Burrowing Owl

Identificazione

Burrowing owls have bright eyes; their beaks can be dark yellow or gray depending on the subspecies. They lack ear tufts and have a flattened facial disc. The owls have prominent white eyebrows and a white "chin" patch which they expand and display during certain behaviors, such as a bobbing of the head when agitated.<p>Adults have brown heads and wings with white spotting. Their chests and abdomens are white with variable brown spotting or barring, also depending on the subspecies. Juvenile owls are similar in appearance, but they lack most of the white spotting above and brown barring below. The juveniles have a buff bar across their upper wings and their breasts may be buff-colored rather than white. Burrowing owls of all ages have grayish legs longer than those of other owls.<p>Males and females are similar in size and appearance, so display little sexual dimorphism. Females tend to be heavier, but males tend to have longer linear measurements (wing length, tail length, etc.). Adult males appear lighter in color than females because they spend more time outside the burrow during daylight, and their feathers become "sun-bleached". The burrowing owl measures 19–28 cm (7–11 in) long and spans 50.8–61 cm (20–24 in) across the wings, and weighs 140–240 g (5–8 oz). As a size comparison, an average adult is slightly larger than an American robin (Turdus migratorius).[failed verification]

Tassonomia

The burrowing owl was formally described by Spanish naturalist Juan Ignacio Molina in 1782 under the binomial name Strix cunicularia from a specimen collected in Chile. The specific epithet is from the Latin cunicularius meaning "burrower" or "miner". The burrowing owl is now placed in the genus Athene that was introduced by German zoologist Friedrich Boie in 1822.<p>The burrowing owl is sometimes classified in the monotypic genus Speotyto based on an overall different morphology and karyotype. Osteology and DNA sequence data, though, suggest that the burrowing owl is a terrestrial member of the little owls (Athene), and it is today placed in that genus by most authorities.<p>A considerable number of subspecies have been described, but they differ little in appearance and the taxonomy of several of them needs to be validated. Most subspecies are found in/near the Andes and in the Antilles. Although distinct from each other, the relationship of the Florida subspecies to (and its distinctness from) the Caribbean birds is not quite clear.<p>The 18 recognised subspecies, of which two are now extinct, are:<p>includes A. c. partridgei (Olrog, 1976): Corrientes burrowing owl – Corrientes Province, Argentina, probably not distinct from A. c. cunicularia<p>A paleosubspecies, A. c. providentiae, has been described from fossil remains from the Pleistocene of the Bahamas. How these birds relate to the extant A. c. floridana – that is, whether they were among the ancestors of that subspecies, or whether they represented a more distant lineage that completely disappeared later – is unknown.<p>In addition, prehistoric fossils of similar owls have been recovered from many islands in the Caribbean (Barbuda, the Cayman Islands, Jamaica, Mona Island and Puerto Rico). These birds became extinct towards the end of the Pleistocene, probably because of ecological and sea-level changes at the end of the last ice age rather than human activity. These fossil owls differed in size from present-day burrowing owls and their relationship to the modern taxon has not been resolved.

Nome scientifico

Athene cunicularia

Autorità

(Molina, 1782)

Ordine

Strigiformi

Famiglia

Strigidae

Genere

Athene

Areale e habitat

Before European colonization, burrowing owls probably inhabited every suitable area of the New World, but in North America, they have experienced some restrictions in distribution since then. In parts of South America, they are expanding their range due to deforestation. The western burrowing owls (A. c. hypugaea) are most common in the Rocky Mountain Arsenal National Wildlife Refuge, as well as in most of the western states. Known resident populations inhabit areas of Colorado, Arizona, New Mexico, Texas and California, where their population is reportedly threatened by human encroachment and construction.<p>Burrowing owls range from the southern portions of the western Canadian provinces (British Columbia, Alberta, Saskatchewan, Manitoba) and all the way through Mexico to western Panamá. They are also found across the state of Florida, as well as some Caribbean islands. In South America, they are fairly common, and are known to inhabit every country on the continent, with the exception of the dense Amazon rainforest interior and the highest ranges of the Andes Mountains. Their preference is for the cooler, possibly sub-tropical coastal and temperate regions. South of the Amazon, their population seems to again rebound, as they are widely distributed from southern Brazil and the Pantanal down to Patagonia and Tierra del Fuego.<p>Burrowing owls are year-round residents in most of their range. Birds that breed in Canada and the northern U.S. usually migrate south to Mexico and the southern U.S. during winter months.

Migrazione

Migratori completi

Comportamento

Comportamento migratorio: Migratori completi.

Conservazione

Tendenza della popolazione: in diminuzione.

Tendenza della popolazione

in diminuzione