[order] Apodiformes | [family] Apodidae | [latin] Tachymarptis apus | [UK] Swift | [FR] Martinet noir | [DE] Mauersegler | [ES] Vencejo Común | [IT] Rondone eurasiatico | [NL] Gierzwaluw

Gierzwaluw determination

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Common swifts are 16-17 cm in length with a wingspan of 42-48 cm, depending upon the age of the individual. Common swifts are black-brown in color with the exception of a white to cream colored chin and throat (located directly underneath the beak). In addition, the topside of the flight feathers is a paler brown-black color in comparison to the rest of the body. Apus apus can also be distinguished by its moderately forked tail feathers, its narrow, sickle-shaped wings, as well as its shrill, screaming call. Apus apus is frequently mistaken for a swallow or a hummingbird. Apus apus is larger and has very a different wing shape and flight pattern than do hummingbirds or swallows. All members of the family Apodidae possess a unique morphological characteristic, a lateral "grasping foot" in which toes one and two are opposed by toes three and four. This allows the common swift to occupy areas such as walls of rock, chimneys, and other vertical surfaces that would be difficult for other types of birds to inhabit. Apus apus is a sexually monomorphic species, meaning that the males and females look alike. There has been no seasonal or geographical variation reported in the appearance. However, it is possible to distinguish juveniles from adults in the slight difference in richness and uniformity of their coloration, as it is common for juveniles to be blacker in color, as well as to have a pale forehead, white-fringed feathers, and a starker white patch under the beak. This distinction is best observed at close range.
Apus apus is a highly gregarious species. Common swifts typically nest, roost, migrate, and hunt for food in groups throughout the year. In addition, they are unique in their ability to stay aloft for extended periods of time. It is not uncommon for these swifts to spend the entire day on the wing, only landing to feed young or to roost at night. It is estimated that common swifts fly at least 560 miles per day during the nesting season, illustrating their endurance and strength, as well tremendous aerial ability. They can also mate and forage for food while in the air. Common swifts typically fly in lower airspace when the weather is poor (cold, windy, and/or wet), and will move to higher airspaces when the weather is more favorable for extended aerial activity.

The majority of the breeding habitat of A. apus is located in temperate zones, where there are suitable trees for nesting and sufficient open spaces in which to fly to gather food. The habitat of Apus apus during the months following migration into Africa, however, is tropical. Common swifts have been observed breeding from sea level to several thousand meters in elevation. Apus apus prefers areas with trees, or buildings with open spaces, and is able to use vertical surfaces such as rock walls and chimneys for nesting due to a unique physical adaptation possessed by all swifts

Apus apus is a widespread summer visitor to most of Europe, which accounts for less than half of its global breeding range. Its European breeding population is very large (>6,900,000 pairs), and was stable between 1970-1990. Although there were declines in a number of countries during 1990-2000, these were set against stable or increasing trends elsewhere in Europe - notably in the sizeable populations in France, Italy and Turkey-and the species probably remained stable overall.

Common swifts are insectivorous, feeding solely on aerial insects and spiders that it gathers in its mouth as it glides through the air. The insects are gathered together inside the throat through the use of a product from the salivary glands, to form a food-ball or bolus. Apus apus is commonly attracted to swarms of insects, as it aides in the ease of collecting sufficient food. It has been estimated that there are an average of 300 insects per bolus, and that each nest of young may receive 3000 food-balls per day. These numbers may vary based upon the abundance of prey. Among some of the most commonly consumed insects are wasps, bees, and ants, beetles, and flies.

This species has a large range, with an estimated global Extent of Occurrence of 10,000,000 km². It has a large global population, including an estimated 14,000,000-34,000,000 individuals in Europe (BirdLife International in prep.). Global population trends have not been quantified; there is evidence of a population decline, but the species is not believed to approach the thresholds for the population decline criterion of the IUCN Red List (i.e. declining more than 30% in ten years or three generations). For these reasons, the species is evaluated as Least Concern. [conservation status from birdlife.org]

