Vaux’s Swift

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 Vaux’s Swift – the common name and sub-species reflect the nomenclature in use at the time the description was written.

This, the smallest of the North American swifts, replaces in the northwestern part of our continent the common chimney swift of the eastern States. It breeds from southeastern Alaska and central British Columbia southward to the Santa Crus Mountains of California and eastward to Montana and Nevada; but it is rare east of the Cascades and the Sierra Nevada.

Throughout most of its range it is much less numerous than the chimney swift is in the East. Most observers speak of it as rare during the breeding season, but S. F. Rathbun tells me that in the vicinity of Seattle, Wash., “the little Vaux’s swift is more or less a common bird. It arrives late in April and, though widely distributed, is more apt to be seen in the river valleys, somewhat open, in which are tall, dead trees; and quite likely one reason for this is that among such trees are some that are hollow and will afford nesting places for the birds.”

Spring: While migrating, or when preparing to migrate, this little swift often gathers into immense flocks. The following observation by H. H. Sheldon (1922b), made at Santa Barbara, Calif., illustrates this point: “On April 29, 1922, about I r. M., the largest flock of Vaux Swift (Chaetura vauxi) I have ever seen or, in fact, heard of, circled over my house several times. By careful estimate I judged the number to be very nearly six hundred individuals. My observations of the Vaux Swift have heretofore been made only within its breeding range; while this is my first observation of a migrating flock, such an immense gathering of this rather rare wilderness dweller is no doubt a most unusual occurrence.”

Courtship: Mr. Rathbun writes to me: “This swift does not appear to be mated when it comes, but after a short time some change is noted in its actions. As they fly about, suddenly with a shrill twitter one of the swifts makes a dash or a dive at another, and away both rush, each striving to out-fly or out-dodge the other, the chase brought to an end only when one escapes, or, as often is the case, both fly off in company. As it appears to be quite playful, these actions may be partly in sport, though at this particular time some must have an earnest intent, for the courtship of this little swift evidently takes place upon the wing.”

Nesting: He says in his notes: “It begins to nest quite soon after it has mated. Its nest is built inside a hollow tree, as in this respect the bird chiefly follows the ancient habit of its kind. But with the arrival of man changes have taken place in some of the primitive sections where this swift is found, and it seems to have begun to adapt itself to these, for on occasions it is known to build a nest in some disused chimney, a practice of its eastern relative, the chimney swift, which so commonly uses a like place in which to nest.

“The nest of Vaux’s swift is a small, rather saucer-shaped affair. It is attached to the inner wall of a hollow tree, or on rare occasions in a chimney, and usually some distance from the top. It is made of small pieces of twigs stuck together with a gluey saliva of the bird, the twigs broken off from the tips of dead limbs of trees by the swift as in flight it passes the branches. It does not seem to be quickly made, as shown by an instance when we found a pair of these birds nesting in a chimney. A few years ago, on a day in early June, we went to a little schoolhouse near the Snoqualmie River in the foothills of the Cascade Mountains, to find out whether the chimney of the building was in use as a nesting place by Vaux’s swift. This was about 40 miles east of Seattle. When we reached the spot no swifts were to be seen, but after a wait of a half hour or so a pair of the swifts appeared and flew in circles about the chimney. Without warning one of the birds dived into it so quickly the eye could scarcely follow it. After a brief stay within the swift came out of the chimney and was joined by its mate, and for a short time both flew around in the vicinity, then ascended very high to mingle with some swallows. Nearly an hour elapsed before one of the swifts returned. It circled the chimney several times, then dropped into it so quickly as to resemble a dark streak. This time it remained in the chimney at least ten minutes. After another long wait both of the swifts returned, one entered the chimney, and several minutes elapsed before it came out. From these actions we assumed that the one that went into the chimney was making a nest, and invariably each time it flew out it gave a sharp twitter. For some time thereafter we stayed in this locality, but although a number of these swifts were seen none entered the chimney.

