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Cliff Swallow

These swallows are known for their large flocks and social behavior.

Very widely distributed in North America, and very colonial when nesting, the Cliff Swallow’s gourd-shaped mud nests are a common sight under bridges and culverts. Cliff Swallows are known to parasitize each-other’s nests.

Cliff Swallows get quite physical when fighting for nest sites, and often chase each other after wrestling. The same colony site may be used in subsequent years, but sometimes sites go unused for one or more years before the birds return to breed.


Description of the Cliff Swallow


The Cliff Swallow has brownish-blue upperparts, pale underparts, a dark throat, reddish cheeks, and a pale collar and forehead.  In flight, a reddish rump is prominent.  Length: 5 in.  Wingspan: 13 in.


Sexes similar.

Seasonal change in appearance



Juveniles are similar to adults, but browner in the face.


Cliff Swallows inhabit farms, lakes, bluffs, and open country.


Cliff Swallows primarily eat insects, but also, rarely, berries.


Cliff Swallows forage by capturing prey in flight using their open mouth.


Cliff Swallows breed in most areas from Alaska to Mexico. They winter in South America. The population is stable.

More information:

Bent Life History

Visit the Bent Life History for extensive additional information on the Cliff Swallow.

Wing Shape

The shape of a bird’s wing is often an indication of its habits and behavior. Fast flying birds have long, pointed wings. Soaring birds have long, broad wings. Different songbirds will have a slightly different wing shape. Some species look so much alike (Empidonax flycatchers) that scientists sometimes use the length of specific feathers to confirm a species’ identification.

Wing images from the University of Puget Sound, Slater Museum of Natural History

Fun Facts

Cliff Swallows are extremely social, nesting in colonies of up to 3,500 pairs.

Cliff Swallows once nested on cliffs, but today are nearly always found on artificial structures such as bridges and culverts.


The typical song consists of squeaky twittering


Similar Species

Barn Swallow

Barn Swallows have deeply forked tail.  Underparts range from dark rusty red to pale rusty color.

Cave Swallow
Cave Swallows have a reddish forehead patch, and other swallows lack the reddish rump.


The Cliff Swallow’s nest is a gourd-shaped shell of mud attached to the underside of a bridge, culvert, or the side of a cliff.

Number: Usually lay 3-5 eggs.
Color: White or pinkish-white with darker markings.

Incubation and fledging:
The young hatch at about 13-15 days and fledge at about 23-26 days, though remaining dependent on the adults for another several days.


Bent Life History of the Cliff Swallow

Published by the Smithsonian Institution between the 1920s and the 1950s, the Bent life history series of monographs provide an often colorful description of the birds of North America. Arthur Cleveland Bent was the lead author for the series. The Bent series is a great resource and often includes quotes from early American Ornithologists, including Audubon, Townsend, Wilson, Sutton and many others.

Bent Life History for the Cliff Swallow – the common name and sub-species reflect the nomenclature in use at the time the description was written.



The generic name of the cliff swallow, Petrochelidon, is derived from the Greek petra, a rock, and chelido’n, a swallow, and its specific name is from the Latin albus, white, and frons, forehead; hence a rock swallow with a white forehead.

There are two common names of this swallow alluding to its nesting site that vie with each other for popularity; they are cliff swallow and eaves swallow. The former, although less appropriate in many sections of its nesting range today, is the one adopted by American ornithologists. Less commonly used names originating from the character of the nests or building material are jug swallow, mud r~wallow, pipe swallow, and mud dauber. It is not surprising that the plumage of this well-marked swallow has given rise to such appellations as crescent swallow, white-fronted swallow, and square-tailed swallow. Another common name, which was widely used by the earlier ornithologists but seldom applied today, is republican swallow. This unusual name originated with Audubon (1831) when he first discovered the species at Henderson on the banks of the Ohio River in the spring of 1815. lIe writes: “I drew up a description at the time, naming the species Hirundo republicana, the republican swallow, in allusion to the mode in which individuals associate, for the purpose of forming their nests and rearing their young. ~ The cliff swallow ranks well among our most abundant birds and has a breeding range extending from Mexico to Alaska and across the continent from the Pacific to the Atlantic coast lines. In spite of its present-day abundance and wide distribution, it was unknown to Wilson and other early ornithologists. Its history although obscure is of unusual interest.

This swallow was first brought to our attention by John Reinhold Forester who refers to it as Hirundo 35 in an account of the birds sent from Hudson’s Bay published in the Philosophical Transactions in 1772. Forester gave it no name, and it was left for Thomas Say to name and describe the species from a type specimen taken in 1820 on Long’s Expedition to the Rocky Mountains, an account of which, compiled by Edwin James, was published in 1823.

In the same year (1820) it was also discovered in the Rocky Mountains by Sir John Franklin’s party between Cumberland House and Fort Enterprise and on the banks of Point Lake in latitude 65g. In June 1825 a number of these birds made their appearance at Fort Chippewyan and built their nests under the eaves of the house. This fort had then existed many years, and trading posts had ken in existence a century and a half, and yet this was the first instance, according to Baird, of the bird placing itself under the protection of man throughout that wide extent of territory. Audubon (1831) first saw this bird at Henderson in 1815, and two years later he found a colony breeding at Newport, Ky., which dated back to the same year. In 1837 Brewer (Baird, Brewer, and Ridgway, 1905) received the eggs of this swallow from Coventry, Vt., where they were known as “eave” swallow, perhaps the first instance of the application of this common name. The date at which the Vermont colony appeared could not be determined. Brewer saw them for the first time in 1839 at Jaifrey, N. H., where they appeared the year before. The same year they were noted in Burlington, Vt., where they had been known for only three years. A large colony was observed in Attleborough in 1842. In the same year they also appeared apparently for the first time in Boston, Hingham, and other places in the neighborhood.

In 1824 DeWitt Clinton stated he had met them at Whitehall, N. Y., at the southern end of Lake Champlain in 1817 about the time of their first appearance on the Ohio noted by Audubon. At about this time they were seen for the first time at Randolph, Vt. These swallows were seen for the first time in Winthrop, Maine, in 1830 and at Carlisle, Pa., in 1841.

In 1861 Prof. A. E. Verrill discovered a large colony of these birds building on the high limestone cliffs of Anticosti Island, in the Gulf of St. Lawrence. Since this appeared to be a long-established colony and far removed from civilization, Verrill was led to believe that the extension of the range of the cliff swallow was not of a recent date. An inquiry that he conducted revealed that they were known in Maine long before they were discovered in the West, and he concluded that they were not indigenous in the West. The fact that they were not seen by the early ornithologists proves nothing; there is little doubt that they were nesting in remote situations of eastern North America when civilized man appeared.

One thing is apparent: as the land of New England was cleared for fields and pastures, and as barns with wide eaves were erected, the cliff swallows, finding an abundance of food and sheltered places for their nests, left their primitive environment of isolated cliffs to come in close association with man. Under these new conditions the birds multiplied and spread from place to place where they had not been seen before. It is also possible that there was an eastward movement later from the cliffs and bluffs of the West, but for this there is no concrete evidence.

In more recent years the prosperity of the cliff swallows in their newly acquired environment has suffered. Such factors as the invasion of English sparrows, the improvement and painting of barns, and the desire of owners to rid their buildings of the mud nests have affected the local fluctuations in the number of these valuable and attractive birds.

