Owls | Strigiformes

Uilen | Owls | Rapaces nocturnas

Hunters with a large, broad head in which both eyes face forward, so that the fields of view overlap and the bird sees depth; the eyes are tubular and fixed in their sockets, which is why an owl turns its whole head, well over half a turn thanks to fourteen neck vertebrae. A disc of short, stiff feathers around each eye guides sound to the ear openings, and in a number of species those openings sit at unequal heights, so a sound can be placed in the vertical as well. The plumage is soft and in most species the outer primary carries a comb-like leading edge, so the wingbeat is all but silent; the outer toe is reversible and the claws are long and strongly curved. Prey goes down whole and what will not digest comes back up as a pellet. The white, almost round eggs are laid without any nest building in a tree hole, an old woodpecker hole, a rock crevice or a disused nest. The Andes and the west coast hold two families side by side: the barn owls, represented here by the American Barn Owl, with a heart-shaped disc, and the far richer typical owls, from pygmy owls and screech owls of the cloud forest to the Spectacled Owl of the Amazonian lowlands.

Famílias desta ordem

Bay owls and barn owls | Tytonidae1 espécieThe facial disc is heart-shaped and drawn down into a narrow point; the eyes are small and dark for an owl, the head is narrow and the legs are long and feathered to the toes. The inner toe is as long as the middle toe, and the claw of that middle toe carries a row of fine teeth used to comb the disc clean; the breastbone is fused with the wishbone. Hooting is absent: these birds hiss, snore and shriek. They hunt low and quartering over open rough ground, almost entirely on mice and shrews, and breed in a dark cavity in a building, cliff or tree; clutch size follows the rodent supply, so a good year can bring two broods and a poor one none at all.
Owls | Strigidae37 espéciesThe facial disc is round and the eyes are large, with an iris ranging from yellow to almost black; several species carry two erectile feather tufts on the head, which have nothing to do with hearing but do break up the head's outline. The inner toe is shorter than the middle toe and the middle claw is smooth. In this guide the family numbers 41 species in ten genera, from the Long-whiskered Owlet (Xenoglaux), one of the smallest owls in the world, found only in a small area of cloud forest in northern Peru, to the horned owls (Bubo) of more than a kilo. Screech owls (Megascops) and pygmy owls (Glaucidium) are numerous, with species in every altitudinal zone from the Amazonian lowlands to the treeline; the pygmy owls also hunt by day and carry two dark spots on the nape that act as a second pair of eyes, and the Peruvian Pygmy Owl lives in the dry forest and cactus scrub along the west coast. Large species such as Spectacled Owl and Crested Owl live in lowland forest at the foot of the Andes, and the Buff-fronted Owl (Aegolius) in cloud forest. The voice consists of low, far-carrying notes, trills or whistled series that hold the territory, and is usually the first thing by which the species is known. Nesting is in a tree hole, an old nest of another bird, on a cliff ledge or, as in the Burrowing Owl of the coastal desert and the puna, in a burrow in the ground; the female incubates and broods, the male brings in the food.