The white-throated swift (''Aeronautes saxatalis'') is a
swift
Swift or SWIFT most commonly refers to:
* SWIFT, an international organization facilitating transactions between banks
** SWIFT code
* Swift (programming language)
* Swift (bird), a family of birds
It may also refer to:
Organizations
* SWIFT, ...
of the family
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 ...
native to western
North America
North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Car ...
, south to cordilleran western
Honduras
Honduras, officially the Republic of Honduras, is a country in Central America. The republic of Honduras is bordered to the west by Guatemala, to the southwest by El Salvador, to the southeast by Nicaragua, to the south by the Pacific Oce ...
.
[Ryan TP, Collins CT. 2000. White-throated Swift (''Aeronautes saxatalis''). Version 2.0. In: Poole AF, Gill FB, editors. The Birds of North America nternet ited 2018 Oct 3 Ithaca (NY): Cornell Lab of Ornithology. .] Its coastal range extends as far north as Northern California, while inland it has migratory populations found throughout the
Great Basin
The Great Basin is the largest area of contiguous endorheic basin, endorheic watersheds, those with no outlets, in North America. It spans nearly all of Nevada, much of Utah, and portions of California, Idaho, Oregon, Wyoming, and Baja California ...
and Rocky Mountain regions, ranging as far north as southern British Columbia.
White-throated swifts are found in open areas near cliffs, rock faces, or man-made structures, where they roost. Swifts are social birds, and groups are often seen roosting and foraging for flying insects together.
Description
The white-throated swift is medium-sized bird that is primarily black and white.
Its back and wings are blackish-brown or black, and its breast, belly, chin, and throat are white.
In newly molted adults, the dark feathers may have a slight greenish sheen, though this is rarely observable in the field.
Sexes cannot be distinguished by plumage.
Juvenile (first basic) plumage is similar to adult (definitive basic) plumage, but with the feathers on juveniles' heads and necks appearing duller and paler.
Adults are generally 15–18 centimeters in length, and have a tail with a relatively shallow 10 millimeter-deep notch.
Adult swifts weigh between 28 and 36 grams, with a mean weight recorded as 32.5 grams,
[Collins, C. T. and E. V. Johnson. 1982]
Further records of White-throated Swifts utilizing man-made structures
Western Birds nternet ited 2018 Oct 3 13: 25–28. and there is no difference in size between males and females.
The white-throated swift has a wingspan of 35.5 cm. White-throated swifts can appear similar to
American black swift
The American black swift, or more simply black swift (''Cypseloides niger''), is a species of bird that is found from northern British Columbia in Canada through the United States and Mexico to Costa Rica and Brazil. They are also found in the Ca ...
s and
Vaux's swift
Vaux's swift (''Chaetura vauxi'') is a small swift native to North America, Central America, and northern South America. It was named for the American scientist William Sansom Vaux.
Description
This is a small swift, even compared to other ''C ...
s, which also occur in western North America, but they can be distinguished by their white underparts which both other species lack.
Taxonomy
The order in which white-throated swifts are placed is debated, with some taxonomies placing them in
Caprimulgiformes
Nightjars are medium-sized nocturnal or crepuscular birds in the family Caprimulgidae and order Caprimulgiformes, characterised by long wings, short legs, and very short bills. They are sometimes called goatsuckers, due to the ancient folk tal ...
, but others putting them in
Apodiformes
Traditionally, the bird order Apodiformes contained three living families: the swifts (Apodidae), the treeswifts (Hemiprocnidae), and the hummingbirds (Trochilidae). In the Sibley-Ahlquist taxonomy, this order is raised to a superorder Apodi ...
.
[Pellegrino I, Cucco M, Harvey JA, Liberatore F, Pavia M, Voelker G, Boana G. 2017. So similar and yet so different: taxonomic status of Pallid Swift ''Apus pallidus'' and Common Swift ''Apus apus.'' Bird Study nternet ited 2018 Oct 3 64(3): 344–352. .] The difficulty in taxonomic placement is largely due to the morphological similarities between swifts which make determining the history of evolutionary divergence difficult.
At lower taxonomic levels, White-throated swifts belong to the family
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 ...
and the genus ''
Aeronautes.''
''Aeronautes'' includes only two other species, the
Andean swift (''Aeronautes andecolus'') and the
white-tipped swift
The white-tipped swift (''Aeronautes montivagus'') is a species of bird in subfamily Apodinae of the swift family Apodidae.HBW and BirdLife International (2021) Handbook of the Birds of the World and BirdLife International digital checklist of ...
(''Aeronautes montivagus'').
There are two subspecies: ''A. s. saxatalis'', and ''A. s. nigrior''.
The ''A. s. saxatalis'' subspecies comprises birds that winter in North America south to the
Isthmus of Tehantepec in Oaxaca, Mexico, while birds of the ''A. s. nigrior'' subspecies are found wintering below Oaxaca south to Honduras.