So serious was the decrease of these birds in New Jersey where formerly they were abundant that the New Jersey Audubon Society under the leadership of W. DeWitt Miller proposed a campaign by the society for increasing the summer resident cliff swallows in New Jersey (Bowdish, 1930). Miller considered modern barns offering poor support for nests and molestation by thoughtless boys and men as factors contributing to the decrease. The plans of the society were announced in its bulletin and made public through news items sent to the press. A survey of nesting colonies was made, and suggestions, anch as nailing plates to the ends of the rafters of barns to afford more dependable supports for the nests and providing a readily available mud supply, were made. The value of the swallows was also impressed on owners of buildings where colonies were located. Furthermore, prizes were offered for the three largest colonies. I have seen no reports of the effectiveness of the campaign, but it is at least an interesting project in connection with the history of this species.

Spring: The first cliff swallows reach northern Mexico and our Southwestern States during the last week of March. From this region the wave of migration is exraordinary from the standpoint of its speed up the Pacific coast and its lag in the southeastern part of the United States. It has long been known that the earliest records always come from California where it usually becomes common long before it has been observed in Texas, the Gulf States, and Florida. By March 20, when the vanguard has not quite reached the lower Rio Grande in Texas, the species is already north of San Francisco, Calif. Lincoln (1939) presents a plausible explanation of this ornithological puzzle by pointing out that the cliff swallow goes around the Gulf of Mexico rather than across it. He states further: “The reason for this circuitous route around the Gulf of Mexico lies in the fact that the cliff swallow is a day migrant and catches its daily ration of winged insects as it travels slowly along in the proper direction, which obviously it could not do if its route were across the Gulf of Mexico.” By the first week of May the cliff swallows have reached New England, and at about the same time they appear in Alaska again, forcibly emphasizing the rapidity of the migration wave along the Pacific coast and the comparatively slow progress along the Atlantic seaboard. Lincoln makes a very illuminating comparison of the migration of the cliff swallow and the blackpoll warbler as follows:

During the winter months these species are together in South America. Upon the approach of spring, bringing with it the impulse to start northward toward their respective breeding grounds, the warblers strike straight across the Caribbean Sea to Florida, while the swallows begin their journey by a flight of several hundred miles westward to Panama. Thence they move leisurely along the western shore of the Caribbean Sea to Mexico, and as if to avoid a long trip over water, go completely around the western side of the Gulf of Mexico. By making this long circuitous flight, swallows that nest in Nova Scotia add more than 2,000 miles to the length of their migratory journey. The Question may be asked: Why should the strong-winged cliff swallow use a route that Is so much longer and more roundabout than that followed by the Black-Poll Warbler? The explanation is simple as the swallow is a day migrant while the warbler travels at night. The migration of the warbler is made up of a series of long nocturnal flights, alternated with days of rest and feeding. The swallow, on the other hand, starts its migration several weeks eariler and catches each day’s ration of flying Insects during a few hours of aerial evolutions, which at the same time carry it slowly in the proper direction. Flying along the insectteeming shores of the Gulf of Mexico, the 2,000 extra miles that are added to its migration route are hut a fraction of the distance that these birds actually cover in pursuit of their food.

While a considerable number of cliff swallows have been banded there are not sufficient returns to assist in plotting the actual migration routes. One record, however, is of interest: A cliff swallow banded at Dell Rapids, S. Dak., on June 14, 1937, was captured and released with its band at Gbent, W. Va., on July 16, 1987. This, bird in the course of a month flew approximately 1,200 miles in a southeasterly direction. If we take into account its erratic and circuitous flights in quest of insects during its journey, it probably averaged more than 100 miles a day. Its flight to the eastward is interesting, since it migrates to its winter home in South America via Mexico and Central America. One record, however, is not sufficient to indicate that many individuals travel so far out of bounds of a direct route.

The cliff swallow migrates in flocks, and practically all the reports of the large numbers seen throughout the migration route mention the association of the cliff swallow with barn and tree swallows as well as other members of the family. At Rowland’s Marsh in the Sierras, Ray (1918) saw on May 27, 1912, at least a thousand cliff swallows in migration. The birds rested for a time in the same grove of dead pines where large numbers of tree swallows had been observed. Knight (1905) describes an interesting observation he made of fatigued migrating cliff swallows at Bangor, Maine, on May 17. “They were perched by hundreds in low shrubs and bushes between the Bicycle Path and a flooded meadow just beyond. Some small willow bushes were each occupied by fifty or more Swallows, whose drooping, half-spread wings and open beaks, through which they drew spasmodic gasps of air, were a most eloquent testimonial of the fact they had just arrived from a long journey and were exceedingly fatigued.”

The route of migration takes the cliff swallow over thousands of arduous miles of travel, but nevertheless their arrival is remarkably punctual, sometimes varying but a day or two from the expected time, a fact readily verified by any one who observes the appearance of the birds at the nesting colonies. The arrival of the cliff swallows at the colony located on the walls and arches of the old San Juan Capistrano Mission in southern California has been given great publicity and in recent years has even been the subject of radio broadcasts. It has been claimed that the birds never vary from March 19; even the hour of their arrival has been said to be constant. Ornithologists who have checked these assumptions have found that the swallows are not infallible to such extravagant claims.

Courtship: The courtship of cliff swallows is carried on simultaneously with their early nesting activities and especially in places where the birds are busily engaged in gathering the mud used in the construction of their homes. The two following accounts of observations made in widely separated sections of the country will serve to illustrate their interesting behavior at such times. Brewster (1938) in his journal of the birds of the Umbagog region vividly describes the activities of cliff swallows he observed in that retreat on June 8, 1909, as follows:

This morning as I was watching the birds I saw two come together In the air and whirl around and around straight down to the ground, where they remained for more than a minute, in what I took to be sexual union, waving and fluttering their wings like butterflies. The other members of the colony seemed actively interested In the affair, and, indeed not a little excited about it, for they collected over the prostrate birds and dashed down almost to them, with loud cries. When the pair finally separated, one bird flew off in one direction and the other In another. I do not think it could have been a fight, for Eave Swallows are among the most peaceable and social of all birds and I have never known them to show the slightest tendency to quarrel.

Wetmore (1920) describes the activities of cliff swallows he observed in New Mexico as follows:

On June U they were building nests on the sandstone cliff above the Laguna de la Puerta. The birds came down to the lake shore in Utile bands of ten or a dozen and alighted close together with trembling wings extended at an angle from their backs, standing high on their legs to avoid soiling their feathers. After allghting they leaned over, filled the mouth with mud with on~ or two sharp digs and then rose to fly hack up the steep slopes to the colony. Iteles frequently alighted on the backs of the females as they gathered mud and copulation took place while the birds were on the ground.

Nesting: The nests of the cliff swallow are cleverly constructed of pellets of mud or clay, are roofed over, and generally assume a flask, retort, or bottle shape with a narrow entrance leading into an enlarged chamber. The protruding neck of the nest varies greatly, from some 5 or 6 inches long, or even longer, to others that have no neck, or even to an open structure approaching the barn swallow type of nest. The cliff swallow may strengthen the walls of its plastic home by the use of straws and horsehair, but such materials are not so freely used as they are in the nests of the barn swallow. As a result the former are more friable and are subject to a greater amount of erosion and breaking, especially if they become dampened during times of heavy rainstorms. The chamber of the nest is scantily lined with a few dried grass stems to which a few feathers and other materials are sometimes added.