Apus apus usually first breeds at two years of age, but the age of the first breeding can vary based upon the availability of nesting sites. The common swift is a monogamous species, meaning that it typically has one partner in a lifetime, and that the bond between the pair is maintained from year to year. The male A. apus typically chooses the nest site. Upon the arrival of the female shortly thereafter (usually within a period of days), the nesting site is protected by the pair. The nest is typically composed of grass, leaves, hay, straw, and flower petals (among other things). The nesting site usually includes the nest itself and the areas directly surrounding the nest. Courtship, some copulation, and the rearing of the chicks all occur at this site. Colonies of A. apus typically include 30-40 nest sites, reflecting the gregarious nature of the common swift mating system. Apus apus is more likely to fight to defend a nesting site than it is to defend a mate. Males attract their female partners through attainment of a good nesting site prior to their meeting. Upon their first meeting it is not unusual for the initial responses of the potential mates, both male and female, to be hostile. If interested and unpaired, the female will enter the nest site tentatively, thereby inviting her potential partner to stroke her chin with its bill. If this encounter is successful, the female may also invite her potential partner to allopreen. Allopreening is the process by which birds smooth or clean each others feathers with their beak or bill. This mutual action begins the pair-bonding process.
Common swifts typically breed from late April to early May through mid-September when the young are fledged. One of the most unique characteristics of A. apus is its ability to mate while in flight, although they also can mate while perched. Mating occurs every few days following the arrival of suitable weather, until a few days after the young have fledged. Following a successful copulation, anywhere from one to four white eggs may be laid, however a clutch size of two is most common. Eggs must then be dutifully incubated for 19-20 days while the embryos develop. Both parents participate in the incubation of the clutch. After the young hatch, it can take an additional 27-45 days before fledging occurs.
Both parents take turns incubating the clutch following fertilization and prior to hatching. For the duration of the first week following hatching, the clutch is typically brooded all day long. During the second week, the young are brooded for approximately half of the day. For the remainder of the time, until the clutch is fledged, they are rarely brooded during the day, but are almost always covered at night. Both parents participate equally in all aspects of the raising of the young. In the event that unusually bad weather persists or food sources become scarce during the time shortly after the hatching of the young, the young possess the ability to become semi-torpid, a hibernation-like state, thereby reducing the energy demands of their rapidly growing bodies. This adaptation allows young A. apus to survive with little food for 10-15 days. During the time from hatching until fledging, the young are fed almost exclusively in the nest. The young are fed food-balls consisting of insects gathered by the parents during flight and held together with a salivary gland product, creating the food bolus. While the young are smaller, they will share a food bolus among them. However, once young are larger they become able to swallow an entire food bolus on their own.

Migration to Africa on a broad front south through Europe, but ringing recoveries indicate that birdsmove primarily south to south-west in autumn (Glutz & Bauer 1980), with a more easterly trend on the return movement suggested (Cramp 1985). This theory is supported by Fry et al. (1988), stating that the species is commonest in Senegambia in autumn, but from Mali eastwards to Nigeria it is commonest in spring. However, sometimes recorded in vast numbers from Liberia in spring (Gatter 1997). An absence of West African ringing recoveries suggests a diagonal movement across the Sahara by birds moving through western Europe to NW Arica. Pekinensis moves south through E Africa via the Middle East (and the southern coast of the Red Sea in particular). Although not averse to sea crossings the relative scarcity of migrant records in Libya and abundance in NW and NE Africa are significant. Winters primarily south of the equator with the western nominate race found primarily from Zaire and Tanzania in the north to Zimbabwe and Mozambique in the south. Pekinensis winters primarily in Namibia and Botswana Complex intra-African movements occur, and are believed to be mainly weather-provoked in attempts to avoid rainfall. These movements could account for winter records away from main wintering grounds e.g. West Africa. Nominate birds leave S Africa generally by late January or early February and pekinensis leaves by early March. Arrival in the Western Palearctic occurs in strength from mid-March in the northern Mediterranean with arrivals further north continuing until early June. Autumn migration from Europe occurs from late July (late individuals can be seen in November, rarely) with arrival in wintering grounds from September. Main spring and autumn passage, Egypt, late March to mid-May and mid-August to mid-October; records late January to early February could indicate local wintering or early migration (Goodman & Meininger 1989). Autumn movement over W Turkish migration watch-points peaks from mid-late August (Porter 1983). Southward passage through Israel mid-May to mid-November, with spring migration between mid-January to mid-June, peaking April-May: in spring pekinensis moves mainly in March-April, whilst in autumn this race occurs primarily in E, whilst the nominate form occurs throughout the country (Shirihai 1996). Winters in small numbers north of Sahara: on Cape Verde Is, with records between August-June (Hazevoet 1995), possibly in Egypt amongst flocks of Pallid Swifts along the Nile (Short & Horne 1981), Israel (Shirihai 1996) and in the Arab Gulf states (Bundy & Warr 1980). Small numbers winter, perhaps only irregularly, in N Africa, Arabia and N India. Ali & Ripley (1970) state that those birds wintering in India are pekinensis. 200 Common Swifts flying N of Deothang, Bhutan, April 1996 (c. 1,065m) (Robson 1996). First for Hong Kong, April 1997 (Robson 1997). Has been recorded, and no doubt could be recorded, anywhere south and west of the breeding range. Accidential records from Spitsbergen, Iceland, Faroes, Azores, Seychelles, Assumption Island, Aldabra Islandand , most spectacularly, from Bermuda, where a single was recorded in November 1986. Eleven recorded Seychelles up to December 1995 during September-December and March (Skerret 1996). (Chantler Phil Griessens G 2000)