“Eleven days later we once more visited the schoolhouse. It was about 10 o’clock in the morning when we reached the place, but no swifts were in the locality. After a short time a pair of the birds arrived, both circled the top of the chimney six times, and then one entered by a straight-down dive. The other, which had remained outside, flew away but returned five minutes later and twittered. Immediately the swift in the chimney came out, and in company both left the vicinity. Forty-five minutes elapsed before the pair came back. With rapid twittering notes they swiftly circled the chimney a number of times, then flew from sight. We went on the roof of the building and looked down the mouth of the chimney but could see no sign of any nest. Next we entered the school house and, as the large stovepipe hole in the side of the chimney was high above the floor, we stood upon a table, stuck our head through the hole, and carefully looked at the inside of the chimney. A good sight of its upper part was had because of the light, but its lower part was dim, and no nest could be seen. Then we went to the lower part of the building into which the chimney extended to the ground, and by the removal of a few loose bricks from one of its sides we had a good view of the lower part of the inside of the chimney. Here we found the nest. It was about 5 feet from the bottom of the chimney and firmly attached to the wall in the angle of the southeast corner, which might give some protection from the rain, as usually this comes with a wind from some point south. The nest was a small, slightly shallow structure, compact and well made, but it contained no eggs. We left the locality soon after but returned later in the day, and during our brief stay one of the swifts came back and went into the chimney.

“A few days later we again went to the schoolhouse to see if any eggs were in the swift’s nest In this we were disappointed, for since our preceding visit the building had become occupied by a family who, of course, made use of the chimney for its ordinary purposes; for, while we were there, smoke issued from it, and evidently the swifts had deserted their nest as it still lacked eggs. We remained some long time in the vicinity of the schoolhouse, but no signs of any swifts were seen at all.”

D. E. Brown writes to me that “on July 8, 1924, a nest was found in an old chimney near Seattle that contained young birds. I could not tell whether there were four or five young birds. On June 30, 1925, a nest with four eggs was found in an unused chimney of a fireplace in Seattle. The nest was 6 feet from the bottom of the fireplace, and the female bird was on the nest. The eggs were slightly incubated at this date.”

Although there are other records of nesting in chimneys, the great majority of Vaux’s swifts apparently still cling to the ancestral habit of nesting in hollow trees. The trees chosen are usually tall, dead stubs, frequently charred by forest fires and often hollow nearly or quite down to the ground level, and the nest is generally well down from the top, or even near the ground level. W. L. Dawson (1923) says: “Almost invariably the birds nest within twenty inches or such a matter of the bottom of the cavity, no matter how elevated the orifice. * * * The Vans Swift also nests, according to Mr. C. Irvin Clay, of Eureka, in the stumps of logged-off redwood lands. The birds enter by weather fissures, and since the stumps are almost always undermined by fire, it sometimes happens that the nest is found beneath the level of the ground.”

There are four nests of this swift in the Thayer collection in Cambridge, all from Eureka, Calif. One nest is made of pine needles, glued together, and was fastened to the inner wall of a hollow stub and only 2 feet above the ground level. Another was made of spruce twigs and needles and was placed in a burnt redwood stub, 20 feet high; the nest was 12 feet down from the top on the inside. Three of these nests are very small and narrow, so that the eggs had to be laid in two parallel rows; and the bird must have incubated lengthwise of the nest, for two of the nests held six eggs each, one five and one four. One larger, well-made nest was constructed of spruce and fir twigs and was profusely lined with spruce and fir needles, smoothly laid; this nest was 3 feet from the ground inside a hollow redwood stub 18 feet high. The other nest was taken from a redwood stub 60 feet high and about 10 feet in diameter at the base; it was burned black on the outside, but the inside was smooth and unburned; a V-shaped break on one side afforded an entrance to the hollow 20 feet below the top of the stub; the cavity below this opening was 14 feet deep, and the nest was placed only 8 inches from the bottom of the cavity.

Some unusual nesting sites have been reported. Charles A. Allen (1880), of Nicasio, Calif., writes: “They are to be found only on the highest hills or mountains, where there are plenty of pines. In these trees they construct their nests, which they build in old holes excavated by the California Woodpecker. They invariably select old, decayed trees, and build at great heights, so that it is impossible to get their eggs.” As Mr. Allen evidently did not actually see a nest in such a situation, his statement is subject to confirmation and is offered here only as a suggestion.