The cliff swallows are gregarious in their nesting habits, and it is exceptional to find isolated nests far distant from others of the species. The primitive nesting sites of this swallow are in ïvarious situations afforded by bluffs, cliffs, and the perpendicular walls of deep gorges in remote mountainous sections of its nesting range, and many of them continue to nest in regions where such situations prevail. Many of the largest colonies, some of them comprising thousands of nests, are located on cliffs. The cliff swallow, however, is a plastic, adaptable species that has been quick to accept new and very different situations provided by civilized man and thus has materially increased its range as well as its numbers. They have accepted the great concrete dams, erected by man in the construction of power projects, which are the nearest approach to the primitive sites used by these cliff dwellers. Today, especially in the eastern parts of its nesting range, this swallow is associated with the eaves of houses and barns, where its friable nests are better protected from rainstorms, but this has also made them subject to greater molestation by such enemies as the English sparrow. In New England it is unusual to find them nesting on cliffs. Although I have visited more than 50 populous colonies in New England and the Maritime Provinces I have seen only one located on a cliff. So general has this change in habitat been established that the name eaves swallow is considered a much more appropriate designation of the species. In cases where the birds have been given human encouragement the colonies located on barns often vie in numbers with those located on cliffs. Christensen (1927) has published a photograph of a colony located on his barn in Newark, Nebr., that contained 800 nests. Other colonies of similar size have been noted. The nests located on buildings are usually on old unpainted structures where it would be expected that the pellets of mud would adhere much better to the rough surface. Nevertheless, pa4nted buildings are utilized in numerous Instances.

Not only has the cliff swallow sought out the sites afforded by buildings of isolated farms and camps, but it has even invaded the cities and there built its nests on private homes and public buildings located on busy thoroughfares. Gould (1906) reports that cliff swallows built their nests on the store of Woodman, True & Co. of Portland and also under the eaves of the Portland Savings Bank; and I counted 42 nests located under the gables and eaves of a church at Popham Beach, Maine. Old missions in California, such as the famous San Juan Capistrano, constantly visited by swarms of tourists, are occupied by these confiding swallows. Nor are they adverse to the environment afforded by a large university campus. Grinnell (1987) and others have had much to report concerning the existence and life of a large colony that has taken up its residence on the concrete walls of the Life Sciences Building of the University of California at Berkeley. Burleigli (1930) reports their nesting on one of the buildings of the campus of the University of Washington.

The further adaptability of this bird is shown in its ability to meet a situation when the usual nesting sites are not available. Dawson (1923) writes: “Both Grinnell and Willett have recorded how the Cliff Swallows of Bear Valley, hard put to it for nesting sites in an otherwise delectable country, attached their retorts to the sides and under surfaces of great pine trees.” A photograph published by Dawson (1923) shows a colony of nests on a yellow pine taken at Bear Lake in the San Bernardino Mountains of California. The nests are i~estricted to clusters concentrated on the trunk beneath the larger branches of the tree where they are better protected from rains. Nuttall (1832) states that cliff swallows build in trees along the Columbia River.

When the cliff swallows resort to buildings they usually plaster their nests under the protecting eaves on the outside of the structures but not infrequently they may enter the building. Evermann (1886) writes: “A colony of more than a hundred pairs nested in a shed in Santa Paula (California). The nests were fastened to the rafters, much after the manner of the Barn Swallow. Many horse-hairs were plastered into the nests and these often caused the death of the builders. I took from this shed some six or eight birds which I found hanging about the nests, they having gotten entangled in the hairs.” Johnson (1900) found the retort-shaped nests against or under the beams inside a barn. Some of the nests were built against the hay which served as a back for the nest. Johnson states: “The season was a very wet, rainy one which accounts for the change from eaves outside, where they usually built.” McCann (1936) found cliff and barn swallows nesting together, one nest of the cliff swallow was within 12 inches of a barn swallow’s nest. Goodsell (1919) also noted cliff and barn swallows nesting together using old foundations of one another’s nests. Whittle (1922) describes an interesting case in which a cliff swallow utilized a robin’s nest built on two telephone wires entering a building. The nest of the swallow was not in contact with the building but merely began at the rim and domed over the old robin’s nest. At Frenchman’s River, Canada, Potter (1932) discovered that cliff swallows had taken possession of the interior of an old freight car.

Not only do these birds select sites on the outside and inside of buildings and various structures but they may also nest underneath them. An enormous colony of cliff swallows nested on the piling under an old building at the edge of the water at Clear Lake, Calif. Kobb~ (1900) found many cliff swallows nesting in caves on the ocean side of Cape Disappointment, Wash. Dice (1918) found the nests in a road tunnel under the railroad tracks near Lamor, Wash. Townsend (1917) states that cliff swallows have been known to breed in the abandoned burrows of bank swallows, and Carpenter (1918) found several cases of typical bottleneck mud nests built over entrances to old rooms of bank swallows at Oceanside, Calif. In one instance the eggs of the cliff swallow were found at the end of a 2-foot tunnel lying in a typical seaweed nest of the bank swallow.

The cliff swallow has also proved its great versatility in coping with unusual situations. Hales (1904) tells of an attempt of cliff swallows to build under the eaves of a barn where there was no projecting object to serve as a foundation for a nest, which. resulted in repeated failures. One resourceful pair took advantage of a weatherstrip over a door and built an enormous cylinder tube, which they filled with straw to a height of 18 inches, allowing just enough room for a beautifully shaped nest at the top. The birds were awarded suceess in bringing forth their brood of young. The following two instances further illustrate how the cliff swallow is able to meet with unusual conditions. Reed (1927) relates a case of a cliff swallow’s nest built over a back door of a home where there was a constant traffic of persons and a slamming of the screen door. After the young had hatched the nest crumbled and fell with the young to the floor. The young were placed in a strawberry box hung up where the nest had been plastered. The adult birds at once proceeded to cover the box with mud to protect and conceal the young, which were suceessfully reared. The following year the pair returned and repaired the strawberry basket, but after an egg was mysteriously destroyed they made over a phoebe’s nest and successfully reared their brood there. Wright (1924) cites a similar case in which the young of a fallen nest were placed in a tin can nailed to the barn. The birds returned at once and built a neck of a nest over the opening of the can.

Clif swallows are not averse to nesting in the proximity to the nests of other larger birds. Forbush (1929) records a case where the nests were built among the outer sticks of a great blue heron’s nest. Coues (1878), Taverner (1919), and Forbush (1929) cite cases where nests of the cliff swallow were built on the cliffs about prairie falcons’ nests. Taverner also found them about a duck hawk’s nest. Apparently they lived in harmony and were not disturbed by these larger predacious species.

It has been observed by Taverner (1928) and others that the nests of large colonies of cliff swallows located on cliffs are situated in sites least affected by heavy rains. Mr. Taverner’s account of such a colony located on the cliffs of the Red Deer River, Alberta, Canada, is as follows:

This river bed is sunk from two to three hundred feet below the main prairie level and in many cases the valley walls approach the river bank in irregular, and more or less sheer, cliffs. Many wall spaces thus formed are sites of large colonies of nesting cliff swallows that plaster their gourd-like nests closely together making continuous mud-incrustations over considerable surfaces. The boundaries of these aggregations of nests are often very definite but to the casual observer often erratically arbitrary in outline and extent. Many groups of nests are obviously under sheltering overhangs, but others seem well out into the open and subject to the Inciemencies of every weather. Often there is no opparent reason why nests should be huddled closely together as if space were very precious and then cease at an imaginary line beyond which conditions seem equally, or even more, desirable.