Birds of ''A. s. saxatalis'' tend to have a more prominent superciliary streak, darker upper parts, and a broader white abdominal streak than those of ''A. s. nigrior''.
Habitat and distribution
Distribution
White-throated swifts are year-round residents of coastal and southern California, southern Arizona, southern New Mexico, western Texas, central Mexico, and the
Sierra Madre Occidental
The Sierra Madre Occidental is a major mountain range system of the North American Cordillera, that runs northwest–southeast through northwestern and western Mexico, and along the Gulf of California. The Sierra Madre is part of the American C ...
and
Oriental
The Orient is a term for the East in relation to Europe, traditionally comprising anything belonging to the Eastern world. It is the antonym of ''Occident'', the Western World. In English, it is largely a metonym for, and coterminous with, the ...
mountains.
Migratory breeding populations can be found from Arizona and New Mexico north to southern British Columbia, and from central California east to eastern Colorado and Wyoming.
[Bartholomew GA, Howell TR, Cade TJ. 1957. Torpidity in the White-throated swift, Anna Hummingbird, and Poor-Will. The Condor nternet ited 2018 Sep 21 59(3): 145–155. . .] In the southern part of its migratory range, birds arrive in mid-March and depart in mid-October, while in the northern portion, they do not arrive until mid-April to early-May, and depart in late-August to mid-September.
[Small A. 1994. California birds: their status and distribution. Vista (CA): Ibis Publishing Company.] There are two main areas in which non-breeding wintering populations can be found: the first includes southwestern California, eastern Arizona, the
Texas Panhandle
The Texas Panhandle is a region of the U.S. state of Texas consisting of the northernmost 26 counties in the state. The panhandle is a square-shaped area bordered by New Mexico to the west and Oklahoma to the north and east. It is adjacent to ...
, while the second is in El Salvador, Guatemala, Honduras, and the Mexican state of
Chiapas
Chiapas (; Tzotzil language, Tzotzil and Tzeltal language, Tzeltal: ''Chyapas'' ), officially the Free and Sovereign State of Chiapas ( es, Estado Libre y Soberano de Chiapas), is one of the states that make up the Political divisions of Mexico, ...
.
Habitat
Swifts roost in cliffs, bluffs, and canyons, as well as man-made structures like bridges, overpasses, and walls of quarries.
In natural settings, swifts form colonies of as many as 400–500 birds in protected cliff crevices that are generally 6–50 meters above the ground.
[Hanna WC. 1909. The White-throated Swift on Slover Mountain. The Condor nternet ited 2018 Oct 4 11(3): 77–81. . .] White-throated swifts will sometimes roost and nest in amongst colonies of swallows, including
cliff
In geography and geology, a cliff is an area of rock which has a general angle defined by the vertical, or nearly vertical. Cliffs are formed by the processes of weathering and erosion, with the effect of gravity. Cliffs are common on co ...
,
violet-green, and
northern rough-winged swallows.
[Bent AC. 1940. Life histories of North American cuckoos, goatsuckers, hummingbirds, and their allies. Bulletin of the United States National Museum nternet ited 2018 Oct 4 176: 1–506. .] While foraging, white-throated swifts are found flying over meadows, agricultural fields, and open areas along the edges of ridges and hills.
Behavior
White-throated swifts are rapid fliers who rarely land except to roost.
Swifts usually fly 10–100 meters above the ground, and can be observed taking advantage of wind currents and
updrafts to gain speed.
White-throated swifts usually leave their roosts in the morning, and will remain flying and foraging all day until late afternoon or evening. While in flight, swifts can sometimes be observed bathing by hitting the surface of the water with their underside, which is followed by airborne preening.
Occasionally, they will fight with one another while in flight, and may chase or strike other white-throated swifts or
violet-green swallows (''Tachycineta thalassina'').
Diet and predators
Swifts are aerial insectivores who frequently forage in areas of rising air along the edges of canyons, foothills, or mountains to capture insects.
White-throated swifts have also been observed foraging over agricultural lands, and are known to follow harvesting machinery to capture insects disturbed by the equipment. Stomach content analysis has found that beetles, flies, bees, and true bugs (
Hemiptera
Hemiptera (; ) is an order (biology), order of insects, commonly called true bugs, comprising over 80,000 species within groups such as the cicadas, aphids, planthoppers, leafhoppers, Reduviidae, assassin bugs, Cimex, bed bugs, and shield bugs. ...
) constitute a majority of the white-throated swift's diet.
Adult swifts nourish their nestlings by carrying a bolus of arthropods in their
buccal cavity
The buccal space (also termed the buccinator space) is a fascial space of the head and neck (sometimes also termed fascial tissue spaces or tissue spaces). It is a potential space in the cheek, and is paired on each side. The buccal space is super ...
, and feeding it to the young.
Swifts derive most of their water from their diet, but can also be skimming the surface of ponds to drink.
