Sub-Arctic Great Horned Owl


Sub-Arctic Great Horned Owl
(Bubo Virginianus Subarcticus)


Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Strigiformes
Family: Strigidae
Genus: Bubo
Species: Bubo Virginianus Subarcticus


Largest and palest of the Great Horned Owls.



Distinguishing characteristics:


The Great Horned Owl has had so much written about it that an entire book could be easily devoted to it.

This Owl is known as the 'feathered tiger' and this is no exaggeration. These owls are very fierce and silent hunters who hunt primarily by sound alone. They care little about what might be the source of the rustling in the undergrowth, and they will subdue whatever they attack with deliberate and grim determination.


Here we will focus upon the subspecies of the Great Horned Owl that is captive bred at the Centre, the subarctic race; which is the largest and palest race of the Great Horned owl. This is a nearly white race of the Great Horned Owl, and at a distance it is easily mistaken for a Snowy Owl. Its the second largest of all North American Owl species. Only the Snowy Owl is larger. However, this owls plumage is held looser upon its body, making it often appear larger then the Snowy Owl. This races distinctive off white mixed with pale ashen grey plumage, faint creamy tinge on the upper plumage, pale facial disk with a dark line along its edge, pale yellow eyes, and distinctive ear tufts make this owl immediately identifiable as the Subarctic Great Horned Owl.



Habitat and natural range:


This race of the Great Horned Owl is found at the beginning of the northern tree-line of Canada and the Unites States, and southward to where it gradually interbreeds with other races of the Great Horned Owl. It can be found in Northwestern British Colombia and east through Mackenzie County,and in Alberta to Hudson Bay and south into the United States, where they can be found in parts of Montana, Wyoming and North Dakota. It is found in the Rocky Mountains of west central Canada and south to the western central USA.



Natural diet:


This is a very fierce and highly predatory owl species. It has been known to deplete all prey inside of its five mile square territory within a year or two, then it is often forced to relocate to another area where it continues this process. All manner of prey are to be consumed by this amazingly determined, persistent, capable, and adaptable species. Prey ranges in size from foxes and fishers, to smaller domestic dogs and house cats, right down to diurnal birds, reptiles, amphibians, fish, and even insects. Even other smaller owl species are killed and eaten in its constant quest for fresh prey. This species is capable of swallowing half of a cottontail rabbit in a few quick gulps. Prey is not even deliberately killed. Instead, it is tightly gripped by this owls incredibly powerful talons and eaten, regarless of how difficult the ensuing struggle becomes for the owl. Whether it is alive or dead, prey is eaten by being torn into large chunks and then these chunks are in turn shallowed. Only once all food has been pulled by its beak from between its tightly clenched talons does it finally release its vise like grip. This owl is one of the few natural predators of the North American skunk. In fact, many museum skins of this Owl smell so strongly of skunk spray that they must be kept behind glass, even after decades. Owls have almost no sense of smell, and so to the Great horned Owl, skunks must seem like ideal prey. Skunks are large and contain a lot of food value. Skunks make a lot of noise and do not even attempt to hide their whereabouts. They do not even try to run away or hide, and instead stand their ground. The convenient runway-like markings down their backs must make their detection even easier to the Great horned Owl, which is completely unaffected by being sprayed by the Skunk. Should the skunk happen to spray, the owl will quickly close it's transparent inner eyelids, which act to protect it's sensitive eyes from any possible damage.



Reproduction:


This Owl nests in a wide variety of locations. Its known to nest in the unused nests of other larger birds such as ospreys, eagles, and crows, or in large hollows of trees, upon cliff ledges, in squirrel drays, and in rare cases upon rooftops. It will even nest upon nothing more than the bare ground, or the wide fork in the branches of a tree. No nest is made, and in some cases eggs and or young fall to their deaths when precarious sites are chosen. Courtship sounds, in the form of five syllable hooting; are a familiar sound to most people in urban and wilderness areas of Canada and the Unites States. Its low booming hooting can be easily heard for a distance of 8.04672 km (5 miles).