When the rains come, however, darkening the exposed faces of the cliffs with their wetness, much of the mystery is explained. In practically every case it is then seen that the nest colonies occupy only the dry spots of the irregular, and generally wet, surfaces and that the soluble, fragile nest-structures often cease almost on the line of moisture. Most of these colonies seem to be occupied only for a single season or a short series of years and new sites are selected at frequent intervals; consequently there are everywhere old and deserted nest groups in various stages of delapidation whose obvious age bespeaks their permanency and the good judgment with which they were founded as regards prevailing weather, wind and rain. One mild shower and wetting would be sufficient to dissolve their clayey structure into its constituent gumbo to drop with unctuous splash to the talus below or to flow away in stalactites of sluggish mud.

It does not seem that this safety of situation Is generally achieved by a system of trial and error for few ruins of recent and obvious errors are noted as would be were that the case. By some means Cliff Swallows after nesting under such condition for countless generations have evolved methods of nestsite selection that nearly unerringly pick out amid the multitudinous wall exposures and tricky wind currents of the canyons the safe situations. There is no necessity here at least to defer nest making until a mud-making rain supplies structural material and coincidentally marks out the safety zones on the cliffs for the river supplies them constantly, irrespective of weather, a source of the choicest mud, and building can be undertaken at any time. Swallows also generally like to carry on their work in bright sun and a drying atmosphere that fixes the growing sub-structure before further accretions are added. It may be however that the site is decided upon during or immediately after a shower and perhaps the foundation is outlined before the drying cliffs lose their tell-tale moisture and is then left to be completed in better building weather. Howevee it is, whether occult instinct or empirical methods guide the birds, there is here shown a most interesting adaptation to environment.

The activities about a colony of cliff swallows during the time of nest building are fascinating. Such a scene has been admirably described by Coues (1878) in his account of the cliff swallows observed in the Colorado Valley:

Suddenly they appear: quite animated and enthusiastic, but undecided as yet; an impromptu debating society on the fly, with a good deal of sawing the air to accomplish, before final resolutions are passed. The plot thickens; some Swallows are seen clinging to the slightest inequalities beneath the eaves, others are couriers to and from the nearest mud-puddle; others again alight like feathers by the water’s side, and all are in a twitter of excitement. Watching closely these curious sons and daughters of Israel at their ingenious trade of making bricks, we may chance to see a circle of them gathered around the margin of the pool, insecurely balanced on their tiny feet tilting their tails and ducking their heads to pick up little “gobs” of mud. These are rolled round in their mouths till tempered, and made like a quid into globular form, with a curious working of their jaws; then off go the birds, and stick the pellet against the wall, as carefully as ever a sailor, about to spin a yarn, deposited his chew on the mantel-piece. The birds work indefatigably; they are busy as bees, and a steady stream flows back and forth for several hours a day, with intervals for rest and refreshment, when the Swallows swarm about promiscuously a-flycatching. In an incredibly short time, the basement of the neat is laid, and the whole form becomes clearly outlined; the mud drys quickly, and there is a standing place. This is soon occupied by one of the pair, probably the female, who now stays at home to welcome her mate with redoubled cries of joy and ecstatic quivering of the wings, as he brings fresh pellets, which the pair in closest consultation dispose to their entire satisfaction. In three or four days, perhaps, the deed is done; the house is built, and nothing remains but to furnish it. The poultry-yard is visited, and laid under contribution of feathers; hay, leaves, rags, paper, string: swallows are not very particular: may be added; and then the female does the rest of the “furnishing” by her own particular self. * ï ï Seeing how these birds work the mud in their mouths, some have supposed that the nests are agglutinated, to some extent at least, by the saliva of the birds. It is far from an unreasonable idea: the chimney swift sticks her bits of twigs together, and glues the frail cup to the wall with viscid saliva; and some of the Old World Swifts build nests of gummy spittle, which cakes on drying, not unlike gelatine. Undoubtedly some saliva is mingled with the natural moisture of the mud; but the readiness with which these Swallows’ nests crumble on drying shows that saliva enters slightly into their composition: practically not at all: and that this fluid possesses no special viscosity. Much more probably, the moisture of the birds’ mouths helps to soften and temper the pellets, rather than to agglutinate the dried edifice itself.

The details of mud gathering and nest building are described by Audubon (1831):

About day-break they flew down to the shore of the river, one hundred yards distant, for the muddy sand of which their nests were constructed, and worked with great assiduity, until near the middle of the day, as if aware that the heat of the sun was necessary to dry and harden their moist tenements. They then ceased from labour for a few hours, amused themselves by performing aerial evolutions, courted and caressed their mates with much affection, and snapped at files and other insects on the wing. They often examined their nests to see if they were sufficiently dry, and as soon as they appeared to have acquired the requisite firmness, they renewed their labours. Until the females began to sit, they all roosted in the hollow limbs of the Sycamores (PLatanu8 occiJen~aUa) growing on the hank of the Licking River, but when incubation commenced, the males alone resorted to the trees. A second party arrived, and were so hard pressed for time, that they betook themselves to the holes in the wall, where bricks had been left out for the scaffolding. These they fitted with projecting necks, similar to those of the complete nests of the others.

Brown (1910) describes briefly but well the mud-gathering habits of cliff swallows he observed at Grand Pro, Nova Scotia:

In one place was a trench dug some five feet deep, and with a most Inviting bed of soft sticky clay at the bottom. The Swallows were making the most of the opening of such a mine, and, through the entire forenoon that I observed them, they flocked in numbers and worked most conscientiously. * They came in eager succession, fluttering down, feet dropped, ready to settle lightly on the soft mud. The moment the feet touched ground, the body and tail were well up, so as not to soil those sleek feathers, and the wings extended straight over the back, continually fluttering to keep the feet from sinking or sticking. Mouthfuls of clay were quickly gathered, the wings continually shaking, and soon the Swallow was off. Every one was busy, mostly mindful only of his own affairs but now and then a tiff occurred, where two wanted the same spot. Every newcomer called softly, and those flying above and across were musically happy.

Knowlton (1881) made some interesting observations on cliff swallows at Brandon, Vt., in which it is clear that in the life of the swallows incidents occur that parallel those in a human society. He says:

One day, while watching them, I noticed one bird remained in her halffinished nest, and did not appear to be much engaged. Soon a neighbor, owning a nest a few feet away, arrived with a fresh pellet of clay and, adjusting it in a satisfactory manner, flew away for more. No sooner was she out of sight than the quiet bird repaired to the neighbor’s nest, appropriated the fresh clay and moulded it into her own nest! When the plundered bird returned, no notice was taken of the theft, which was repeated as soon as she was again out of sight. I saw these movements repeated numerous times, but was called away. and when I again returned both nests were completed.

In the same place a nest remained undisturbed, and was occupied by probably the same pair of birds for several seasons. This spring they returned to the old nest, and all appeared prosperous, until one day I noticed a number of Swallows engaged in walling up the entrance of this old nest. This, and the outline of a new nest over the old, was soon completed. I then broke opea the closed nest and found within the dead body of a Swallow. This bird had probably died a natural death, and the friends being unable to remove the body, and knowing it would soon become offensive, adopted this method of sealing it up.

Occasionally three swallows may be seen engaged in building one nest. E. 0. Grant (Forbush, 1929) watched a nest at Long Lake, Allegash, Maine, that was built by three birds, and he says that they all took turns in incubating the eggs. He believed them to be two males and a female. Brewster (1906) in his study of cliff swallows in the Cambridge region of Massachusetts found as a rule two birds in each nest, but several of the nests he examined sheltered three birds each. Brewster concludes that there is good reason to suspect that cliff swallows sometimes practice polygamy or polyandry.

