The Owl

Most people show an affinity toward owls. Because of their large heads and forward-looking face, owls have the appearance of wisdom.

There are about 236 species of owls in the world in which there are 19 species in North America. Owls can be divided into 2 groups – the Barn and Bay Owls, Family Tytonidae, and all the other owls, Family Strigidae. On Long Island, we have 5 owls that typically nest here: Barn Owl, Great Horned Owl, Long-eared Owl, Short-eared Owl, and Eastern Screech-Owl. Formally the Northern Saw-whet Owl – but it is still a Winter visitor, and there was a remnant population of Barred Owls in the climax forests scattered throughout the northern forests of the island, but that may be gone now. Long Island typically has one species of owl, the Snowy Owl, which is a winter visitor in eruptive years from their northern range when their food supply crashes. Because the south shore’s barrier island’s habitat is similar to this owl’s tundra habitat, that is where this species settles.

Owls are mostly nocturnal, but some are what is known as a combination crepuscular (dawn and dusk) and partially nocturnal. This group doesn’t compete with the totally nocturnal if they share the same territory. Snowy Owls, because of their regular northern, tundra range, can be totally diurnal.

Most owl wings are adapted for silent flight. From the air’s impact on the leading edge of the covert feathers to the hardened, comb-like leading edges of the exposed portions of the primary feathers, the sound of air passing through is negated to almost zero.

Another adaptation for nocturnal owls is sound location. Some species of owls are adapted to hunt in total darkness (but never have to go this far in nature). Unlike bats, owls do not produce a high frequency noise and use it for echolocation. Nocturnal owls have developed a complex mechanism of sound location using sound sensitive feathers in a facial disc. These are called filofethers the visible facial disc covers that group of filofeathers in which the end of those feathers just extends beyond the main feathers of the facial disc. Now these facial discs are parabolic in shape, thus the incoming sound is directed to a focal point (the same principal as the ‘dish’ in a satellite television), and the focal point of the parabola is the ear. When a sound source (prey) makes a noise, the owl will turn its head so the the sound source (prey) is in a direct line in front of the filfeathers. Now the ears are not placed symmetrically on the head, one is actually ‘higher’ on one side of the facial disc than the corresponding ear on the other ear. This allows the time for sound to arrive to reach each ear differently. The skin around the opening of each ear is also different, presumably to further sound source location. Add all this together, and you have the perfect night hunter.