J. A. Munro (1918) says: “Mr. T. L. Thacker sent me a nestling in the flesh, from Yale, B. C. It had fallen from a nest that was built under the roof of the C. P. R. water tank. There are a number of small openings under the eaves, and Mr. Thacker tells me that several pairs breed there every year.”

William L. Finley (1924) tells of a still more remarkable nesting site: “At Wiedemann Brothers’ nursery, is an engine house with a metal smokestack sixty feet tall and thirty inches in diameter. The lower end of the flue broadens out and opens into the front of the boiler. A pair of Vaux Swifts dropped down the metal flue sixty-two feet and built their nest on the front of this metal boiler. * * *

“Mr. Wiedemann did not find the nest until he heard squeakings in the boiler and thought some bats had taken possession. Opening the metal doors of the boiler, there he saw the parent Vaux Swift with her four young birds. He saw her go and come and even caught her, but she did not object, for when she flew out of the door she was soon back through the top of the stack with more food.”

Eggs: Vaux’s swift lays three to six eggs; four, five, and six seem to be the commonest numbers. The eggs are usually elliptical-ovate or elongate-ovate, rarely ovate. They are pure dead white, without gloss, or sometimes faintly creamy white in color. The measurements of 51 eggs average 18.5 by 12.4 millimeters; the eggs showing the four extremes measure 19.8 by 12.2, 18.5 by 13.5, 16.8 by 12.0, and 18.8 by 11.8 millimeters.

Young: Mr. Finley (1924) watched the feeding of the young swifts in the nest described above, of which he writes:

I stood outside at twelve o’clock, noon, and saw one of the parent Swifts come flitting along just above the chimney top, suddenly swerve and drop In. He, or she, whichever It was, was feeding every fifteen or twenty minutes. I went below and with the aid of an electric light, I could see the bird feed her young. Sometimes she would light on one side of the nest and sometimes on the other, to feed. Once I saw her clutch the edge of the nest and brace herself with her tall underneath, and she jabbed her bill In the mouth of a young bird and fed by regurgitation. As she started up the long climb, she quivered her wings, hooked her sharp toes In the sooty side of the stack and walked right up as If she were going up a ladder.

William B. Davis (1937) made some observations on a nest located in a brick chimney, and about 12 inches below the roof of the building, in Bellingham, Wash.; on August 2, between 9: 37 and 11: 15 a. in., the parent, or parents, made eight trips to the nest to feed the young. He writes:

When I first looked Into the chimney, I was greeted by the clamor of the young. Their calls consisted of series of rasping notes uttered In rapid succession. The young were perched on the edge of the nest, each with Its posterior end projecting over the edge and with Its head directed toward the corner of the chimney. Below the nest the chimney was streaked with excrement, a circumstance which indicated the young were not defecating in the nest. This probably explains the clean condition in which Edson found the empty nest when It was collected two days later. No evidence was obtained that the parent bird removed the fecal sacks of the young, although one can infer that it probably did when the young were smaller and unable to perch on the edge of the nest. Each time the parent returned from a trip afield, the young became vociferous, their calls lasting until the old bird left. By listening for the calls of the young, one could mark the coming and going of the adult.

After the parent had returned from its sixth trip, I moved close to the chimney and witnessed the feeding of the young. When first observed, the old bird was clinging to the chimney beside the nest, supported partly by the stiff tail feathers. The young were facing her (2), each with its mouth wide open clamoring for food and vying with Its nest mates. I was led to wonder what relation existed between lustiness of voice and the chance of being fed at that particular visit. Later, after additional observations, I learned that proximity to the parent determined to a large extent which of the young was fed. At succeeding visits, the old bird alighted first at one side of the nest and then at the other, feeding the one, or ones, closest. The food, consisting of Insects, largely leaf hoppers (as determined by gullet examination of the young), was placed far back in the open mouth of each young one. * * ï After the parent bird had fed one of the young, It caught sight of me and dropped to a lower level in the chimney where it alighted out of sight I moved closer and placed my bead directly over the opening to get a better view. As I did so, I heard the rapid beating of wings and, thinking the bird was coming out, I instinctively jerked my bead to one side to avoid being hit. It did not appear, so I looked in a second time and again I beard wing beats. This time I kept my position, and after my eyes had become adjusted to the darkness, I observed Its stunt several times. The bird would let go its hold on the wall, and, by rapidly heating its wings, suspend Itself in the middle of the chimney and at the same time produce the br-r-r-r-ing sound. Apparently the sound was produced by the beating of the wings themselves, for I could not observe them touching the sides of the chimney. During these performances the young were quiet. I interpreted this behavior as a means employed to Intimidate the intruder, much as does the hissing of the chickadee or the swooping dive of the Red-tailed Hawk.