The time required to build a nest varies a great deal with different pairs of birds, at least as reported by various observers. Knight (1901) ststes that 10 to 14 days are required to finish the nest. In my own experience in watching the building of a nest in a colony at Kent Island, Bay of Fundy, 5 days elapsed from the time the first pellets of mud were applied to the time the nest was ready for its lining. Three days later the first egg was laid. Ordinarily it requires a week for nest construction but the weather conditions, mud supply, and amount of disturbance are factors that will materially affect the length of time.

Most all observers agree that cliff swallows in general raise two broods of young during any one breeding season. Hatch states that even three broods are sometimes reared, but I am inclined to believe that is very exceptional.

The incubation period varies from 12 to 14 days according to various authorities. The time that elapsed from the date of the laying of the last egg to the hatching of the first young in a nest which I observed at Kent Island was 13 days.

Eggs: [AUTHOR’S NOTE: The number of eggs in a complete set varies from three to six, but four or five eggs constitute the usual complement. They vary in shape from ovate to elliptical-ovate, or rarely to elongate-ovate. The ground color is white, creamy white, or pinkish white. Some eggs are evenly, either sparingly or thickly, marked with fine dots or small spots, or a mixture of both; and some have a few small blotches. In some the markings are concentrated at the larger end or coalesced elsewhere into a dense wreath. The markings are in various shades of light and dark browns, or “brownish drab,” with underlying spots or small blotches in the paler shades of “Quaker drab.” Very rarely the eggs are entirely unmarked. The measurements of 50 eggs average 20.3 by 13.9 millimeters; the eggs showing the four extremes measure 22.9 by 14.2, 22.4 by 15.2~ 17.3 by 13.2, and 18.8 by 12.7 millimeters.]

Plumages: Brewster (1878) has described the juvenal or first plumage from a male specimen taken at Upton, Maine, July 27, 1874: “Top of head, back and scapulars dark brown; collar around nape, dull ashy, tinged anteriorly with rusty. Rump as in adult, but paler; forehead sprinkled with white, and with a few chestnut feathers. Secondaries broadly tipped with ferruginous. Throat white, a few feathers spotted centrally with dusky. Breast and sides ashy, with a rusty suffusion, most pronounced on the latter parts. A very small area of pale chestnut on the cheeks.” This plumage is retained by the birds until they have migrated to their winter quarters.

According to Dwight (1900) the first winter plumage is acquired by a complete postjuvenal molt in the winter habitat. When the birds return the following spring wear is evident in the wings and tail although the resistant metallic feathers show little of it. In this plumage the birds acquire a glossy blue head and back and the rich chestnut of the chin and auriculars and a black throat spot. The breast and throat feathers are streaked, and they have a conspicuous crescent on the forehead.

The first nuptial plumage is acquired by wear. The adult winter plumage is acquired by a complete postnuptial molt in the winter quarters, as was the first winter plumage. This plumage is also similar to the first winter plumage, and the sexes are similar.

Since the cliff swallow is closely associated with other swallows it is not surprising that occasionally hybrids appear, although it is truly remarkable that hybridism occurs here in birds not only of different species but also of different genera. Mearns (1902) describes a hybrid between a barn swallow and a cliff swallow taken June 14, 1893, at Fort Hancock, Tex. He found a pair of swallows that were mated and had almost completed a nest attached to a rafter of a barn; the nest was similar to that of the barn swallow, having the entrance at the top. Both birds were shot; the male was a typical barn swallow, but the female, which was about to lay eggs, was a hybrid between the barn and cliff swallows. The characters were intermediate between those of the two species. Arthur H. Norton informs me that he observed a hybrid between the barn and cliff swallow in a colony near Portland, Maine, in 1883.

Chapman (1902) describes a very interesting male hybrid between the cliff and tree swallows taken by Leon C. Ilolcomb at Springfield, Mass., on August 20, 1902. It was a bird of the year, and in addition to presenting hybridism it also exhibited albinistic characters, though Chapman states this may have been the result of hybridity. In general this hybrid resembled the tree swallow below and the cliff swallow above, the rusty and buff markings of the cliff swallow, however, being in this supposed hybrid white. Chapman gives a complete comparative description of normal adults and hybrid and then comments as follows:

It is of course well known that in the Tree Swallow both birds of the year and adults moult before leaving us for the South while the Cliff Swallow migrates before moulting. It is consequently of interest to observe that in this hybrid moult has begun normally with the Innermost primaries.

This fact is also of importance in determining the bird’s age and, In connection with the unworn condition of the wing-feathers, it leaves no doubt that the specimen is in post-natal plumage.

The radical differences in the character of the nests of the supposed parents of this bird lead one to speculate on the type of nest-structure in which It was reared, but, unfortunately, our curiosity in this direction cannot be gratified.

Food: Beal (1918) has reported on the examination of the stomach contents of 375 swallows taken in every month from March to September. The food consisted almost entirely of animal matter; the small amount of vegetable matter (0.66 percent) was taken accidentally with food. However, two stomachs of birds taken in May in Texas were entirely filled with the fruit of Juniperus mon.osperrna, which was undoubtedly taken intentionally as food.

The animal food consists of insects with a few spiders. The insects consisted of beetles (26.88 percent), and of these members of the May-beetle family, chiefly the small dung beetles, which are easily taken on the wing as they fly in swarms near the ground, are important. Snout beetles or weevils, including the destructive cotton-boll weevil, were taken every month in large quantities, but in September weevils constituted 50 percent of the food. Thirty-five cliff swallows collected in the vicinity of cotton fields in Texas contained 687 boll weevils, an average of 19 to each stomach. Besides those mentioned above Beal found many other beetles, representing 118 species, in the stomach contents of the 375 cliff swallows. McAtee (1926) found the chestnut, chinquapin, and acorn weevils of the genus Balanimus and also Ops pinus, a special enemy of the white pine, during his special studies of the relation of birds to woodlots in New York State.

Beal found that ants, mostly winged forms, were eaten every month except March. Other Ilymenoptera eaten were wild bees and wasps and some parasitic species. The remains of 35 honeybees (Apis mellif era) were identified in 13 stomachs.

Hemiptera comprised 26.23 percent of the food, the most important representative being the well-known and harmful chinch bug (Blissus leucopterus).

Diptera comprised 13.95 percent. Green flesh flie3 were present in large numbers, but crane flies, which are eaten by other swallows. were not found in the stomachs of the cliff swallows.

Lepidoptera were not important; very few birds are fond of adult butterflies or moths though they may relish their larvae. Orthoptera, according to Beal, are lightly regarded by the cliff swallow, but Bryant (1914) includes the cliff swallows as destroyers of grasshoppers in California. He reports that an individual cliff swallow eats on the average of three grasshoppers a day. Beal found a few other insects, such as dragonflies, Mayflies, and lacewinged flies, represented in the food. McAtee reports that 18 specimens of the southern corn rootworm (Diabrotica duodecitnpunctata) in the stomach of a single cliff swallow. Murie (1935) examined a cliff swallow killed by an automobile; it had its crop filled with brine flies (EpA ydra mi2lbrae). The cliff swallow is one of the birds responsible for the destruction of mosquitoes.

It is evident from the above determinations that the cliff swallow is distinctly beneficial to the best interests of man as far as its food habits are concerned. It is also obvious from the nature of the insects eaten that the cliff swallows capture the greater part of their food during flight.

Beal (1901′) in a special investigation conducted in California identified the food of 22 nestlings varying in age from two days to those just leaving the nest. They were taken from May 30 to July 2, inclusive. Beal found animal matter in the food of the young to be similar to that eaten by the adults but differing in its relative proportions. Soft-bodied insects, such as Hymenoptera and Diptera, ranked highest, amounting to three-fourths of the food eaten by the young. Hemiptera and Coleoptera, hard-bodied insects, which are freely eaten by the adults, represented a relatively small percentage of the food of the young. An unaccountable difference existed in the fact that a considerable amount of gravel was taken from the stomachs of the young, while none was found in the stomachs of the adult cliff swallows examined.

