The lesser swallow-tailed swift, a slender avian species, graces the skies with its elegant form. Measuring between 12.7 to 13 cm in length and weighing approximately 18 grams, it is a creature of remarkable agility. Both sexes share a similar plumage, predominantly black with a striking white throat and upper breast. The rear flanks are adorned with squarish white patches, and the bird's long, narrow wings and forked tail, typically held closed, complete its distinctive silhouette.
When observing this swift, look for its long, narrow wings and deeply forked tail, which it often keeps closed. Its black body contrasts with the white throat and upper breast, and the white patches on the rear flanks are telltale markers. The bird's flight is rapid and fluttery, a spectacle often observed high in the sky.
The lesser swallow-tailed swift is a denizen of the edges and clearings of lowland tropical evergreen forests, secondary forests, cultivated areas, river corridors, and even human-populated regions. It thrives up to elevations of 1,500 meters in Guatemala and Ecuador, though it is more commonly found at lower altitudes.
This swift's range extends from southern Mexico through Central America and into every mainland South American country, save for Argentina, Chile, Paraguay, and Uruguay. It is also a resident of Trinidad.
A year-round resident within its range, the lesser swallow-tailed swift exhibits a flight that is both swift and agile, often soaring at great heights. It is less gregarious than other swifts, typically seen alone or in pairs, and feeds above other swift species, except for those in the genus Cypseloides.
The vocal repertoire of this swift includes a reedy or wheezy phrase of fast twittering notes, described as 'pzeee-pzi-titititititi-ti-ti-pzeee!' and a repeated, drawn-out 'pzeeeh'. These calls are often emitted during its high-altitude flights, sometimes rendering them inaudible to the human ear on the ground.
The breeding season of the lesser swallow-tailed swift varies geographically, with nesting typically occurring in the local spring and summer. The nest is a tubular structure, crafted from plant material and saliva, and can be found attached to branches or vertical surfaces. Both parents share the duty of incubating the two or three white eggs laid within.
As an aerial insectivore, the lesser swallow-tailed swift feeds primarily on flying insects, with a diet in Venezuela observed to consist mainly of Diptera, supplemented by Homoptera and Hymenoptera, among others.
The IUCN has classified the lesser swallow-tailed swift as Least Concern. With an estimated population of over 500,000 mature individuals and an extensive range, the species does not face any immediate threats, although its numbers are believed to be in a slow decline. It is generally considered uncommon to locally fairly common within its habitat.