In May two boys in town wrote to me to explain to them the meaning of the egg-shells, mostly those of robins, that were to be seen lying about on the ground here and there. I supposed every boy knew where most of these egg-shells came from. As soon as the young birds are out, the mother bird removes the fragments of shells from the nest, carrying them in her beak some distance, and dropping them here and there. All our song-birds, so far as I know, do this.
Sometimes, however, these shells are dropped by blue jays after their contents have been swallowed. The jay will seize a robin's egg by thrusting his beak into it, and hurry off lest he be caught in the act by the owner. At a safe distance he will devour the contents at his leisure, and drop the shell.
The robins, however, have more than once caught the jay in the act. He has the reputation among them of being a sneak thief. Many and many a time during the nesting season you may see a lot of robins mob a jay. The jay comes slyly prowling through the trees, looking for his favorite morsel, when he is discovered by a vigilant robin, who instantly rushes at him crying, "Thief! thief!" at the top of his voice. All the robins that have nests within hearing gather to the spot and join in the pursuit of the jay, screaming and scolding.
The jay is hustled out of the tree in a hurry, and goes sneaking away with the robins at his heels. He is usually silent, like other thieves, but sometimes the birds make it so hot for him that he screams in anger and disgust.
Of the smaller birds, like the vireos and warblers, the jay will devour the young. My little boy one day saw a jay sitting beside a nest in a tree, probably that of the red-eyed vireo, and coolly swallowing the just hatched young, while the parent birds were powerless to prevent him. They flew at him and snapped their beaks in his face, but he heeded them not. A robin would have knocked him off his feet at her first dive.
One is sometimes puzzled by seeing a punctured egg lying upon the ground. One day I came near stepping upon one that was lying in the path that leads to the spring--a fresh egg with a little hole in it carefully placed upon the gravel. I suspected it to be the work of the cowbird, and a few days later I had convincing proof that the cowbird is up to this sort of thing. I was sitting in my summer house with a book, when I had a glimpse of a bird darting quickly down from the branches of the maple just above me toward the vineyard, with something in its beak. Following up my first glance with more deliberate scrutiny, I saw a female cowbird alight upon the ground and carefully deposit some small object there, and then, moving a few inches away, remain quite motionless. Without taking my eyes from the spot, I walked straight down there. The bird flew away, and I found the object she had dropped to be a little speckled bird's egg still warm. I saw that it was the egg of the red-eyed vireo. It was punctured with two holes where the bird had seized it; otherwise it had been very carefully handled. For some days I had been convinced that a pair of vireos had a nest in my maple, but much scrutiny had failed to reveal it to me.