Brown (1910) made observations of the feeding activities at colonies of cliff swallows in Washington County, Maine. He counted the number of visits of the adults and, finding that they carried on an average of three insects each trip, estimated that 900 insects were destroyed on an average for each day the young were in the nests. Such figures should convey a distinct meaning to those who may be ignorant of or doubt the value of the cliff swallow in its relations to the farmer on whose buildings it seeks a nesting site.

Voice: The swallows are not distinguished as far as their songs are concerned, and in this the cliff swallow is no exception. Roberts (1932) states: “The notes consist of a rapid twittering or chattering, sometimes rather harsh and creaky, but during the nesting-season these acquire a more musical quality and fill the place of a more pretentious nuptial song.” In Baird, Brewer, and Ridgway (1905) the song is described as “an unmusical creak, rather than a twitter, frequent rather than loud, and occasionally harsh, yet so earnest and genial in its expression that in effect is far from being unpleasant.” In an unpublished manuscript S. S. Dickey states: “These sounds are less pronounced and are evener in their outflow than are the sharper ones of the barn swallow. There is not so much metallic ‘squeak’ in their quality as that of the tree swallow.”

Enemies: The most serious enemy of the cliff swallow, especially of those nesting on barns and other buildings, is the English sparrow. The ousting of cliff swallows from their nests by English sparrows and their importance as a factor in the local fluctuations of the number of these swallows have been a subject of comment by scores of observers of which the following are typical:

Brewster (1906) states “the Eave Swallow suffers directly and very seriously from the encroachments of the House Sparrows who destroy its eggs and young and take possession of its nests whenever opportunity offers.” Barrows writes as follows: “About the larger cities and towns in Michigan the English Sparrow has been a potent factor in reducing the numbers of Cliff Swallows. The mud nests of swallows form convenient receptacles for the eggs of Sparrows and they often take possession of the nests and drive the swallows away entirely.” Forbush (1929) writes: “Thus the ‘Cliff’ Swallows under man’s protection became ‘Eaves’ Swallows and waxed fat and numerous until the decade beginning in 1870, when the House Sparrow began to increase and spread over New England. Then the nests built by the industrious Cliff Swallows were appropriated, after a struggle, by the swarming and ubiquitous Sparrows, whose clumsy and bustling occupancy soon resulted in the destruction of their stolen domiciles. As the Sparrows increased in southern New England, they spread northward and eastward until the greater part of the Cliff Swallows had been driven into Maine.” In Maine, where I have had an opportunity to observe many nesting colonies, there has been but little evidence of the molestation by English sparrows. It is becoming more and more apparent that, as the English sparrow population decreases, the cliff swallows are again becoming established where formerly they were ousted by the marauders. In the far West the English sparrow still remains a menace of increasing importance.

Grinnell (1937) gives a very interesting account of the invasion of the English sparrows into a large colony of cliff swallows that built their nests on the concrete walls of the Life Sciences Building at Berkeley, Calif. This building, completed in 1929 was first occupied by cliff swallows in 1935. This colony was closely observed by Grinnell and others, who reported on its progress from time to time. In 1936 the sparrows arrived and Grinnell’s comments are as follows:

On May 27, I first became aware of the presence of English Sparrows (Passer domesticus). At the southeast corner of the building I saw males of this aggressive species behaving as if evicting cliff swallows from the latter’s nests. Male sparrows, calling loudly, were either perched on the coping under the nests or were actually ensconced within the entrances of the swallows’ nests. Furthermore, on the southeast steps at 1 p. m. of May 27, I found remains of eggs. On May 30, at 1 p. in., in the same location, I saw on. the steps two dead young swallows of about hatching age, a splashed, incubated egg, and many fragments of eggshells: the latter definitely of the swallows because of the u~nber spotting on the shell fragments. Directly above, along the row of 48 swallows’ nests, were several male English Sparrows. * When I made a census of swallows’ nests on June 4, I counted 11 English Sparrows, 7 of which were males perched on the coping near swallows’ nests from which protruded wisps of nesting material; the birds were singing, if English Sparrows can be said to sing, as though sitting females were inside certain of the nests. Again and again, a sparrow was seen to enter a swallow’s nest; but I did not see a swallow and a sparrow enter the same nest. On the southeast steps, I saw more, dead, naked, seemingly just hatched swallows, and also two more splashed eggs. The same sort of observations were made on June 5 and 6. On the latter date, sparrows were Seen carrying nesting material into swallow’s nests at the southwest corner of LSB, so that all of the three corners of the building patronized by the swallows had also attracted sparrows. * * * I was amazed at the aggregate large numbers of English Sparrows around LSB, where before 1936 I could not recall ever having seen any, since its construction, in the summer time. Again we have illustrated how the fortunes of ~ne kind of animal may be influenced favorably by some circumstance in the economy of another. The swallows, by furnishing appropriate nest sites, brought the sparrows into a territory new for them. Partial supplantation, or succession, was in evidence.

Dayton Stoner (1939b) cites an interesting case, which he terms parasitism, in which English sparrows confiscated the nest of a cliff swallow and later were driven away or abandoned it after the female sparrow had deposited an egg. Three eggs of the cliff swallow were added. The sparrow egg hatched first, followed several days later by the hatching of the swallow eggs. The young swallows perished, but the young sparrow thrived through the diligent carp of the foster parents, the cliff swallows.

Friedmann (1931) writes as follows concerning the parasitism by the cowbird: “Mr. J. Hooper Bowles informs me that he has a parasitized set of four eggs of the Swallow and one of the Cowbird from La Anna, Pennsylvania, June 30, 1914, and that three nests of this Swallow [Cliff Swallow] at that place contained Cowbird’s eggs.”

Cliff swallows, which nest in situations well above level ground, would not be expected to be molested by snakes, but nevertheless cases on record indicate that snakes may sometimes prove to be a menace to nesting birds. Sawyer (1907) reports that an adder was discovered under the eaves of a barn where it was observed to be busily engaged in devouring cliff swallow eggs, and Cameron (1908) writes that a rattlesnake climbed the veranda poles of the Cross S ranch on Mispah Creek and devoured all the nestlings in reach.

Ants have proved very destructive to cliff swallows and other forms of life at San Diego, Calif. According to Anthony (1923) a colony of cliff swallows that had nested in one of the towers at the San Diego Museum was destroyed by the so-called Argentine ant introduced presumably from South America. Twenty-five dead nestlings were found in the deserted nests examined. The young were covered with the ants, while a steady column of the insects marched from the top of the tower to the ground.

The cliff swallowsï are more or less infested with Mallophaga and other external parasites, but so far as I know no comprehensive study has been made of the parasites and diseases of the cliff swallow. Knight (1908) states the nests often contain bird lice, ticks, and bed bugs. Several observers have reported finding bed bugs in the nests of cliff swallows. Cameron (1908) states that in Montana the ranch owners destroy cliff swallows because their presence brings bed bugs into the houses. Thus indirectly through man bed bugs become destructive to the best interests of the cliff swallow. According to some observers the prejudice against the cliff swallow in certain sections of the Middle West is so great that these birds may have to return to their primitive nesting sites on cliffs if they are to be perpetuated. Such an attitude toward a very beneficial species of bird is unfortunate and unwarranted. (See Widmann, 1907, p. 201.)