The Great Horned Owl begins breeding earlier in the year than any other raptor in North America. Nesting begins in February, during the coldest part of the winter. There are usually two, but sometimes as many as four; completely round white eggs. Incubation is done solely, and extremely tightly; by the female alone who does not leave the nest even for a second, not even to defecate. All food is then hunted and subdued only by the male, who in successful years; soon stocks the larder. Stacking the frozen corpses of prey high around the general vicinity of the nest. This owl commonly incubates its eggs with as much as 30.48 cm (1 foot) of snow upon its back! The young are even fed from between their mothers breast feathers, completely by sense of touch while their mother constantly broods them. They are not exposed to the open air until they have reached an age of 2 weeks.


At about six weeks of age the young tumble from their nest, usually unharmed; as they must in order to have room to move about and exercise their developing flight muscles. Throughout the nesting period, the parents are often extremely protective of their young. They can be very dangerous to encounter while nesting, and many people have been severely attacked by this species when it is in defence of its young. The first indication that a person is too close to this owl's nest or young is that the owls will hiss and snap their beaks in a rapid and very menacing manner, while they puff out all their plumage and fan their wings over their back to appear many times their actual size.


Next, if the onlooker does not withdraw, one or both owls will disappear into the surrounding forest, only for one of them to silently reappear directly behind the person or animal that is perceived to be a threat. The eight talons are driven in their full depth which is up to 5.08 cm (two inches), then the owl tightens its fearsome grip. A lot of tissue damage can occur very quickly as the owl twists and tears the flesh. The moment that one of the parent owls releases its grip, the other attacks, completely silently, from the opposite side in exactly the same manner. As the owls grow even more bold, one of them will drop to the ground and flip over upon its back and tail feathers, then will quickly thrust it's talons deep into the underbelly, or in the case of humans: into the crotch of the attacker. This incredible defence of the young will continue until the threat to their nesting efforts either flees, or is killed. Even adult Black bears have been attacked and driven off by such menacing behaviour. It is plain to see why this owl earned the name of feathered tiger!



Notes on Captive propagation (at the Centre):


Having read the above paragraph, it will come as no surprise to learn that at the Centre we must take some serious precautions whenever we have to enter an aviary containing breeding Subarctic Great Horned Owls. Steel home made full body armour, along with very heavy leather welding gloves, and a skidoo helmet with a solid visor, are mandatory equipment when we must enter to band the young owlets. This is done as fast and as carefully as is possible, and we are very glad to get out of there again. These owls are wonderful breeders and parents.


It is rather difficult to determine their gender, and even they have this difficulty. We have even had a pair consisting of two females lay eggs side by side within the same nest, and then incubate these unfertilized eggs faithfully! These owls mate for life and will refuse to take a new mate if their chosen mate is anywhere within their incredible range of hearing. The young are as playful as kittens, and soon trample down any vegetative growth in their aviary while they comically practice their pouncing, even before they can fly.



Circumstances affecting Conservation:


The Great Horned Owl in general, is not currently experiencing any particularly negative impact upon its populations. There are currently about five million Great Horned Owls in the wild in north and South America. That said, the Subarctic Great Horned Owl, being generally a sub-arctic species is a subspecies to keep a watchful eye upon. This is due to the fact that it is a good indicator species for the fragile northern forests of Canada and the United States. With these areas being under increasing pressure and development, as well as being profoundly affected by global warming; any decline in the wild populations of the Subarctic Great Horned Owl would be an early warning of something really serious affecting the northern ecosystem.

Notice:

If you have found an injured bird of prey (hawk, falcon, owl, etc.), contact the Centre and our experienced staff can assist in determining what steps should be taken to ensure the bird receives the best possible care.

contact

Havelock, Ontario K0L 1Z0

Telephone : +1 705 778 5273

Email : staff