Known predators of White-throated swifts include
peregrine falcon
The peregrine falcon (''Falco peregrinus''), also known as the peregrine, and historically as the duck hawk in North America, is a Cosmopolitan distribution, cosmopolitan bird of prey (Bird of prey, raptor) in the family (biology), family Falco ...
s,
prairie falcon
The prairie falcon (''Falco mexicanus'') is a medium-large sized falcon of western North America. It is about the size of a peregrine falcon or a crow, with an average length of 40 cm (16 in), wingspan of approximately 1 meter (40&nb ...
s, and
American kestrel
The American kestrel (''Falco sparverius''), also called the sparrow hawk, is the smallest and most common falcon in North America. It has a roughly two-to-one range in size over subspecies and sex, varying in size from about the weight of ...
s. When predators are detected, swifts are known to quickly lower their altitude and fly just above the vegetation.
There is no data available on levels of nest predation.
Vocalizations
White-throated swifts make vocalizations while in the air that are described as "staccato chattering",
and may also make a sharp one- or two-note call
or a shrill drawn-out "scree" call.
[Chantler P, Driessens G. 1995. Swifts: a guide to the swifts and treeswifts of the world. Sussex (UK): Pica Press.] In the morning and evening, "twittering" sounds may be made at their roost sites.
Additionally, juveniles may make begging sounds that are higher-pitched versions of the adult's shrill scree call.
Reproduction
During the courtship season, white-throated swifts may perform gliding displays and plummeting courtship falls prior to forming
monogamous
Monogamy ( ) is a form of Dyad (sociology), dyadic Intimate relationship, relationship in which an individual has only one Significant other, partner during their lifetime. Alternately, only one partner at any one time (Monogamy#Serial monogamy, ...
pairs.
Once a pair is established, nests made of plant material and feathers held together with saliva are built on rocky cliff faces or human-made structures.
[Collins CT. 2009. Notes on the breeding biology of the white-throated swift in southern California. Southern California Academy of Sciences nternet ited 2018 Sep 17 109(2): 23–36. .] These nests are usually 8–10 centimeters across, and 2.5–2.8 centimeters deep, and may be used for several years in a row.
An average of 4–5 white matte eggs are laid over the course of 4–6 days, with incubation generally beginning only after the last egg is laid.
In southern parts of their range, egg-laying occurs in April, but in more northerly areas, clutches are usually laid throughout May, with a median first-egg date of May 13.
The incubation period lasts on average 24 days, with swifts weighing approximately 2 grams upon hatching.
Both parents feed the nestlings, and by the time of fledging, swifts may weigh up to 46 grams.
There are no documented cases of swifts attempting a second brood if the first nest fails.
Conservation status
Across North America, white-throated swift populations have declined by 2.8% from 1966–1998, which is considered to be a significant decline.
Such declines could be related to loss of roosting and nesting sites from quarrying, mining, and the demolition of older buildings, as well as reduction in food supply due to pesticide use.
However, in certain areas swift populations appear to have increasing trends, and most populations appear stable.
The patchy distribution of this species makes interpreting these data difficult, but the apparent overall decline is of concern given the concurrent declines of other aerial insectivores.
References
External links
White-throated Swift€“ Cornell Lab of Ornithology
IUCN White-throated Swift€“ IUCN Red List
White-throated Swift€“ Audubon Guide to North American Birds
The White-throated Swift in British Columbia€“ British Columbia Breeding Bird Atlas
White-throated Swift Status€“ Government of Canada Status of Birds in Canada
*
– USGS Patuxent Bird Identification InfoCenter
– Cornell Lab of Ornithology
*
White-throated swifta
Bird of North America Online*
*
*
{{Taxonbar, from=Q606956
white-throated swift
The white-throated swift (''Aeronautes saxatalis'') is a Swift (bird), swift of the family Apodidae native to western North America, south to cordilleran western Honduras.Ryan TP, Collins CT. 2000. White-throated Swift (''Aeronautes saxatalis''). ...
Native birds of Western Canada
Native birds of the Western United States
Birds of the Great Basin
Birds of Mexico
Birds of the Sierra Madre Occidental
Birds of the Sierra Madre Oriental
Birds of the Sierra Madre del Sur
Birds of the Trans-Mexican Volcanic Belt
Birds of Guatemala
Birds of El Salvador
Birds of Honduras
white-throated swift
The white-throated swift (''Aeronautes saxatalis'') is a Swift (bird), swift of the family Apodidae native to western North America, south to cordilleran western Honduras.Ryan TP, Collins CT. 2000. White-throated Swift (''Aeronautes saxatalis''). ...
white-throated swift
The white-throated swift (''Aeronautes saxatalis'') is a Swift (bird), swift of the family Apodidae native to western North America, south to cordilleran western Honduras.Ryan TP, Collins CT. 2000. White-throated Swift (''Aeronautes saxatalis''). ...