The shape is similar to a swallow, but the swift is slightly larger than European swallows. The wings are long compared to the body and their crescent shape is easily seen in gliding flight. The tail is relatively short and forked. Males and females cannot be distinguished externally. The plumage is sooty to brownish black except for the greyish-white throat patch, which is, however, difficult to see in flight. The face, seen from the front, appears roundish; the eyes are relatively large and the iris is deep brown. The small, black beak is slightly curved downwards. The short feet are blackish flesh-coloured. The four toes end in sharp talons; as in all swifts, they are all pointed forward.
Adult swifts weight about 40 grams on average, but the weight varies quite a bit with nutritional status. Non-breeders and swifts that have just arrived at the breeding site are usually somewhat heavier than breeding birds. The trunk length averages 17 cm, and when the wings are put on they cross and overhang the tail by about four cm. The wingspan is between 40 and 44 cm. Compared to other bird species, the primaries are very elongated; the upper and lower arms are short and compact.
The juvenile plumage is darker and less shiny, the white of the throat is more extensive and purer than in adult birds. In addition, young birds are distinguished from adults by the white feather seams, which are most conspicuous on the axillary feathers, the wing coverts, the large plumage and especially on the forehead. Only the fringes of the forehead feathers remain until the juvenile moult, while the other white fringes disappear quite soon due to wear. One-year-olds look like adult swifts; they are best recognised by the worn juvenile plumage, in which the ends of the tail feathers are more rounded.
In Central Europe, the swift mainly breeds on multi-floor old buildings, including residential houses, church towers, factory buildings or railway stations. On such buildings, many cavities on roofs and façades are used, such as eaves or roller shutter boxes. New buildings with a dense outer skin offer hardly any breeding opportunities. Due to the availability of suitable breeding sites, swifts often settle in only a few places, such as town centres, industrial or harbour facilities, and in small towns often exclusively on churches or other historic buildings.
Swifts were originally predominantly rock-breeders, but today they are rare in Central Europe and only known from a few regions, such as the Elbe Sandstone Mountains. It is assumed that the transition from rock-breeding to building-breeding took place in the Middle Ages. Possibly, castles built of rough natural stone were the link through which the birds approached human buildings and became a synanthropic bird.
The text is a translation of an excerpt from Wikipedia (https://de.wikipedia.org/wiki/Mauersegler). On wikipedia the text is available under a „Creative Commons Attribution/Share Alike“ licence. Status: 14 December 2021