Predaceous birds cannot be considered as serious enemies of the cliff swallow. Indeed there are instances where the cliff swallows have nested in apparent harmony with prairie falcons and duck hawks. The appearance of a hawk in the vicinity of a colony of cliff swallows never creates any evidence of excitement, whereas other passerine birds may exhibit great concern.

Unseasonable weather, especially sudden drops in temperature after the swallows have arrived in spring, have sometimes proved destructive. Audubon (1831), writing concerning cliff swallows observed at Henderson on the Ohio River in the spring of 1815 states: “It was an excessively cold morning, and nearly all were killed by the severity of the weather.” Kimball (1889) made an investigation of the mortality of cliff swallows in June 1889 at Rockford, Ill., after it was discovered that very few of the birds were in evidence although they had come in their usual numbers earlier in the season. He says:

An examination of the newly completed nests revealed dead birds in nearly every nest. Large numbers were also found dead on the ground in the vicinity of the buildings frequented by them. Twenty-two nests were examined on one barn, about six miles northeast of this city, and thirty-seven dead birds were found in the nests. About two miles from this barn one hundred nests were examined on a large barn and dead birds were found, one or more in each nest. Five or six miles northwest of the city a like condition of affairs was reported. An investigation in a section of country six or eight miles north and fifteen to twenty miles south of the city revealed a similar destruction of Eave Swallows; the ground about the barn on one farm was reported “covered with dead birds.”

Mr. Kimball attributes this great mortality to the unusual weather conditions prevailing in that section of the country. There was a week of warm weather at the time the swallows arrived, followed by a prolonged cold period. The warm weather probably brought the birds north in advance of their usual time. Kimball estimates that in the northern section of Illinois over 90 percent of the swallows died.

From the foregoing and other similar reports it is evident that unseasonable cold weather may prove most disastrous to the cliffswallow population. In addition to the cold to which the swallows are subjected and to which they are not adapted they also suffer privation from the lack at such times of their all essential food, flying insects.

Fall: After the nesting season the adults and offspring of a colony cling together for some time as a group. It is then that their presence becomes conspicuous and attracts attention even from the casual observer, who is impressed by their great numbers as they congregate on telephone wires, buildings, or treetops. It is a common experience when traveling along the New England highways late in July or early in August to encounter many groups ranging in size from a few dozen to 75 or 100 birds. Later the colony groups join with others of the same and other species of swallows to roost in favo’rable traditional places creating large concentrations numbering many hundreds and even thousands of individuals.

Jackson (1923) saw 300 cliff swallows at Bent’s Camp, Mamie Lake, Wis., from August 23 to 28, 1917. On August 29 there were 40, and by August 31 there were only six left. Frances Schneider (1922) saw 1,000 cliff swallows congregated near a ranch reservoir near Artesia, Calif., on July 26, 1922. She noted another assemblage at the same place numbering several hundreds on July 29. According to A. S. Allen (1921) enormous numbers of cliff and other swallows assemble each year in the Suisun Marshes, Calif., after the middle of July. Cooke (1888) reported “thousands and thousands” of cliff swallows resting in the latter part of July on a marsh near Red Rock, Indian Territory (Oklahoma). Widmann (1907) writes: “The only time the species is present in great numbers is from the middle of August to the middle of September. At this period of southward migration thousands and thousands gather at night at the common roosts in the Spartina marshes of north Missouri. Mi are gone beLore the end of September.”

Such flocks as mentioned above do not migrate en mass but travel in relatively small groups. Cooke (1914) made extensive observations of the migration of cliff swallows at Caddo, Okia., late in August and early in September when swallows were in sight almost continuously moving southward. Late in August the flight of swallows began about at 5: 30 A. M. and lasted an hour. On September 1 the first group passed at 5: 10 and the last at 6:10. At 8 A. M. on September 25 about 30 cliff swallows passed in one flock going rapidly south; and for the next two weeks cliff swallows were seen about one-half of the evenings and one-third of t.he mornings in numbers from five birds to 200, about nine-tenths of them heading straight south and the rest flying about in search of food. The last cliff swallow was seen on October 9.

Range: North and South America.

Breeding range: The breeding range of the cliff swallow extends north to Alaska (Holy Cross, Rampart, and Bettles); northern Mackenzie (Rat River, Fort Goodhope, Lockhart River, Kendall River, and Artillery Lake); northern Manitoba (Cochrane River and possibly rarely Churchill); northern Ontario (Martin Falls and Moose Factory); Quebec (Godbout, Mont Louis River, Perc~, and the Magdalen Islands); and Nova Scotia (Baddeck). The eastern limits extend south along the Atlantic coast from Nova Scotia (Baddeck, Halifax, and Barrington) to Virginia (Aylett). South to central Virginia (Aylett, Lexington, and Blacksburg); northern Alabama (Fort Deposit) ; southern Texas (Corpus Christi and Fort Brown); Puebla (Atlixco); Jalisco (La Barca); Durango (Rio Sestin) ; and northern Baja California (San Quintin). The western limits extend north along the Pacific coast from northern Baja California (San Quintin and San Isidro), to Alaska (Mount McKinley, Flat, and Holy Cross).

Winter range: The winter range is imperfectly known but available information indicates that it extends from southern Brazil (Itarare) and northern Argentina (Tucuman) south to central Argentina (Cape San Antonio, Flores, and Zelaya).

The range as outlined is for the species of which three subspecies are currently recognized. The typical form, the northern cliff swallow (Petrockelidon aThifron~ ~~if~~),is the race breeding in Canada, on the west coast of Mexico, and in the United States south to Arizona, New Mexico, and Texas; the lesser cliff swallow (P. a. tachina) breeds in southern Texas and eastern Mexico; the Mexican cliff swallow (P. a. melanogaster) occupies the Mexican tableland north to southern Arizona and New Mexico.

Spring migration: Early dates of spring arrival in the United States and Canada are: Florida: Coconut Grove, March 4. Georgia~: Macon, April 11. District of Columbia: Washington, April 10. Pennsylvania: Coatesville, April 17. New York: Geneva, April 15. Connecticut: Hartford, April 17. Massachusetts: Boston, April 19. Vermont: Bennington, April 13. Maine: Ellsworth, April 21. New Brunswick: Grand Manan, April 14. Quebec: Montreal, April 19. Kentucky: Bowling Green, April 2. Missouri: St. Louis, April 10. Illinois: Chicago, April 11. Indiana: Bloomington, April 12. Ohio: Columbus, April 14. Michigan: Ann Arbor, April 11. Ontario: London, April 19. Iowa: Davenport, April 7. Wisconsin: Milwaukee, April 7. Minnesota: Minneapolis, April 13. Manitoba: Aweme, April 28. Texas: Kerrville, April 4. Kansas: Manhattan, April 13. Nebraska: Red Cloud, April 23. South Dakota: Yankton, April 21. North Dakota: Larimore, April 30. Saskatchewan: Indian Head, May 6. New Mexico: State College, April 4. Arizona: Tucson, April 5. Colorado: Loveland, April 24. Wyoming: Wheatland, May 1. Montana: Big Sandy, May 2. Alberta: Banif, May 8. Mackenzie-Peace River, May 20. California: Los Angeles, February 26. Ore. gon: Narrows, March 11. Washington: Tacoma, April 4. British Columbia: Okanagan Landing, April 19. Alaska: Nulato, May 10. Fall migration: Late dates of fall departure are: Alaska: Ramparts of Porcupine River, August 28. British Columbia: Okanagan Landing, September 15. Washington: Seattle, October 9. Oregon: Kiamath County, September 18. California: Kernville, October 28. Mackenzie: Pelican Rapid, August 24. Alberta: B anif, September 3. Montana: Fortine, September 8. Wyoming: Yellowstone Park, September 6. Colorado: Denver, October 3. Arizona: Salt River Bird Reservation, October 14. New Mexico: junction of Beaver Creek and the Gila River, October 16. Saskatchewan: Eastend, September 6. South Dakota: Sioux Falls, September 10. Nebraska-Valentine, October 4. Kansas: Onaga, October 8. Texas-Austin, October 1. Manitoba: Aweme, September 24. Minnesota: Jackson County, October 8. Wisconsin: Madison, October 4. lowa: Giard, September 30. Ontario-Ottawa, September 30. Michigan: Sault Ste. Marie, September 27. Ohio: Youngstown, September 27. liiinois: Rantoul, September 19. Missouri: Concordia, October (3. Tennessee: Athens, September 26. Mississippi: Biloxi, October 23. Prince Edward Island: North River, September 4. New Brunswick: St. John, September 9. Maine: Phillips, September 9. Vermont: Wells River, September 15. Massachusetts: Woods Hole, September 28. Pennsylvania: State College, October 3. District of Columbia: Washington, September 7. North Carolina: Lake Eden, September 12. Alabama: Booth, September 20. Florida: St. Augustine, November 11; Key West, November 27. One banded (34: 95949) at Dell Rapids, S. Dak., on June 14, 1937, was recaptured at Ghent, W. Va., on July 16, 1937.

