# The Zoologist/4th series, vol 5 (1901)/issue 722/On the Breeding Habits of the Swift in Derbyshire, Jourdain

Published in The Zoologist, 4th series, vol 5, issue 722 (August, 1901), p. 286–289
ON THE BREEDING HABITS OF THE SWIFT IN DERBYSHIRE.
By the Rev. F.C.R. Jourdain, M.A., M.B.O.U.
Although a widely distributed bird, Cypselus apus is difficult to observe at nesting-time, on account of the inaccessibleness of its usual breeding-places. Presumably this is the reason for the uncertainty which exists with regard to one or two points in its history.
The Swift is one of the most regular of our migratory birds, and is usually first seen in this county between May 2nd and 5th. Mr. Storrs Fox has seen one at Bakewell as early as May 1st, but May 4th may be taken as the average date, and it is not at all uncommon for them to arrive exactly on that day. Although they resort to the nest-holes before that time, eggs are seldom found before the last days of May, and about the same numbers seem to return every year. Most nests in this neighbourhood are made under the eaves of lofty buildings or in thatch, but some pairs may be found nesting in the natural crevices of the steep limestone rocks at Dovedale and other places. The Swift can squeeze itself through a remarkably shallow opening, barely wide enough to admit the fingers, and the nests are usually some little way from the entrance. Where suitable sites are available, they seem to prefer to breed in company, but a single pair may often be found nesting at some distance from any colony. For over thirty years a colony of seven to eight pairs has nested under the eaves of a house in this neighbourhood, which stands by itself on a hillside, and offers unusual facilities for observation.
The first thing that strikes one in watching these Swifts is that they play a regular game. On a summer's evening some five or six birds may be in sight, hawking busily in different directions, when suddenly one will dash off towards the house screaming. Every Swift in sight at once joins in the chase, ​and the flock race round and round the house, invariably in one direction, passing close to where the nests are, and screaming all the time. The sitting birds squeal in sympathy as the flock dashes past, and, after several complete circuits, the squealing ceases, the flock suddenly disperses, and desultory hawking is resumed, until the signal is again given, and another game is started. Occasionally one sees short chases carried on in the open, but the recognized course is round the house, and the game is repeated time after time on a fine evening. When the birds are laying the eggs often roll out of the nest, especially when Starlings and Sparrows dispute the possession of the holes, and fragments of broken eggs are usually to be found underneath the breeding-place of a colony.
With regard to the number of eggs laid by each hen, there is some difference of opinion. The point is one worth investigation, especially as it has an important bearing upon the question as to the position of the Cypselidæ. Mr. Howard Saunders, in the new edition of his 'Manual,' says:—"The eggs... are two in number, and when more are found in the same nest they may be the produce of two females." In the same strain. Dr. A.G. Butler writes:—"The number of eggs is normally two; four eggs have been found in one nest, but it has yet to be proved that they were the product of the same hen." On the other hand. Prof. Newton, and many other authors, give the number as two to three, and even four. Lord Lilford says "generally three," and Mr. O. Grabham (Zool. 1898, p. 352), who has found three eggs in Swifts' nests often, even in isolated nests, comes to the conclusion that "the evidence is strongly in favour of the hen-bird by no means infrequently laying three eggs." In some interesting notes on the Swift, by Mr. Steele-Elliott (Zool. 1900, p. 479), is an account of a nest which contained three eggs, and was only observed to be visited by one pair of birds. This is confirmed by a note (p. 556) from Mr. A. Bankes, who observed the same thing for two successive years.
In the colony at Ashburne, to which I have already referred, I have often found nests with three eggs, and on one occasion with four: but of course there was no proof that all the eggs were laid by the same bird, except perhaps the similarity of the eggs in each clutch to one another. This year, by first ​ascertaining the number of old birds, and afterwards carefully examining as many nests as possible, I have obtained the following results:—
Number of birds in colony, fourteen. Number of nests, seven (each with sitting bird on June 11th).
1st nest was built on the top of a Sparrow's nest, and contained two incubated eggs, while the remains of a third egg were lying on the ground below.
2nd nest.—Three eggs slightly incubated.
3rd nest.—Three eggs of a very elongated type about half-incubated.
4th nest.—Three eggs much incubated.
5th nest.—Two newly hatched young, and one egg chipping.
The 6th and 7th nests were inaccessible, but a bird was sitting in each.
After carefully marking the eggs from nests 2, 3, and 4, I found that it was quite easy to sort out the clutches without making use of the marks.
Now, even supposing that the hens in nests 6 and 7 were sitting hard on empty nests, and had deposited their two eggs in two other nests (a most improbable supposition), there still remain fifteen eggs as the produce of seven hens; so that at least one hen must have laid three eggs.
May we not reasonably infer that the Swift not infrequently lays three eggs, as its alpine relative (Cypselus melba) is known to do?
The nests which I have examined consisted of a mass of feathers, a few straws, bud-cases, and blossoms from trees, fastened together with shining glutinous matter into a saucer or shallow cup. In one case this cup was built on to the top of a Sparrow's nest, and another was placed by the side of a Sparrow's nest containing young.
Young Swifts are extraordinarily unlike their parents, but, as they have already been described by White of Selborne and others, it is hardly necessary to do so here. One striking characteristic, which is very noticeable in the embryo, is the large proportionate size of the tibia as compared with the adult. The tarsus and claws are also well developed, while the featherless wings seem very small in proportion to the body. As far as ​one could tell, the hind claw in the embryo was opposed to the rest, and not directed forward as in the adult.
When the young leave the nest one or two are generally killed by striking the walls of the house. Sometimes, but more rarely, an old Swift is picked up stunned, but usually recovers after a time. Starlings often take possession of Swifts' nesting-places, but not without having to fight for them, and sometimes Starling and Swift will come headlong to the ground, grappling one another, in which case the Swift generally gets the worst of it.
We do not often see Swifts after the third week in August, and, though an occasional straggler may sometimes be seen as late as Sept. 1st, it is quite exceptional, and for the next eight months their dark forms and cheerful screams are absent from our skies.
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