The circumstance of the bluebirds being emboldened by the cold, suggests the fact that the fear of man, which now seems like an instinct in the birds, is evidently an acquired trait, and foreign to them in a state of primitive nature. Every gunner has observed, to his chagrin, how wild the pigeons become after a few days of firing among them; and, to his delight, how easy it is to approach near his game in new or unfrequented woods. Professor Baird tells me that a correspondent of theirs visited a small island in the Pacific Ocean, situated about two hundred miles off Cape St. Lucas, to procure specimens. The island was but a few miles in extent, and had probably never been visited half a dozen times by human beings. The naturalist found the birds and water-fowls so tame that it was but a waste of ammunition to shoot them. Fixing a noose on the end of a long stick, he captured them by putting it over their necks and hauling them to him. In some cases not even this contrivance was needed. A species of mocking-bird, in particular, larger than ours, and a splendid songster, made itself so familiar as to be almost a nuisance, hopping on the table where the collector was writing, and scattering the pens and paper. Eighteen species were found, twelve of them peculiar to the island. Thoreau relates that in the woods of Maine the Canada jay will sometimes make its meal with the lumbermen, taking the food out of their hands. Yet, notwithstanding the birds have come to look upon man as their natural enemy, there can be little doubt that civilization is on the whole favorable to their increase and perpetuity, especially to the smaller species. With man come flies and moths, and insects of all kinds in greater abundance; new plants and weeds are introduced, and, with the clearing up of the country, are sowed broadcast over the land. The larks and snow-buntings that come to us from the North, subsist almost entirely upon the seeds of grasses and plants; and how many of our more common and abundant species are field-birds, and entire strangers to deep forests? In Europe some birds have become almost domesticated, like the house-sparrow, and in our own country the cliff-swallow seem to have entirely abandoned ledges and shelving rocks, as a place to nest, for the eaves and projections of farms and other out-buildings.