Casual records: A specimen was taken by a native on St. Paul Island, Alaska, about June 10, 1918.

Egg dates: Arizona: 8 records, June 3 to August 10. California: 109 records, April 27 to July 5; 55 records, May 8 to June 20, indicating the height of the season. Illinois: 16 records, May 20 to July 5; 8 records, May 22 to June 20. Massachusetts: 13 records, May 30 to June 20; 7 records, June 2 to 11. Pennsylvania: 10 records, May 31 to June 17. Texas: 60 records, April 15 to July 19; 30 records, May 6 to June 12.


Dr. H. C. Oberholser (1903), in naming this swallow, describes it as similar to the northern cliff swallow but “decidedly smaller, the forehead ochraceous instead of cream color.” He says further that it “is intermediate between lunifron8 [~albifrons] and melanoga8tra, approaching in size very close to the latter. In respect to the color of the forehead, as well, it.s aberration from lu~ifrons is in the direction of melanogastra, with which also it may be found to intergrade. After due allowance has been made for individual variation which, however, does not exist to an unusual degree, the characters exhibited by this new race seem to be very constant, at least in the considerable series available for examination.”

The “considerable series” he refers to seems to have consisted of 7 specimens of tachina and 8 of meZaiwgastra, not a very impressive number. Mr. Ridgway (1904) recognized both forms on what was practically the same series, with one more tachi’na and two more melanogaster (==me7anogastra). These two forms are practically alike in size, the only conspicuous difference being in the color of the forehead. Mr. Ridgway calls this “fawn color, dull cinnamon, or wood brown” in tao/tine, and “chestnut or cinnamon-rufous” in melanogaster.

The breeding range given for tao/dna, in the 1931 Check-list, is “western Texas, the Rio Grande Valley, and through eastern Mexico to Vera Crux.”

The general habits of the lesser cliff swallow apparently do not differ materially from those of the northern cliff swallow, except that it seems more inclined to nest under primitive conditions, on cliffs and canyon walls, and less inclined to nest on buildings than the northern bird.

The eggs of the lesser cliff swallow are similar to the eggs of the other cliff swallows. The measurements of 58 eggs, reported by Col. John E. Thayer (1915), average 20.2 by 13.7 millimeters; the eggs showing the four extremes measure 23.1 by 14.5, 20.7 by 14.8, and 17.5 by 13.0 millimeters.


The Mexican cliff swallow is readily separable from the northern cliff swallow by its smaller size and by its “chestnut” or “cinnamonrufous” forehead and rump; but it is v#~ry similar to the lesser cliff swallow in size, and the latter is intermediate between the other two races in the color of the forehead. The breeding range of the Mexican cliff swallow extends from southern Arizona and southwestern New Mexico southward over the Mexican tableland to Guatemala.

Nesting: While I was collecting with Frank C. Willard along the San Pedro River in the vicinity of Fairbanks, Ark., we visited the home ranch of the Boquillas Cattle Co. to hunt for swallows’ nests in their large 2-story barn. We found a small colony of barn swallows nesting on the joist braces over the carriageway in the lower story. In the empty hayloft above a few Mexican cliff swallows were flying in and out of the building, just beginning to construct their mud nests on the rafters in the peak of the roof. At that date, May 17, 1922, there were no completed nests of the cliff swallows, and most of the barn swallows’ nests held ihcomplete sets. Mr. Willard investigated this colony later, of which he (1923a) says: “On June 9, in company with Mr. Ed. C. Jacot, I again visited the colony and found that it consisted of eight pairs. The birds looked out at us from each of the six completed nests. Two nests were placed at the peak of the roof by each of three adjacent pairs of rafters. Two incomplete nests were farther down the line. Four of the nests held complete sets, two of four and two of five eggs. Incubation was barely noticeable.”

In the same paper Mr. Willard tells of finding, in August 1915, a somewhat numerous colony of these swallows at Fort Huachuca, Ariz., “nesting in scattered locations all over the fort.” Eight pairs had nests “under the eaves of the railroad station and of the section foreman’s house.” One nest was “under the roof of the open coal storage shed.” Several nests were found in second-story rooms of unfinished buildings. He estimated that there were about 25 pairs in the entire cokny.

With the exception of the pairs nesting in the new quarters, all the nests were attached to well painted woodwork. In the quarters, they were attached to the plastered walls close up against the ceilings. They were the usual gourd-shaped nests of mud pellets, with a few hits of grass for lining and a very few feathers. In the dry atmosphere of the mountains, the pellets of mud dried very quickly and It was surprising to see how fast a pair of birds could build up the walls of their abode. Both birds took part In the building. On arriving at the nest with a pellet of wet mud, the bird would press It into its appointed place and hold It there for several seconds until It was “set.” I never saw a pellet thus held In place drop off when the bird loosened Its hold.

Mrs. Bailey (1928) mentions several large nesting colonies in New Mexico on information furnished by J. S. Ligon; these colonies were located in the more primitive fashion, on cliffs along the banks of flyers; the smallest colony contained 60 occupied nests, another was occupied by 100 pairs, another “colony was composed of about four hundred and fifty occupied nests extending for a distance of a hundred feet,” and in the largest group there were about 500.

Eggs: The four or five eggs that usually comprise the full set for this swallow show all the variations seen in eggs of the species elsewhere. These are fully described under the northern cliff swallow. The measurements of 30 eggs average 19.8 by 14.1 millimeters; the eggs showing the four extremes measure 21.8 by 14.0, 21.5 by 15.0, and 18.1 by 13.4 millimeters.

In all other respects the habits of the Mexican cliff swallow do not seem to differ materially from those of the northern subspecies.

About the Author

Sam Crowe

Sam is the founder of He has been birding for over 30 years and has a world list of over 2000 species. He has served as treasurer of the Texas Ornithological Society, Sanctuary Chair of Dallas Audubon, Editor of the Cornell Lab of Ornithology's "All About Birds" web site and as a contributing editor for Birding Business magazine. Many of his photographs and videos can be found on the site.

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