H
SWIFTS
that can be seen in Portugal
Alpine Swift
(Thachymarptis melba)
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Common Swift
(Apus apus)
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Plain Swift
(Apus unicolor)
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White-rumped Swift
(Apus caffer)
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Pallid Swift
(Apus pallidus)
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Little Swift
(Apus affinis)
Taxonomy, Ecology and Biology of Swifts
Evolution and systematics
Swifts are birds remarkably adapted to an aerial lifestyle, exhibiting unique morphological and metabolic adaptations such as energy-saving gliding flights, very long sickle-shaped wings and compact body. These characteristics allow them to fly almost continuously during the non-breeding period. These birds sleep, mate, feed, drink and collect materials to build their nest during flight. In the recent past, the taxonomic classification of these birds has undergone some changes. Currently, and according to the IOC (International Ornithological Committee), the taxonomic authority by which the andorin Project is governed, the swifts belong to the order Apodiformes. This new order was created based on molecular evidence. However, some taxonomic entities continue to consider these birds elements of the order Caprimulgiformes (frogmouths, nightjars and owlet-nightjars), mainly due to the type of feeding ecology, since both swifts and nightjars feed exclusively on insects that they hunt during flight.
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Topography
RESTRICES
The tail feathers, also called retrices, are attached to the caudal vertebra and their main function is flight, being used to glide, change direction or brake.
UPPER TAIL COVERTS
Feathers that protect the base of the tail feathers (retrices).
RUMP
It corresponds to the area below the back and up to the upper tail feathers. The rump is usually under the closed wings of a bird when perched.
BACK
Area between mantle and rump. The back is usually covered by the wings when the bird is perched.
MANTLE
Area below the back of the neck. Consisting of a distinct group of feathers that cover the upper part of the back, flanked by the scapular feathers.
NAPE
Area behind the neck.
THROAT
Area between chin and chest.
CHIN
This is a very small area located at the base of the lower jaw, at the top of the throat. Often, careful observation of the chin can be a good clue to identify certain species.
BILL
The swifts bill looks very small when closed, but is actually huge so these birds have the ability to catch insects in mid-flight.
Forehead
Area between beak and crown.
CROWN
Area referring to the top of the swifts head.
EAR COVERTS
Set of feathers that cover the ears.
TERTIALS
The three innermost feathers of the wing are called tertiary feathers and their main function is to protect the primary and secondary feathers from the sun when the bird is resting. As swifts hardly ever land, they have tiny tertiary.
SCAPULARS
Feathers covering the base of the wing. Scapulars flank the mantle and usually cover the curve of the wing.
LESSER COVERTS
Feathers close to the leading edge of the wing that overlap the bases of the median coverts.
WING EDGE COVERTS
Swifts are very fast and need extra protection for their wings. There are therefore very small feathers that protect the edge of the wing that are not found in most other species.
ALULAS
Three feathers that grow in the place corresponding to our thumbs.
MEDIAN COVERTS
Feathers that overlap the bases of the greater coverts.
PRIMARIES COVERTS
Feathers that overlap the bases of the primary feathers and have the function of protecting them.
GREATER COVERTS
Feathers that overlap the bases of the secondaries and whose main function is to protect them.
SECONDARIES
The inner feathers at the base of the wing are called secondary and their main function is to help the bird to glide during flight.
PRIMARIES
They are the longest feathers of the swifts and their main function is to give impulse to the flight. Unlike most feathers that grow under the skin of birds, primaries are attached to the wing bones.
PRIMARIES
They are the longest feathers of the swifts and their main function is to give impulse to the flight. Unlike most feathers that grow under the skin of birds, primaries are attached to the wing bones.
PRIMARIES COVERTS
Feathers that overlap the bases of the primary feathers and have the function of protecting them.
SECONDARIES
The inner feathers at the base of the wing are called secondaries and their main function is to help the bird to glide during flight.
GREATER COVERTS
Feathers that overlap the bases of the secondary ones and whose main function is to protect them.
MEDIAN COVERTS
Feathers that overlap the bases of the greater coverts.
Morphology
The swifts' pointed wings and compact body allow them to make fast flights with frequent direction changes, which facilitates the capture of insects. Although all swifts have sickle-shaped wings with 10 primaries (flight feathers), the structure of the tail is variable from species to species. While some are slightly rounded or square, others are strongly biforked; and some species use these feathers as support when clinging to vertical surfaces. Swifts have poorly developed, almost vestigial legs, which do not allow them to walk or perch on branches or electricity wires. However, they have developed strong, sharp claws well adapted to clinging to vertical surfaces. Swifts also show marked differences in size. Body length ranges from 9 to 25 cm, weight from 5 to 205 g and wingspan from 20 to 60 cm. Among the smallest swifts are the Pygmy Swiftlet (Collocalia troglodytes) and the Pygmy Palm Swift (Tachornis furcata); and among the largest are the White-naped Swift (Streptoprocne semicollaris) and the Alpine Swift (Tachymarptis melba). These Apodiformes generally have dark and opaque plumages with some white patches, however the Chestnut-collared Swift (Streptoprocne rutila) and the Tepui Swift (Streptoprocne phelpsi) have more colourful plumages and present a very characteristic reddish collar. The majority of swift species do not present sexual dimorphism, with no appreciable differences in plumage or size between the sexes. The swifts, despite having a small beak, have a large mouth that facilitates the capture of insects during flight.​​
Distribution
Swallows have wide distributions, occurring almost everywhere on the planet, with the exception of the Arctic tundra, Antarctica and some isolated oceanic islands. Some swallow species are endemic to certain regions. There are four endemic species in Australia, nine in North America and about 20 in Central and South America. Africa is not only the nesting ground for more than 30 species, but also hosts most of the species that nest on the European and Asian continents in winter.
