Northern California is home to many of the owls found in North America: Great Gray, California Spotted, Barred, Great Horned, Western Screech, Flammulated, Northern Saw-whet, Northern Pygmy, Long-eared, Short-eared, Burrowing, Barn Owl. These species cover all territories, from plains to high mountains, forests to fields, farms to back yards.
Owls are considered raptors because they have killing talons and ripping beaks. One or another of them hunts everything from the smallest cricket to the fattest skunk. There are many differences, DNA not the least, that separate owls from the various diurnal raptors: owls do not have crops; because most of them hunt in dim light, they have poor color vision and unlike hawks and falcons, only a single focal point (area of enriched receptors) on the retina. None flies fast; all except the Burrowing Owl and Northern Pygmy fly silently. Most hunt as much by sound as by sight, and have developed special ears. Unlike humans, owls’ special hair cells in the cochlea will regenerate. Owls, unlike hawks but like falcons, do not build nests. They take over the nests of other animals or live in cavities.
Part I – Great Horned Owl, Northern Spotted Owl, Western Screech Owl
Great Horned Owl (Bubo virginianus) Rightly called the Tiger of the Forest, this large hunter preys on a wide variety of mammals, birds, and reptiles. It is particularly fond of jackrabbits and skunks, and is not averse to taking the occasional house-cat left out at night. This impressive owl has protective coloring that makes it look like tree bark, allowing it to sleep safely in the daytime, and great golden eyes and peaked “horns.” These “horns” or “ear tufts” have nothing to do with hearing, but probably do have something to do with communication. The GHO lays eggs in January in stolen or abandoned hawk nests or caves or large cavities. The young hatch in February and March and remain dependent on their parents far longer than is true of most birds – sometimes until early autumn. This is the owl we hear in towns, suburbs, and forests calling out a deep “Hooo-hoo-hoo.” Though, like most raptors, the female GHO is larger than the male, she has a higher-pitched call.
California Spotted Owl (Strix occidentalis occidentalis) Cousin to the Northern Spotted, famous poster child for old-growth forests, this subspecies nests in the Sierra and Coastal ranges, hunting flying squirrels and wood rats. Its spotted feathering makes it blend in with sunlight dappling a tree trunk, and its dark eyes and round face give it a gentle expression. It is, in fact, rather too tame for its own good, sometimes allowing people to walk up to it. The preservation of old forests is important for all subspecies of this bird, which has adapted to that dark, close environment and to the small mammals that live there. The Spotted’s larger cousin, the Barred Owl (Strix varia Barton), which looks very like it, is much more adaptable – can eat anything (including a Spotted!) and live in many habitats, even near people. This owl is moving into California, down the Coastal Range, competing and sometimes interbreeding with the more vulnerable Spotted Owl. In a changing world, adaptability can mean survival.
Western Screech Owl (Megascops [once Otus] kennicottii) Seen up close, these owls resemble miniature Great Horned Owls, with cryptic coloring and ear tufts. They are a successful species, adapting to life near humans, even moving into towns and cities, wherever there are large trees with nice cozy holes. Hunting at dawn and dusk, these birds capture small rodents, reptiles, and insects, especially large moths, which they snatch from the air. Before devouring their moths, Screeches remove the wings – if you find a pile of wings under a tree, you’ll know who is coming there to eat. You may also find pellets – indigestible leavings from the owls’ meals, which are compacted in the gizzard and then regurgitated, usually once a day. Screech Owl pellets are about the size of a quarter. Larger owls produce much larger pellets, even containing whole skeletons of their prey, since owls do not have the hawk’s strongly acidic digestive juices capable of “melting” large bony bits. Unfortunately for the Screech, the larger owls often target their small cousins, so it is not unheard of to find small owl bones in the pellets of the larger ones.
No wonder, then, that Screech Owls, though they are colored exactly like oak bark, and so are well camouflaged, prefer the safety of their little hidey-holes during the day. They use cavities created by fallen limbs, abandoned woodpecker holes, or even man-made boxes when the opening is the right size. They will lay eggs and raise chicks in the same safe crevice in the early spring and summer months.
Incidentally, these birds don’t live up to their common name: instead of a screech, they make a warbling noise, often descending in pitch, or a series of shorter warbling hoots. Among these owls, as with most raptors, the ladies are larger than the gentlemen, but the male owl’s voice is lower and louder. Their new scientific name, recently changed from “Otus” to “Megascops,” is more apt. “Scop” is Old English for a bard or musician, and is the genus name of many small owls in Europe. “Mega” means big, so the Western Screech Owl is the big little musical owl, named for the naturalist, Robert Kennicott.
(Part II will present more owl species)