wind. Three times, Miss Merriam thinks, the little family she watched had to build their nest. Each time it took more than ten days of hard work. This pretty little fellow has a long tail, and he keeps it in motion all the time. He jerks it up or down, or twitches it to one side or the other; or he flirts it open and shut like a fan, which shows the white edges and looks very gay. Dogs and cats, as you know, show how they feel by the way they move the tail. Birds do the same, some much more than others. If you watch the way in which they move their tails, you can learn to tell how a bird feels almost as well as if he could speak to you. FOOTNOTE: [3] See Appendix, 2. IV THE NUTHATCH AND CHICKADEE FAMILY (_Paridæ_)[4] THIS is another family of small birds. The nuthatches are lively, restless little creatures. You generally see them scrambling over the trunks of trees, head up or head down, as it happens. They are dressed in sober colors, and spend their lives picking tiny insects out of the crevices of the bark. The WHITE-BREASTED NUTHATCH is the best known in the East. In California the slender-billed takes his place, being about the same in dress and manners. Both of them, East and West, go about calling "quank, quank." The dress is slate-blue and white, with a white breast, a black cap, and black on wings and tail. Nuthatches nest in holes, either deserted woodpecker nests or natural holes in trees. If such a place is not to be found, the pair will sometimes dig out a home in a decayed stump for themselves.