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The Mariana swiftlet or Guam swiftlet (''Aerodramus bartschi'') is a species of
swiftlet Swiftlets are birds contained within the four genera ''Aerodramus'', ''Hydrochous'', ''Schoutedenapus'' and ''Collocalia''. They form the Collocaliini tribe within the swift family Apodidae. The group contains around thirty species mostly confin ...
in the
family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Ideall ...
Apodidae The swifts are a family, Apodidae, of highly aerial birds. They are superficially similar to swallows, but are not closely related to any passerine species. Swifts are placed in the order Apodiformes with hummingbirds. The treeswifts are closely ...
.


Taxonomy

It was formerly lumped with the island swiftlet (''Aerodramus inquietus'').


Description

The swiftlet is about 11 cm in length with a dark grey-brown head and upperparts. Its throat and upper breast are grey-white with the rest of the underparts darker grey. The tail has a shallow fork and the plumage lacks gloss.


Distribution and habitat

The swiftlet is found in
Guam Guam (; ch, Guåhan ) is an organized, unincorporated territory of the United States in the Micronesia subregion of the western Pacific Ocean. It is the westernmost point and territory of the United States (reckoned from the geographic cent ...
as well as in
Saipan Saipan ( ch, Sa’ipan, cal, Seipél, formerly in es, Saipán, and in ja, 彩帆島, Saipan-tō) is the largest island of the Northern Mariana Islands, a commonwealth of the United States in the western Pacific Ocean. According to 2020 es ...
and
Aguiguan Aguiguan (also Aguigan and Aguihan, based on the Spanish rendition of the native name, Aguijan, which is still used) is a small bean-shaped coralline island in the Northern Mariana Islands chain in the Pacific Ocean. It is situated south-west o ...
in the
Northern Mariana Islands The Northern Mariana Islands, officially the Commonwealth of the Northern Mariana Islands (CNMI; ch, Sankattan Siha Na Islas Mariånas; cal, Commonwealth Téél Falúw kka Efáng llól Marianas), is an unincorporated territory and commonwea ...
, and is locally extinct on Rota and
Tinian Tinian ( or ; old Japanese name: 天仁安島, ''Tenian-shima'') is one of the three principal islands of the Commonwealth of the Northern Mariana Islands. Together with uninhabited neighboring Aguiguan, it forms Tinian Municipality, one of th ...
. It was also introduced successfully to
Oahu Oahu () ( Hawaiian: ''Oʻahu'' ()), also known as "The Gathering Place", is the third-largest of the Hawaiian Islands. It is home to roughly one million people—over two-thirds of the population of the U.S. state of Hawaii. The island of O� ...
in the
Hawaiian Islands The Hawaiian Islands ( haw, Nā Mokupuni o Hawai‘i) are an archipelago of eight major islands, several atolls, and numerous smaller islets in the North Pacific Ocean, extending some from the island of Hawaii in the south to northernmost Ku ...
in the early 1960s, though the population there remains small. Its natural
habitat In ecology, the term habitat summarises the array of resources, physical and biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species habitat can be seen as the physical ...
s are tropical moist lowland forest,
mangrove forest Mangrove forests, also called mangrove swamps, mangrove thickets or mangals, are productive wetlands that occur in coastal intertidal zones. Mangrove forests grow mainly at tropical and subtropical latitudes because mangroves cannot withstand fre ...
and
grassland A grassland is an area where the vegetation is dominated by grasses (Poaceae). However, sedge ( Cyperaceae) and rush (Juncaceae) can also be found along with variable proportions of legumes, like clover, and other herbs. Grasslands occur natu ...
.


Behaviour

In its natural range the swiftlet builds shallow nests high on the interior walls and ceilings of
limestone Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms when ...
caves, including sites in zones of complete darkness, in colonies of a few to several hundred birds. A single egg constitutes a clutch, but the birds may breed more than once a year. The swiftlets utter twittering and chirping sounds as well as the echolocation clicks used to navigate inside the nesting and roosting caves. Most birds in a colony leave their cave at dawn to forage, returning at sunset to roost. They are aerial feeders that capture small insects in flight over forest and other vegetation.


Status and conservation

The Mariana swiftlet is considered to be
Endangered An endangered species is a species that is very likely to become extinct in the near future, either worldwide or in a particular political jurisdiction. Endangered species may be at risk due to factors such as habitat loss, poaching and invas ...
. The population on Guam declined because of predation by
brown tree snake The brown tree snake (''Boiga irregularis''), also known as the brown catsnake, is an arboreal rear-fanged colubrid snake native to eastern and northern coastal Australia, eastern Indonesia (Sulawesi to Papua), Papua New Guinea, and many island ...
s and the use of agricultural
pesticide Pesticides are substances that are meant to control pests. This includes herbicide, insecticide, nematicide, molluscicide, piscicide, avicide, rodenticide, bactericide, insect repellent, animal repellent, microbicide, fungicide, and lampri ...
s, though it is believed to have subsequently increased to an estimated 900 individuals in 2006. The population on Saipan was estimated in 2005 to consist of about 5400 individuals, though this population is at risk if the
brown tree snake The brown tree snake (''Boiga irregularis''), also known as the brown catsnake, is an arboreal rear-fanged colubrid snake native to eastern and northern coastal Australia, eastern Indonesia (Sulawesi to Papua), Papua New Guinea, and many island ...
becomes established on the island. The estimated size of the Aguiguan population is about 400. The single known breeding colony on Oahu was estimated in 1997 to contain a minimum of 17 breeding pairs. Proposed conservation measures include continued population monitoring and limiting cave disturbance, the prevention of the establishment of brown tree snakes in the
Northern Marianas Islands The Northern Mariana Islands, officially the Commonwealth of the Northern Mariana Islands (CNMI; ch, Sankattan Siha Na Islas Mariånas; cal, Commonwealth Téél Falúw kka Efáng llól Marianas), is an unincorporated territory and commonwea ...
, control of introduced mud dauber wasps and
cockroach Cockroaches (or roaches) are a paraphyletic group of insects belonging to Blattodea, containing all members of the group except termites. About 30 cockroach species out of 4,600 are associated with human habitats. Some species are well-known as ...
es where they damage nests, and the reintroduction of birds to Rota whence they were extirpated in the 1970s.


References

{{Taxonbar, from=Q27581 Mariana swiftlet Birds of Guam Birds of the Northern Mariana Islands Mariana swiftlet Taxonomy articles created by Polbot Endangered fauna of the United States