The parent birds attracted my attention by appearing with food in their beaks, and by seeming much put out.  Yet so wary were they of revealing the locality of their brood, or even of the precise tree that held them, that I lurked around over an hour without gaining a point on them.  Finally a bright and curious boy who accompanied me secreted himself under a low, projecting rock close to the tree in which we supposed the nest to be, while I moved off around the mountain-side.  It was not long before the youth had their secret.  The tree, which was low and wide branching, and overrun with lichens, appeared at a cursory glance to contain not one dry or decayed limb.  Yet there was one a few feet long, in which, when my eyes were piloted thither, I detected a small round orifice.

As my weight began to shake the branches, the consternation of both old and young was great.  The stump of a limb that held the nest was about three inches thick, and at the bottom of the tunnel was excavated quite to the bark.  With my thumb I broke in the thin wall, and the young, which were full-fledged, looked out upon the world for the first time.  Presently one of them, with a significant chirp, as much as to say, “It is time we were out of this,” began to climb up toward the proper entrance.  Placing himself in the hole, he looked around without manifesting any surprise at the grand scene that lay spread out before him.  He was taking his bearings and determining how far he could trust the power of his untried wings to take him out of harm’s way.  After a moment’s pause, with a loud chirrup, he launched out, and made tolerable headway.  The others rapidly followed.  Each one, as it started upward, from a sudden impulse, contemptuously saluted the abandoned nest with its excrement.

[Illustration:  BARN SWALLOW AND NEST.]

Though generally regular in their habits and instincts, yet the birds sometimes seem as whimsical and capricious as superior beings.  One is not safe, for instance, in making any absolute assertion as to their place or mode of building.  Ground builders often get up into a bush, and tree builders sometimes get upon the ground or into a tussock of grass.  The song-sparrow, which is a ground builder, has been known to build in the knot-hole of a fence rail, and a chimney swallow once got tired of soot and smoke, and fastened its nest on a rafter in a hay barn.  A friend tells me of a pair of barn swallows which, taking a fanciful turn, saddled their nest in the loop of a rope that was pendent from a peg in the peak, and liked it so well that they repeated the experiment next year.  I have known the social sparrow, or “hair bird,” to build under a shed, in a tuft of hay that hung down, through the loose flooring, from the mow above.  It usually contents itself with a half a dozen stalks of dry grass and a few long hairs from a cow’s tail, loosely arranged on the branch of an apple-tree.  The rough-winged swallow builds in the wall and in