Plumages: As far as I can learn from the rather scanty material examined, the sequence of plumages and molts in Vaux’s swift is about the same as in the closely related eastern chimney swift. The spiny quills of the nestling develop into a juvenal, or first winter, plumage that is much like that of the adult. The narrow whitish edgings on the scapulars of the young bird soon wear away; and adults will average paler on the throat and under parts.

I have seen adults molting the contour feathers and primaries in August, but the molt of the primaries must be very gradual in a bird that spends so much of its life on the wing. Mr. Rathbun tells me that this swift has a complete molt during summer.

Food: Almost nothing has been published on the food of Vaux’s swift, beyond the statement by Mr. Davis (1937) that the food fed to the young consisted of insects, largely leafhoppers. Probably its food consists wholly of small flying insects, such as mosquitoes, gnats, various flies, and perhaps small beetles. On dull, damp days much of its food is gathered at low levels, but on clear hot days, when the insects fly high, it ascends to great heights in pursuit. I can find no record of stomach contents.

Behavior: Mr. Rathbun says in his notes that “Vaux’s swift flies at all heights, at times just above the surface of the ground, and again it will be seen high against the sky. Its flight need not be mistaken for any swallow. It is fast, lacks a certain smoothness, and is apt to fly more directly, circle less; also, it has at times somewhat of a darting movement, erratic as it were, which brings to mind the actions of a bat. In fact, this bird is always in a hurry.”

Ralph Hoffmann (1927) notes a marked difference in flight between this swift and the swallows: “A close observation of the tail shows that it never displays a forked tip; it either ends in a point like a cigar or is spread like a fan when the bird makes a sudden turn. * * * The Swift takes a number of very rapid strokes, its wings fairly twinkling through the air, and then sails with the long narrow wings curved backward and slightly downward.”

Vaux’s swift shares with its eastern relative the social habit of roosting in chinmeys in large numbers at certain seasons. Mr. Rathbun has described this very well in the following elaborate notes: “About the middle of August the actions of this swift show the time is near when it intends to leave the region for its winter home. Now the social trait of this bird is much in evidence. For late in each day the swifts begin to assemble in the vicinity of some hollow tree of size, or some good-sized chimney not in use, within which they aim to pass the night. We have watched this action on the part of the birds from its commencement to the close. In one case where a large, tall chimney was used, 25 days elapsed from the time when first they began to use it until the last of the swifts ceased to do so. The swifts began to resort to the chimney about the middle of August, and each evening thereafter for the next 10 days showed an increase in their number until at least 500 made use of it. Then for 16 days the number of birds steadily grew less until only three swifts entered the chimney to pass the night, and after this for several days no more were seen to use the place.

“The swifts began to come to the locality where the chimney stood an hour or two before sunset. Usually they flew about the chimney or quite close to it. From time to time there were arrivals, which mingled with those in flight, all forming a long and narrow flock of flying swifts that swept around the top of the chimney, their twittering so loud and ceaseless as to be heard some distance. At times a few would leave the flock and enter the chimney, but the constant arrival of others seemed to keep the flock entire. As they circled some made feints to enter, and this appeared to be a sign that soon an entrance would be made by all. Usually these actions lasted for more than half an hour, but ceased when the twilight reached a certain stage. For then the swifts would suddenly enter their retreat, and while this act was taking place, it bore a likeness to a long black rope one end of which dangled in the chimney’s mouth.

