may be the most efficient predator that has ever lived. Its
hunting is based on a combination of stealth, remarkable powers of prey
detection and location, and the application of
all out of proportion to its size.
Victims of a Great Horned Owl’s silent aerial attack
typically are not aware of the owl’s presence until they are within the
vice-like grip of the owl's talons.
A great horned owl weighs between two to
four pounds, has a wing span of 36 to 60 inches, and stands from 18
inches to 2 feet tall. As with all raptor species, the female is the
larger of the two sexes.
The great horned owl's “ear tufts” are not ears at all, but feathers which aid in camouflage, and may also indicate their mood. Owls can hear noises ten times fainter than our hearing permits, enabling them to locate prey they cannot see, for example, prey scurrying through the tunnels they excavate under snow pack or prey obscured by brush. The owl's asymmetrical ears are hidden under the dark edges of the facial disk, which is split by the beak and the forehead. The facial dish directs sound to the ears, and the right ear is positioned higher under the disk than the left ear, causing sounds to reach one ear a fraction of a second before it reaches the other. The owl tilts and turns its head until the sounds equalize, and because the owl cannot change the direction of its eyes without rotating the head, the owl is at that moment, staring directly at the location of its prey.
Think of the large Adirondack birds you've seen, for example, wild turkey, grouse especially, or any type of water fowl. Among the features they have in common, is how much noise their wings make while in flight. Owls are not fast fliers, with a top speed of about 40 mph. However, like virtually all owls, the great horned’s flight is silent due to soft feathers on the edges of its wings. Other birds preen the ends of the wings to hook the ends of the feathers together so they can fly efficiently. Owls do not. What they lose in speed as a result, they make up in stealth, because their flight is totally silent. As the owl drops from its perch and glides towards the sound, silent flight also enables the continuous audible triangulation of the prey's location as the owl closes in.
Great horned owls have thick legs and heavy talons. Like our thumbs, the outside talon is opposable, which allows an owl to switch between a perching posture, with three toes in front and one in the rear, and a hunting and grasping posture, with two toes in front and two in the rear, allowing the owl to frame a mammal's spine with its talons as it strikes. The crushing power in a Great Horned’s talons is reputed to be an incredible 500 lbs. per square inch, ten times stronger than the grip of a human hand, so once the talons sink through the prey’s back, most prey are killed instantly. When you hear a biologist joking, that when his time is up, he wants to be taken by an owl, he's saying that the prey of a great horned owl literally do not know what hits them. The great horned owl is the "Jack the Ripper" of the animal kingdom, waiting in silence to deliver an overpowering attack.
Raptors have no teeth, so smaller prey are swallowed whole, while larger prey are torn into manageable chunks, using the beak and talons. The forward talon has a serrated edge, so that the owl can tear lage prey by sinking its talons, reaching down with the beak, and lifting its head up and back. Since feeding on the ground may expose the owl to possible ambush, the great horned owl, the only raptor which can fly while carrying prey equal to its own weight, will attempt to fly its prey to a secure perch on which to safely swallow it. Horny pads under the owls toes allow the owl to control struggling prey as the owl flies.
The great horned owls eat everything from skunks—raptors have a very limited sense of smell—to housecats, whose disappearance is blamed more often than is deserved, on our Adirondack coyotes. Muskrats are a favorite, as are rabbits, squirrels, weasels, minks, martins, bats and anything else they can catch. They are a main predator of the crow, and take other birds including hawks and smaller owls. Although it is only the size of a redtailed hawk, great horned owls are extremely aggressive, and have been known to drive even bald eagles from their nests.
Great horned owls nest very early in the season and the female can often be seen incubating her eggs in February, covered with snow. Just as this "winged tiger" rules the night, its diurnal counterpart, the red tailed hawk, handles the day shift, preying on many of the same animals. Their territories may overlap, but great horned owls nest earlier in the winter, and since they do not build nests, but rather tend to appropriate the work of others, may take over last year's red tail nest. Great horned owls may also take over a large squirrel's nest, or use any cavity, such as in a tree, on a ledge, etc. On occasion, these raptors may take each other's chicks, and a great horned owl may attack a red tail's nest while the hawks are roosting, but generally the two birds of prey will coexist in the same territory. The great horned owl's clutch of eggs averages two, which the female incubates for about 5 weeks, continuing the incubation until the hatched chicks are about two weeks old. Chicks begin crawling out of the nest to perch on nearby branches, at 6 weeks, about a week before they start to fly. See the note about "Poodle" branching below.
Digestion & other yucky stuff
a crop, the throat pouch where other birds store food prior to
digestion. Food goes down the esophagus to the proventriculus, a
stomach-like organ, where
enzymes, acids and mucus begin to break the food down. Next stop is the
gizzard, or ventriculous, which separates out the indigestible parts,
like bones, teeth and fur, which will be regurgitated later as
grayish-white, sausage-shaped pellets or "castings", within about 24
hours of feeding. The act
of casting signals
that the bird is ready to feed again. Like
reptiles and amphibians, birds have only a single intesinal waste
vent, the cloaca, from which they expunge a fecally acidic white paste
and a clear urinary fluid. The
reproductive organs are also concealed within the cloaca, which is why,
aside from the fact that females are considerably larger, you can not
tell a raptor's sex without a blood test. Owls
often perch on pine branches
high above and along the Wildlife Refuge trail, so look for the
tell-tale castings under the trees, or the whitewash fecal spray on the
trunks and branches.
Not exactly Robin Williams
There is something comically humourless
about owls, in the sense that I've never seen an owl do anything that
appeared to be playful, or fullfilling any need for amusement. While we
often see red tails chasing each other and diving as a part of
courtship, owls appear stiff and serious, always businesslike. Even
their courtship is almost formal, with the bowing and presenting of
Utah, the male, was struck by a car in Utah,
and Artemis, the female, became tangled in barbed wire shortly after
leaving the nest in North Carolina. Poodle, an orphaned fledling, was
released in September.
|Great Horned Owl chicks begin "branching" at about 6 weeks, before they can fly, grasping their way out onto branches around the nest This chick was either a "brancher" who fell, or she was kicked out of the nest by a sibling. "Poodle" was found by two campers in Keeseville. They called us in early May, and reported that the chick was hanging around their campsite. We asked them to try to find the nest, and place the chick underneath, and let Mom take care of her baby. 36 hours later, they called back, and reported that they couldn't find the nest, and that the chick was again hanging around their camp site. We retrieved the chick, and put her pet carrier in with Utah and Artemis, opening the door (left) just to feed her. After a week of this, we left the carrier door open, giving her access to the adult owls, who seemed to ignore her. Two weeks later, she had doubled her weight, and began branching near Utah. Wendy released Poodle (below) in Oct. of '09.|
|Saw Whet Owl||Barn
|Broad Winged Hawk||Swainsons Hawk||Rough
Steve & Wendy Hall
PO Box 360, 977 Springfield Road, Wilmington, NY 12997
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Email us: info@AdirondackWildlife.org