Habitat
Swifts occur in a wide variety of habitats and are primarily dependent on food availability. These birds hunt the insects on which they feed over a wide range of habitats, from tropical and temperate rainforests, savannahs and deserts, to the temperate rainforests and coniferous forests of Scandinavia. Their nesting habitats, on the other hand, are more dependent on cliffs, escarpments, trees and human constructions.
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Behaviour
During the non-breeding season the swifts stay in the air and can spend several months without ever landing. In the nesting season, swifts spend the whole day in flight and only return to their nests to overnight and feed the offspring. These birds have wide feeding areas and on days of cold and rainy weather they can search for food more than 60 km away from their nesting site. The young, in the nest, are able to lower their body temperature and remain in torpor until the weather gets warmer and the adults return to the nest sites with food. Nesting strategies depend on the type and location of the nests. Some species, like the Lesser Swallow-tailed Swift (Panyptila cayennensis), build solitary nests in rock crevices or in large tree branches. Other species, such as the Edible-nest Swiftlet (Aerodramus fuciphagus), nest in high densities, where over 100,000 individuals may use a single cave system. Although they may occur in small groups, swifts are very sociable birds and it is common for them to gather in flocks of a few hundred individuals to feed or migrate. Among the unique aspects that characterise swifts, such as the ability to sleep and to mate in flight, the power of echolocation of some species of the genus Aerodramus also stands out. These birds emit pulses of sound that echo and use these echoes to find their nests and navigate inside the caves. However, as this echolocation is not very sensitive, the birds are not able to use this strategy to obtain food. The sound of their wings clipping the wind and the shrill vocalizations that some species produce denounce their presence. Another characteristic of this group of birds is their fidelity to nesting sites. In some cases, the nests are used year after year by the same pair, with only the addition of some new material. Swifts have a long lifespan and are generally monogamous. The life expectancy of some species can exceed 20 years and annual survival rates are over 80%.
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Feeding ecology and diet
Swifts are exclusively insectivorous birds and the type of insects consumed depends on the feeding location and weather conditions. On hot and dry days, these birds feed at higher altitudes and consume a greater number of prey, since there is greater availability of food. On cold and wet days, on the other hand, these birds feed at lower altitudes and near areas with high insect productivity, such as lakes and other water bodies. The food for the young is carried in the mouth of the parent and consolidated into a "pellet" with the addition of a sticky substance produced by the salivary glands. A single food pellet can contain 1500 insects belonging to 60 different species.
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Reproduction and life cycle
The nesting season for tropical species usually coincides with the peak of the wet season, during which there is greater availability of insects. On the other hand, for the swifts of temperate zones the nesting season begins with the longer and warmer days of late spring, so that the feeding of the young coincides with the peak of food availability. Thus, changes in climate can compromise the productivity of the species by causing a lag between the breeding season and the peak of maximum food availability. This lag can also put adults at risk, as they are dependent on a large amount of food to build up their fat reserves before long distance migrations. Swifts tend to be gregarious during the breeding season and some species nest in colonies. However, different species have different breeding habits. Species in the genus Hirundapus do not build a nest and lay their eggs directly in hollow tree holes. The African Palm Swift (Cypsiurus parvus) uses its adhesive saliva to stick its eggs to the vertical nests, incubating them in an upright position. The Horus Swift (Apus horus) takes over burrows built by European bee-eaters (Merops apiaster) or Sand Martins (Riparia riparia) to build its nest. The White-rumped Swift (Apus caffer) and the Bates’s Swift (Apus batesi) use old mud nests built by swallows and cover them with feathers. The most elaborate structures are the tubular nests of the Swallow-tailed Swifts (Panyptila sp.), which are made of plant fibres glued with saliva. Swifts of the genus Cypseloides use plant matter and mud to build their unique nests, which are located behind impressive waterfalls. The Edible-nest Swiftlet (Aerodramus fuciphagus) builds its nest using only the secretion produced by its salivary glands, and these nests are harvested and used to make "swallow's nest soup", a highly prized delicacy in China. Swifts may lay between 1 and 6 eggs and the incubation of the eggs is carried out by both sexes for 20 to 28 days, depending on the species. The development of the chicks is slow when compared to other birds of similar size, taking between 4 and 9 weeks.
DID YOU KNOW?
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Swifts spend most of their lives in flight!
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They don't land, not even to sleep! And they can spend several months flying non-stop!