The key to the behavior of the birds in this respect may be found in the Darwinian theory of natural selection. From the first settlement of the country a few of the common birds, attracted by a more suitable or more abundant food-supply, or other conditions, must inevitably have nested near human dwellings. These birds would thrive better and succeed in bringing off more young than those that nested in more exposed places. Hence, their progeny would soon be in the ascendancy. All animals seem to have associated memory. These birds would naturally return to the scenes and conditions of their youth, and start their nests there. It would not be confidence in men that would draw them; rather would the truth be that the fear of man is inadequate to overcome or annul this home attraction. The catbird does not come to our vines on the veranda to nest from considerations of safety, but because her line of descent runs through such places. The catbirds and robins and phœbe-birds that were reared far from human habitations doubtless return to such localities to rear their young. The home sense in birds is strong. I have positive proof in a few instances of robins and song sparrows returning successive years to the same neighborhood. It is very certain, I think, that the phœbe-birds that daub our porches with their mud, and in July leave a trail of minute creeping and crawling pests, were not themselves hatched and reared in the pretty, moss-covered structure under the shelving rocks in the woods, or on the hillsides.