The places selected for this purpose are strange and various. In the wild districts of the West, the birds nidificate in caves that abound in the bluffs along the sea-shore. Near Fort Dallas, Oregon, the basaltic cliffs so common thereabouts are utilized. In the vicinity of Pyramid Lake, Nevada, their nests are placed among the "tufa domes" attached to the roofs of caves, seldom more than one or two pairs being found together. In other localities, in the same section of country, limestone cliffs, crevices of rocks, and sides of wooden bridges, serve the same purposes.

Coming East, where they are much more familiar and confiding, we find quite a change in this particular. Venturing into our crowded cities, they often build their elaborate homes in the porches of dwellings. But the various farm-buildings, which are noticeable in agricultural regions, are generally to be preferred. In such places, the nests are erected on horizontal rafters, or secured to the frameworks, underneath the eaves, after the fashion of the Cliff Swallow's nest. Again, bridges and dilapidated spring-houses are occasionally pressed into service. Besides the foregoing, cases have been cited where the nest of the Cliff Swallow was used, and also one where a small building, of very rude structure—which was temporarily occupied as a blacksmith-shop—was utilized.

Their natural breeding-places, before the settlement of this country, were caves, overhanging cliffs, and like situations. Swallow Cave, at Nahant, was formerly a favorite place of resort. As the country becomes. settled, these places are forsaken for the more convenient ones which the buildings of the farm afford. Such accommodations, experience has shown, tend to a rapid increase in their numbers, for the birds are not slow to perceive the advantages which result from a close familiarity with man.

The nests are constructed of separate layers of mud, from ten to twelve in number, which are often, though not always, parted by strata of fine grasses. The layers themselves are formed of small pellets composed of clay and fine sand, worked over by the birds, and which are adjusted side by side until each layer is complete. The walls being finished, the circumscribed cavity is stuffed with fine soft grass, and is warmly lined with downy feathers. The average height and breadth of such structures when placed on the horizontal rafters of barns is about five inches. The cavity is usually three inches wide at the rim—thus making the thickness of the walls an inch—and about two inches in depth. When placed against the side of a house or of a barn, a strong foundation of mud is usually built, upon which the nest is reared. In that event, the nest is more compactly made, and varies from the preceding, by its more elongate form.

A striking peculiarity of many of these fabrics, is an additional platform which is placed against the nest proper, but wholly distinct therefrom. This is undoubtedly designed as a roosting-place, and is used during the incubating period by the one or the other parent at night, or when not occupied in the procurement of food, or by both when the young have complete possession thereof.

A nest before us which was built upon a horizontal rafter underneath an overshoot, and which may be regarded as typical in the ordinary scientific sense, is composed externally of ten semi-elliptical series of mud pellets, slightly overlapping each other after the manner of tiles, and intercalated with the stems and blades of fine grasses. Similar vegetable materials are found in small quantities on the outside, which serve to strengthen the pellets, thus acting as substantial girders to the entire structure. On the inside is a small layer of the stems of our common timothy grass, which is followed by another of greater compactness, and, finally, by a lining of soft meadow grass. The entire length of this nest is four inches, and it gradually tapers from above downwards, giving the appearance of a longitudinal section of an inverted cone. The depression is two and a half inches wide in one direction, about four in the line of greatest width, and scarcely an inch in depth, the shallowness being compensated for by the greater length transversally.

The Plate represents a nest which is nearly the exact counterpart of the one just described, differing immaterially therefrom in the lack of grasses between the layers of mud on the outside, and in having a lining of feathers. The dimensions are about the same in the original, but have been somewhat reduced in the cut, owing to the size of the page. The female is shown upon the edge of the nest, peering therein, while her stronger half is on the wing, and evidently homeward-bound. In the natural position this elaborate structure was completely protected by the eaves of the building against which it reposed, but in order to show the inner arrangement, as well as the eggs in situ, the artist was compelled to leave it partially exposed.

The nest being completed, two or three days elapse before the female is ready to deposit her first egg. Having commenced, she continues to do so, at the rate of one a day, until her full number is laid, which, according to what shall constitute her complement, requires from four to six days. Incubation immediately succeeds, and lasts for eleven days. This is not exclusively the work of the female. Sometimes her affectionate husband relieves her for awhile. But when not thus employed, he occupies his spare moments either in fetching her some dainty article of meat, or in guarding his home from intrusion. Few species show less dread of man during these times. Such is the confidence which is reposed in him, that the sitting-bird will keep to the nest, and allow him to pass within a few feet of her. But, on the other hand, if any interference is attempted, she glides noiselessly out, and watches and contemplates his movements with few, if any, murmurs of complaint.

An interesting account is given of these birds by Mr. J. K. Lord. While he and his party were encamped at Schyakwateen, in British Columbia, a small shanty, loosely constructed of poles, and tightly roofed, was erected, and used as a blacksmith's shop. Early one morning, late in June, they were visited by a pair of Swallows, who instantly perched on the roof of this shed, unmindful of the noise of the bellows, or the showers of sparks that flew around. Presently they entered the house, and commenced an examination of the roof and its supporting poles, twittering to each other the while, in the most animated manner. At length the matter appeared to be settled, and on the ensuing day they commenced the erection of a building on one of the poles directly over the anvil. Though the hammer was constantly passing close to the structure, yet the fearless builders kept steadily at work, and in about three days had completed the rough outline thereof. A few days more, and their home was ready for occupancy. The narrator often stationed himself upon a log to watch them, with his face so near, that their feathers frequently brushed against it as they toiled at their task. Suffice it to say, the eggs were laid, the young hatched and successfully reared, and the trustful pair maintained their serenity and fearlessness till the last.

The attentions of the parents to their young are unremitting. The number of small insects which they collect for them is almost incredible. Flies, aquatic larvæ, and small moths form a considerable part of their earliest diet. But as they become older, other insects are added to their bill of fare. When about fourteen days old they are able to leave the nest. The manouvres of the parents to entice them out, and the assistance which they render them in their first feeble attempts at flight, are among the most curious and interesting of all our ornithological experiences. A few days' training gives them complete control over their alar appendages, and they are soon as merry and happy as any of their older companions, as they sail through the air in quest of insects, or in the pursuit of pleasure. By the first of September, they are strong enough to endure the fatigue incident to the long journey which they are called upon to make, in obedience to the supreme law of their being, at this season of the year.