“Each evening the performance was much the same, but sometimes an incident would be connected with it. Once when the swifts were racing, a pigeon hawk appeared and dashed at them. Instantly the birds scattered, with the hawk in chase of one it had singled from the flock, but as it made no capture it returned and perched for a short time in a tree not far distant from the chimney. But when it left the swifts at once returned in close formation, hung above the chimney for an instant, and then appeared to fall therein. Not one wavered in the act, all seemed to have a single aim: to get inside the chimney just as quickly as they could.

“But this we noticed: that the temperature and the amount of light prevailing each evening influenced the swifts as to the time they would enter the chinmey. On the cooler and darker ones the entrance would be made much earlier, whereas on the warmer and fairer evenings they would enter it quite late.”

Dr. S. A. Watson (1933) made the following observation on another method of roosting at Whittier, Calif., during the spring migration:

On the evening of May 12, 1933, large numbers of Vaux Swifts (Chaetura vaazi) were noticed circling around the barns of Mr. John Gregg near Whittier. As night came on they began flying Into a hay loft where they would cling to the walls and to each other. At places they would cover large sections of the wall five or six deep. It was estimated that at least three thousand swifts found shelter in the barn that night.

Next morning the birds began leaving the barn at about eight o’clock. They would fly out, a few at a time, circle around a while and then fly off in groups. They returned again the next two nights in about the same numbers, and for the two nights following these the numbers decreased rapidly, and on the sixth night they failed to return. The birds were heavily parasitized with lice and seemed weak and emaciated. A dozen or more were found dead each morning during the period they were taking refuge in the barn.

Since there was considerable snow In the mountains when the swifts were staying over, it is assumed that the unfavorable weather barrier caused them to accumulate here until warmer days and better feeding conditions called them farther north.

Voice: Mr. Rathbun tells me that “its note is a rapid twitter, given often as it dashes through the air with other swifts and sometimes with the swallows, for it is a bird fond of company, though at times only one or two are seen.” Charles A. Mien (1880) says that the note is different from that of the chimney swift: “They do not utter the sharp, rattling chipper of that species, but have a weak, lisping note, which is, as near as I can imitate it, chip-chip-chip-cheweetcheweet, and this is only to be heard during the pairing season, when two, probably the male and female, are chasing each other.” Mr. Hoffmann (1927) says: “On the breeding ground pairs of Vaux Swifts pursue each other with a faint chip-chip-chip.”

Field marks: Vaux’s swift looks and acts like a small chimney swift. It might be mistaken at a distance for the black swift, but it is much smaller and much lighter in coloration below. It can be easily distinguished from the white-throated swift, as it lacks the conspicuous white areas on the breast and the flanks. Its flight, as described above, is different from either of the other western swifts.

Fall: Mr. Rathbun’s notes from the vicinity of Seattle, Wash., containing the following observations on the migration through that State: “Throughout the first three weeks in September we have observed Vaux’s swift to pass by in its flight toward the south. The birds will be seen at intervals all day and at times even at twilight. They fly at all heights, singly or in groups, and as a rule quite rapidly. It is not uncommon to see them in the company of other birds: black swifts, nighthawks, and certain of the swallows, species that are on the wing southward at the same time. Even when migrating the playfulness of this little swift is seen, for often one will pursue another of its kind. And on occasions we have seen it make a dash at a black swift, or a nighthawk, though when this took place no notice was taken of the act by either of these birds.

“On one occasion in fall we observed a large number of Vaux’s swifts in flight whose actions were quite different. It was at the west coast of this State, along the ocean beach. When first seen, the swifts were ‘milling’ in the air within a narrow limit, the sight bearing a resemblance to a swarm of bees about a hive. Again and again this action was repeated. At times the birds would suddenly scatter as if a wind had strewn them, but soon they reunited and once more began to mill, though meanwhile the flock slowly drifted southward and at last was lost to view. On this occasion in company with the Vaux’s were a number of the black swifts. These were at some height above the smaller swifts, and their graceful circling flight was in marked contrast to that of the Vaux Winter: The winter range of Vaux’s swift is imperfectly known but is supposed to be in Central America. An important addition to our knowledge has been recently made by George H. Lowery, Jr., who found this swift wintering on the campus of the Louisiana State University, East Baton Rouge Parish, La. He has kindly lent me his unpublished manuscript on the subject, from which I quote as follows:

“Swifts were first observed in Louisiana outside of the regular seasons of occurrence during the winter of 1937.-, when two individuals were recorded almost daily from November through February. One of them was captured and banded on February 16, 1938.

