Having received eager encouragement, he resumed: "My favorites, the bluebirds, we have considered quite at length. They are very useful, for their food in summer consists chiefly of the smaller beetles and the larvae of little butterflies and moths. Many robins stay all winter. It is a question of food, not climate, with them. In certain valleys of the White Mountains there is an abundance of berries, and flocks of robins feed on them all winter, although the cold reaches the freezing-point of mercury. As we have said, they are among the most useful of the insect destroyers. The golden-crested kinglet is a little mite of a bird, not four inches long, with a central patch of orange-red on his crown. He breeds in the far North, and wintering here is for him like going to the South. In summer he is a flycatcher, but here he searches the bark of forest trees with microscopic scrutiny for the larvae of insects. We all know the lively black-capped chickadees that fly around in flocks throughout the winter. Sometimes their search for food leads them into the heart of towns and cities, where they are as bold and as much at home as the English sparrow. They also gather around the camps of log-cutters in the forest, become very tame, and plaintively cry for their share in the meals. They remain all the year, nesting in decayed logs, posts, stumps, and even in sides of houses, although they prefer the edge of a wood. If they can find a hole to suit them, very well; if they can't, they will make one. Their devotion to their young is remarkable. A nest in a decayed stump was uncovered, and the mother bird twice taken off by hand, and each time she returned and covered her brood. She uttered no cries or complaints, but devotedly interposed her little form between what must have seemed terrific monsters and her young, and looked at the human ogres with the resolute eyes of self-sacrifice. If she could have known it, the monsters only wished to satisfy their curiosity, and were admiring her beyond measure. Chickadees are exceedingly useful birds, and make great havoc among the insects. "Our next bird is merely a winter sojourner, for he goes north in spring like the kinglet. The scientists, with a fine sense of the fitness of things, have given him a name in harmony, _Troglodytes parvulus_, var. _Hyemalis_." "What monster bird is this?" cried Amy.