While some of our birds content themselves with but shallow depressions in the ground, and many others place together so few sticks (and these ill-arranged) that the nest might readily be overlooked, there is one bird that is too lazy to do even so much, but drops an egg in the nest of another bird. This is the habit, too, of the European cuckoo, but our cuckoos are nest-builders, and the bird to which I have referred belongs to a very different group. Few people seem to know it at all, and yet it is abundant over a wide range of country, and has a dozen names, mostly meaningless. The best, perhaps, of them is “cowpen bird,” a name derived, I suppose, from the fact that the bird is often found in pastures where there are cattle or sheep. Indeed, I have often seen them standing upon the backs of cows and sheep, catching flies, I presume, though they seem to be quite inactive when upon such a perch. Although not nest-builders, they have something to do with the building of nests. When that tireless songster the red-eyed vireo builds its pensile nest on the hillside, the necessity for concealment does not occur to the bird, and so its home is often invaded by the female cow-bird, and a single egg dropped into the structure as soon as, if not before, it is finished. Sometimes this is put up with, sometimes not. I have many times found nests that were two-storied, the intrusive egg being, of course, in the basement, and destroyed. This is one of the best examples of bird wit of which I know. A vast deal is taken into consideration while the decision is being reached to build a floor over the obnoxious egg, and so prevent its hatching. There can be nothing of all this ascribed to instinct, for then all such eggs would be destroyed by this means, and the bird become extinct. On the other hand, it is but a very small percentage that have the wit or courage to undertake the work, which is evidence enough that, of a given species of bird, the variation in intelligence among individuals is very marked. This, indeed, we see on every hand when birds are building. Particularly noticeable is it when the female bird stays at home and arranges the material which her mate brings to her. This is mere drudgery to the male bird, and too often worthless bits are brought which the toiling builder promptly rejects, and not always with becoming patience either. She speaks her mind in unmistakable tones, and if not heeded after the second or third scolding, open war is declared on the spot, followed too often by a wreck of all their hopes.