“During November 1938 swifts were again noted in the same chimney on the university campus. This time a larger number, 5 to 10, were found. They were observed almost daily from November through February. Six specimens were caught, five of which were banded and released; the sixth was prepared as a study skin. Only after king placed alongside specimens of C. pelagica in the Museum of Zoology collection was it noted that the bird differed from that species. Being smaller and paler, it was immediately suspected of being C. vauxi. The question arose as to whether the five birds banded and released were the same species as the one made into a skin. These were recaptured on February 15, along with four additional unbanded birds, and all proved to be of the smaller and paler variety. The four unbanded birds were retained as museum specimens, and the others were released.

“After careful comparison with material kindly lent by the Museum of Vertebrate Zoology of the University of California and by the Bureau of Biological Survey, it is obvious that the five specimens taken at Louisiana State University in February belong to Chaetura vauxi. Both Dr. H. C. Oberholser and George Willett have examined the specimens and confirmed this identification. It is therefore probable that the specimen captured and released in February 1938 was also of this species.”

DISTRIBUTION
Range: Western North America.

Breeding range: The breeding range of Vaux’s swift extends north to southeastern Alaska (probably Baranof Island and probably Thomas Bay); and northern British Columbia (probably Flood Glacier and probably Telegraph Creek). East to British Columbia (probably Telegraph Creek, Hazelton, Lac Ia Hache, Vernon, Edgewood, and Newgate); western Montana (probably Glacier National Park, probably Kalispell, and Red Lodge); west-central Oregon (Fort Klamath and Mount McLoughton); and eastern California (Meadow Valley, probably Camphells Hot Springs, and probably Kenawyers). South to central California (probably Kenawyers, and Santa Cruz). West to the coastal regions of California (Santa Cruz, San Rafael, Sebastopol, and Eureka); Oregon (Tillamook and Beaverton); Washington (Tacoma, Seattle, Crescent Lake, and Bellingham); British Columbia (Chilliwack, Comox, and Courtenay); and southeastern Alaska (Chickamin River and probably Baranof Island).

Winter range: Imperfectly known. At this season the species has been detected north to East Baton Rouge Parish, La. (see above), Taxco, State of Guerrero, and Leguna del Rosario, State of Tlaxcala, Mexico; and south to San Lucas and Mazatenango, Guatemala.

Spring migration: Early dates of spring arrival are: Arizona: Chiricahua Mountains, April 13; Agua Caliente, April 22. California: Eureka, April 10; Buena Park, April 14; Redwood City, April 16; Azusa, April 23. Oregon: Mercer, April 29; Beaverton, April 30; Fort Klamath, May 6. Washington: Nisqually, April 11; Tacoma, April 23; Clallam Bay, May 3. Idaho: Coeur d’Alene, May 6; Rose Lake, May 11. British Columbia: Chilliwack, April 26; Arrow Lakes, April 28; Revelstoke, May 12.

Fall migration: Late dates of fall departure are: Alaska: Cascade Bay, September 9. British Columbia: Kispiox Valley, September 3; Errington, September 15; Okanagan Landing, September 15. Idaho: Priest River, September 10; Trestle Creek, September 11. Washington: Mount Rainier National Park, September 16; Seattle, September 25; Tacoma, October 1. California: Nicasio, September 24; Buena Park, September 24; Santa Cruz, October 5; Los Angeles, October 14. Arizona: Tombstone, September 20; Pima Indian Reservation, September 26; Santa Catalina Mountains, October 6.

Casual records: Two individuals were recorded in Jasper National Park, Alberta, on July 6, 1918. The British Museum (Natural History) has two specimens taken in Costa Rica, one at Los Cuadros de Laguna, in July 1898, and the other at Carrillo on November 7, 1898. This institution also lists a specimen from Honduras without exact locality or date of collection, but it seems probable that all three of these examples may be referable to the form resident in southern Central America.

Egg dates: California: 44 records, May 7 to July 9; 22 records, June 12 to 30, indicating the height of the season.