Rostzwergkauz

Bestimmung

The ferruginous pygmy owl is small, typically 15 cm (5.9 in), and stocky with disproportionately large feet and talons. The crown has elongated white/buff streaks, the wing coverts have white spots, and the underparts are heavily streaked white. There are prominent white supercilia above the facial disc. There are two dark spots on the nape, often termed "false eyes" by birders. Otherwise, its overall color is highly variable, ranging from grey-brown with a black-and-white barred tail to rich rufous with a uniform rufous tail. Sexes are similar with females slightly larger and often more reddish. The flight is often undulating in motion, similar to that of many woodpecker species.<p>The call is a whistled hoo-hoo-hoo-hoo, usually in E flat. It is easily imitated, and is used by birdwatchers to attract small birds intent on mobbing the pygmy owls.

Taxonomie

The ferruginous pygmy owl was formally described in 1788 by the German naturalist Johann Friedrich Gmelin in his revised and expanded edition of Carl Linnaeus's Systema Naturae. He placed it with all the other owls in the genus Strix and coined the binomial name Strix brasiliana. Although not cited directly, Gmelin's description was ultimately based on the "Cabure" that had been described in 1648 by the German naturalist Georg Marcgrave in his Historia Naturalis Brasiliae. The ferruginous pygmy owl is now placed with 28 other small owls in the genus Glaucidium that was introduced in 1826 by the German zoologist Friedrich Boie. The genus name is from Ancient Greek glaukidion meaning "little owl" or "owlet". It is diminutive of glaux meaning "owl".<p>Thirteen subspecies are recognised:<p>Trinidad, as well as other localities, have endemic subspecies of the Glaucidium brasilianum owl. Recent genetics work has found substantial differences in ferruginous pygmy owls from different regions and members of the northern ridgwayi group are sometimes considered a separate species, Ridgway's pygmy-owl (Glaucidium ridgwayi).

Wissenschaftlicher Name

Glaucidium brasilianum

Autorität

(Gmelin, JF, 1788)

Ordnung

Strigiformes

Familie

Strigidae

Gattung

Glaucidium

Verbreitung und Lebensraum

Zugverhalten

Complete migrants

Verhalten

It can be readily located by the small birds that mob it while it is perched in a tree (up to 40 birds of 11 species have been recorded mobbing one owl).<p>This species is crepuscular, but often hunts by day. It hunts a variety of birds, lizards, other reptiles, amphibians, mammals, and insects. Specific examples of what these owls feed on include grasshoppers, crickets, scorpions, six-lined racerunners, four-lined skinks, Texas spotted whiptails, creamy-bellied thrushes, pale-breasted thrushes, eared doves, and mice.<p>The breeding season is from late winter to early spring. It is a cavity nesting bird (tree and columnar cactus cavities), laying one to seven white eggs. Incubation is 28 days, with 27 to 30 days to fledging.

Schutzstatus

The northernmost subspecies, G. b. cactorum, commonly called the cactus ferruginous pygmy owl, was a listed Endangered species under the U.S. Endangered Species Act. It This protected it in south-central Arizona from loss of habitat and buffel grass fires. Buffel grass catches fire very easily, which spreads to cacti, burning the owl's primary habitat. Its range extends over the border into Sonora, Mexico. G. b. cactorum was delisted in 2006. It was also considered to be an Imperiled Subspecies by NatureServe, with the species as a whole considered Secure.

Bestandstrend

declining