Barn swallow (Hirundo rustica)

Dec 04, 2016 Features / Columnists, Interesting Creatures in Guyana

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The barn swallow (Hirundo rustica) is the most widespread species of swallow in the world. It is a distinctive passerine bird with blue upperparts, a long, deeply forked tail and curved, pointed wings. It is found in Europe,

Asia, Africa and the Americas. In Anglophone Europe it is just called the swallow; in Northern Europe it is the only common species called a “swallow” rather than a “martin”.
There are six subspecies of barn swallow, which breed across the Northern Hemisphere. Four are strongly migratory, and their wintering grounds cover much of the Southern Hemisphere as far south as central Argentina, the Cape Province of South Africa, and northern Australia. Its huge range means that the barn swallow is not endangered, although there may be local population declines due to specific threats.
The barn swallow is a bird of open country that normally uses man-made structures to breed and consequently has spread with human expansion. It builds a cup nest from mud pellets in barns or similar structures and feeds on insects caught in flight. This species lives in close association with humans, and its insect-eating habits mean that it is tolerated by man; this acceptance was reinforced in the past by superstitions regarding the bird and its nest. There are frequent cultural references to the barn swallow in literary and religious works due to both its living in close proximity to humans and its annual migration. The barn swallow is the national bird of Austria and Estonia.
The adult male barn swallow of the nominate subspecies H. r. rustica is 17–19 cm (6.7–7.5 in) long including 2–7 cm (0.79–2.76 in) of elongated outer tail feathers. It has a wingspan of 32–34.5 cm (12.6–13.6 in) and weighs 16–22 g (0.56–0.78 oz). It has steel blue upperparts and a rufous forehead, chin and throat, which are separated from the off-white underparts by a broad dark blue breast band. The outer tail feathers are elongated, giving the distinctive deeply forked “swallow tail”. There is a line of white spots across the outer end of the upper tail.
The female is similar in appearance to the male, but the tail streamers are shorter, the blue of the upperparts and breast band is less glossy, and the underparts paler. The juvenile is browner and has a paler rufous face and whiter underparts. It also lacks the long tail streamers of the adult.
The song of the barn swallow is a cheerful warble, often ending with su-seer with the second note higher than the first but falling in pitch. Calls include witt or witt-witt and a loud splee-plink when excited (or trying to chase intruders away from the nest). The alarm calls include a sharp siflitt for predators like cats and a flitt-flitt for birds of prey like the hobby.
The barn swallow typically feeds 7–8 m (23–26 ft) above shallow water or the ground, often following animals, humans or farm machinery to catch disturbed insects, but it will occasionally pick prey items from the water surface, walls and plants. In the breeding areas, large flies make up around 70 percent of the diet, with aphids also a significant component. However, in Europe, the barn swallow consumes fewer aphids than the house or sand martins.
The barn swallow drinks by skimming low over lakes or rivers and scooping up water with its open mouth. This bird bathes in a similar fashion, dipping into the water for an instant while in flight.
Swallows gather in communal roosts after breeding, sometimes thousands strong. Reed beds are regularly favoured, with the birds swirling en masse before swooping low over the reeds. Reed beds are an important source of food prior to and whilst on migration; although the barn swallow is a diurnal migrant that can feed on the wing whilst it travels low over ground or water, the reed beds enable fat deposits to be established or replenished.
The male barn swallow returns to the breeding grounds before the females and selects a nest site, which is then advertised to females with a circling flight and song. The breeding success of the male is related to the length of the tail streamers, with longer streamers being more attractive to the female. Males with longer tail feathers are generally longer-lived and more disease resistant, females thus gaining an indirect fitness benefit from this form of selection, since longer tail feathers indicate a genetically stronger individual which will produce offspring with enhanced vitality.
Males with long streamers also have larger white tail spots, and since feather-eating bird lice prefer white feathers, large white tail spots without parasite damage again demonstrate breeding quality; there is a positive association between spot size and the number of offspring produced each season.
Both sexes defend the nest, but the male is particularly aggressive and territorial. Once established, pairs stay together to breed for life, but extra-pair copulation is common, making this species genetically monogamous despite being socially polygamous. Males guard females actively to avoid being cuckolded. Males may use deceptive alarm calls to disrupt extra pair copulation attempts toward their mates.
As its name implies, the barn swallow typically nests inside accessible buildings such as barns and stables, or under bridges and wharves. The neat cup-shaped nest is placed on a beam or against a suitable vertical projection. It is constructed by both sexes, although more often by the female, with mud pellets collected in their beaks and lined with grasses, feathers, algae or other soft materials. Barn swallows may nest colonially where sufficient high-quality nest sites are available, and within a colony, each pair defends a territory around the nest which, for the European subspecies, is 4 to 8 m2 (43 to 86 sq ft) in size. (Source: Wikipedia)

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