Seychelles Swiftlet
Encyclopedia
The Seychelles Swiftlet (Aerodramus elaphrus) is a small bird
of the swift
family. It is found only in the Seychelles
Islands in the Indian Ocean
.
It is 10 to 12 cm long with a wingspan of 28 cm and a weight of about 10.7 grams. The upperparts are dark grey-brown and are slightly paler on the rump. The underparts are pale grey-brown, darkest on the undertail-coverts. The bill
and legs are black. The tail is dark and slightly forked. The wings are long and narrow but are less pointed than those of the other swift species which sometimes visit the islands.
A soft, twittering call is given in flight by feeding flocks and the birds also have a low-pitched, metallic clicking call used for echolocation
in cave
s.
The Seychelles Swiftlet is related to the smaller, paler Mascarene Swiftlet
(Aerodramus francicus) of Mauritius
and Réunion
and has been treated as a subspecies
of it in the past. The two are thought to have separated about 500,000 years ago.
The Seychelles Swiftlet breeds on the islands of Mahé
, Praslin
and La Digue
. It formerly bred on Félicité
and has been recorded as a non-breeding visitor on Aride
. It often feeds over freshwater and mountain passes but can be seen over most habitats. It feeds on flying insect
s, particularly ant
s.
Breeding takes place all year round at a small number of colonies
in caves. The nest
is bracket-shaped and made of strands of lichen
and casuarina
needles held together by saliva
. One white egg
is laid and is incubated
for about 25 to 30 days. The young birds are fed by both parents and fledge
after 42 days.
The species is classified as Vulnerable
by the IUCN due to its small population (2,500 to 3,000 birds) and limited number of breeding sites. Threats include disturbance, use of insecticide
s and predation by introduced Barn Owl
s and cat
s.
Bird
Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...
of the swift
Swift
The swifts are a family, Apodidae, of highly aerial birds. They are superficially similar to swallows, but are actually not closely related to passerine species at all; swifts are in the separate order Apodiformes, which they share with hummingbirds...
family. It is found only in the Seychelles
Seychelles
Seychelles , officially the Republic of Seychelles , is an island country spanning an archipelago of 115 islands in the Indian Ocean, some east of mainland Africa, northeast of the island of Madagascar....
Islands in the Indian Ocean
Indian Ocean
The Indian Ocean is the third largest of the world's oceanic divisions, covering approximately 20% of the water on the Earth's surface. It is bounded on the north by the Indian Subcontinent and Arabian Peninsula ; on the west by eastern Africa; on the east by Indochina, the Sunda Islands, and...
.
It is 10 to 12 cm long with a wingspan of 28 cm and a weight of about 10.7 grams. The upperparts are dark grey-brown and are slightly paler on the rump. The underparts are pale grey-brown, darkest on the undertail-coverts. The bill
Beak
The beak, bill or rostrum is an external anatomical structure of birds which is used for eating and for grooming, manipulating objects, killing prey, fighting, probing for food, courtship and feeding young...
and legs are black. The tail is dark and slightly forked. The wings are long and narrow but are less pointed than those of the other swift species which sometimes visit the islands.
A soft, twittering call is given in flight by feeding flocks and the birds also have a low-pitched, metallic clicking call used for echolocation
Animal echolocation
Echolocation, also called biosonar, is the biological sonar used by several kinds of animals.Echolocating animals emit calls out to the environment and listen to the echoes of those calls that return from various objects near them. They use these echoes to locate and identify the objects...
in cave
Cave
A cave or cavern is a natural underground space large enough for a human to enter. The term applies to natural cavities some part of which is in total darkness. The word cave also includes smaller spaces like rock shelters, sea caves, and grottos.Speleology is the science of exploration and study...
s.
The Seychelles Swiftlet is related to the smaller, paler Mascarene Swiftlet
Mascarene Swiftlet
The Mascarene Swiftlet is a species of swift in the Apodidae family.It is found in Mauritius and Réunion.Its natural habitats are subtropical or tropical moist lowland forests, subtropical or tropical high-altitude shrubland, subtropical or tropical high-altitude grassland, caves, arable land, and...
(Aerodramus francicus) of Mauritius
Mauritius
Mauritius , officially the Republic of Mauritius is an island nation off the southeast coast of the African continent in the southwest Indian Ocean, about east of Madagascar...
and Réunion
Réunion
Réunion is a French island with a population of about 800,000 located in the Indian Ocean, east of Madagascar, about south west of Mauritius, the nearest island.Administratively, Réunion is one of the overseas departments of France...
and has been treated as a subspecies
Subspecies
Subspecies in biological classification, is either a taxonomic rank subordinate to species, ora taxonomic unit in that rank . A subspecies cannot be recognized in isolation: a species will either be recognized as having no subspecies at all or two or more, never just one...
of it in the past. The two are thought to have separated about 500,000 years ago.
The Seychelles Swiftlet breeds on the islands of Mahé
Mahé, Seychelles
Mahé is the largest island of the Seychelles, lying in the north east of the nation. The population of Mahé is 80,000. It contains the capital city of Victoria and accommodates 90% of the country's total population...
, Praslin
Praslin
Praslin is the second largest island of the Seychelles, lying 44 km north east of Mahé. Praslin has a population of around 6,500 people and comprises two administrative districts; Baie Sainte Anne and Grand' Anse . The main settlements are the Baie Ste Anne, Anse Volbert and Grand' Anse.It was...
and La Digue
La Digue
La Digue is the fourth largest inhabited island of the Seychelles, lying east of Praslin and west of Felicite Island. It has a population of about 2,000 people, who mostly live in the west coast villages of La Passe and La Réunion. It has an area of 10 km²...
. It formerly bred on Félicité
Felicite Island
Félicité Island is a small heavy forested granitic island 4 km east of La Digue in the Seychelles. It is 2.68 km² and today is a resort that can handle up to 20 guests.The highest point on the island is 213 meters....
and has been recorded as a non-breeding visitor on Aride
Aride Island
Aride Island is the northernmost granitic island in the Seychelles and is 10 km north of Praslin. It is 68 hectares in area and is a nature reserve. Aride is leased and managed by the Island Conservation Society of Seychelles. The only human inhabitants are the reserve's staff; currently four...
. It often feeds over freshwater and mountain passes but can be seen over most habitats. It feeds on flying insect
Insect
Insects are a class of living creatures within the arthropods that have a chitinous exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae...
s, particularly ant
Ant
Ants are social insects of the family Formicidae and, along with the related wasps and bees, belong to the order Hymenoptera. Ants evolved from wasp-like ancestors in the mid-Cretaceous period between 110 and 130 million years ago and diversified after the rise of flowering plants. More than...
s.
Breeding takes place all year round at a small number of colonies
Bird colony
A bird colony is a large congregation of individuals of one or more species of bird that nest or roost in close proximity at a particular location. Many kinds of birds are known to congregate in groups of varying size; a congregation of nesting birds is called a breeding colony...
in caves. The nest
Nest
A nest is a place of refuge to hold an animal's eggs or provide a place to live or raise offspring. They are usually made of some organic material such as twigs, grass, and leaves; or may simply be a depression in the ground, or a hole in a tree, rock or building...
is bracket-shaped and made of strands of lichen
Lichen
Lichens are composite organisms consisting of a symbiotic organism composed of a fungus with a photosynthetic partner , usually either a green alga or cyanobacterium...
and casuarina
Casuarina
Casuarina is a genus of 17 species in the family Casuarinaceae, native to Australasia, southeast Asia, and islands of the western Pacific Ocean. It was once treated as the sole genus in the family, but has been split into three genera .They are evergreen shrubs and trees growing to 35 m tall...
needles held together by saliva
Saliva
Saliva , referred to in various contexts as spit, spittle, drivel, drool, or slobber, is the watery substance produced in the mouths of humans and most other animals. Saliva is a component of oral fluid. In mammals, saliva is produced in and secreted from the three pairs of major salivary glands,...
. One white egg
Egg (biology)
An egg is an organic vessel in which an embryo first begins to develop. In most birds, reptiles, insects, molluscs, fish, and monotremes, an egg is the zygote, resulting from fertilization of the ovum, which is expelled from the body and permitted to develop outside the body until the developing...
is laid and is incubated
Avian incubation
Incubation refers to the process by which certain oviparous animals hatch their eggs, and to the development of the embryo within the egg. The most vital factor of incubation is the constant temperature required for its development over a specific period. Especially in domestic fowl, the act of...
for about 25 to 30 days. The young birds are fed by both parents and fledge
Fledge
Fledge is the stage in a young bird's life when the feathers and wing muscles are sufficiently developed for flight. It also describes the act of a chick's parents raising it to a fully grown state...
after 42 days.
The species is classified as Vulnerable
Vulnerable species
On 30 January 2010, the IUCN Red List of Threatened Species identified 9694 Vulnerable species, subspecies and varieties, stocks and sub-populations.-References:...
by the IUCN due to its small population (2,500 to 3,000 birds) and limited number of breeding sites. Threats include disturbance, use of insecticide
Insecticide
An insecticide is a pesticide used against insects. They include ovicides and larvicides used against the eggs and larvae of insects respectively. Insecticides are used in agriculture, medicine, industry and the household. The use of insecticides is believed to be one of the major factors behind...
s and predation by introduced Barn Owl
Barn Owl
The Barn Owl is the most widely distributed species of owl, and one of the most widespread of all birds. It is also referred to as Common Barn Owl, to distinguish it from other species in the barn-owl family Tytonidae. These form one of two main lineages of living owls, the other being the typical...
s and cat
Cat
The cat , also known as the domestic cat or housecat to distinguish it from other felids and felines, is a small, usually furry, domesticated, carnivorous mammal that is valued by humans for its companionship and for its ability to hunt vermin and household pests...
s.