Life Of The Great Gray Owl, The Largest In America | Our World

It's March in North America and on the lower slopes of the Rocky Mountains, winter is easing its grip. These northern forests are rich in wildlife. The wooded hillsides and the meadows that separate them are the home of a remarkable hunter. These are the killing grounds of the great grey owl. At around two feet in height, the great grey is America's largest owl. Almost as soon as the snow begins to recede, the owls start looking for a suitable nesting place. Adult great grey owls have few natural enemies, but a goshawk is still watched carefully as it flies overhead. Owls don't build their own nests. They simply reuse those made by other birds in previous years. These can be either high in the branches or in old broken trees. Old goshawk nests are a particular favorite and this one seems to be in good condition. Great grey owls do not mate for life, but they do usually return to the same nest area year after year. It's the bird's individual fidelity to the nest site rather than to each other that often brings them back together again each spring, as long as there's plenty of food in the area. Mutual preening is a very important part of their courtship behavior. The pair's movements appear highly synchronized. A red-tailed hawk flies overhead and the female edges closer to her mate. It's the female that seems to make the final selection of a suitable nest in the chosen area. Apart from the state of the nest, an important factor is the quality of the hunting in the surrounding meadows and clearings. She lays her first egg sometime between the end of March and the beginning of May. Subsequent eggs are laid every one or two days, so in a typical clutch of four, there may be over a week between the first and the last egg being laid. The female starts incubating with the appearance of the first egg. Each egg requires 28 days of constant warmth and attention. She relies on her mate for food. Great greys nest very early in the season to have the pick of the nests, and a late fall of snow is the price they often have to pay. Provided it's not too deep, the snow does not impair the hunting skills of the male owl. Small rodents, mice, voles, and in this area, especially gophers, form the bulk of the owl's prey. The owl can hear faint movements of his prey moving around in tunnels beneath the snow. His mate sits patiently on the nest. Occasionally she turns the eggs, but quickly settles back down to protect them from the icy cold air. Her mate continues in his search for prey. He swoops down on silent wings and thrusts his talons through 10 inches of snow to seize his quarry without even seeing it. As he returns with his prize, the female owl utters a soft, mellow hoot to encourage him. A neighbouring male may sometimes wander into the pair's feeding territory. If he stays around too long, he'll be seen off by the resident male. The female swallows the gopher whole and awaits the next offering. The male swoops again, successfully. All he leaves is a distinct impression in the snow made by his body and wings. Although he's a highly successful hunter, she may have a long wait. A coyote meanders its way through the trees on the lookout for rodents and other small animals that it competes for with the owls. It passes under another great grey owl nest. It's the second year that this female has used this old goshawk nest and the structure, well flattened by two earlier broods of chicks, is beginning to collapse. Although she's sitting tight, there's little chance that she will be successful in raising this clutch. Two eggs have already rolled out of the nest and are well chilled, but she tries to roll them back under her body. Her efforts are in vain and she settles down on her remaining three eggs. With the next high wind, the whole nest will probably go crashing to the ground. Back at the other nest, the owls have been more successful. Five weeks after the first egg was laid, all the chicks have been hatched. The female remains on the nest with her offspring. The male now needs to catch enough gophers to feed himself, his mate and their four chicks. In heavy snow, the owl will be forced to move a long way from its normal range, but this owl watches over a rich hunting ground. The receding snow reveals the spoil heaps of earth from the gopher burrows. Beneath the surface, a gopher is busy feeding on plant roots. Above it, the owl is following every move it makes. One of the owl's ears is slightly higher than the other. It's this that gives the owl the remarkable ability of judging exactly where a sound is coming from. Although its head can rotate through 270 degrees, this owl prefers to walk around its vantage point. Its fine sense of hearing, coupled with its excellent eyesight, means that few movements escape its attention. At the nest, the female and the chicks await the next meal. While the chicks are this small, she has to tear the rodents up into small pieces and offer the chunks to her offspring in turn. The chicks grow rapidly. The oldest could be over a week older than the youngest and twice its body weight. The larger chicks push their way to the front of the queue. If food is scarce, the younger chicks may not survive. Beneath the surface of the soil, the gophers are busy in their burrows. They'll remove any debris or pebbles that fall into their tunnel. The owl is listening, while the gopher continues unawares. He seizes the gopher and his talons through the loose earth and kills it using his beak. The chicks are now around two weeks old and big enough to swallow voles and gophers whole. All four are doing well. Their parents made a good choice of nest. Sixty feet below, another woodland bird, the ruffed grouse, is advertising for a mate. As summer approaches, the rocky mountain woodlands burst into blossom. The male is still doing all the hunting. By now, those talons will have seized several hundred rodents since the start of the season. His chicks still have a lot of growing to do, so the great grey owl sits and waits on the edge of a clearing, listening for the slightest rustle. He doesn't have long to wait. A dandelion mysteriously disappears beneath the soil. It's being dragged down by a gopher into its subterranean tunnel. The owl watches and listens and scours the ground immediately in front of it. The owl thrusts its talons through the soil into the tunnel and seizes the unsuspecting gopher. By now, the chicks are quite large and the female receives her mate's catch on a nearby branch. The nest is getting a little overcrowded. The owlets are now a month old and the older ones will soon be ready to leave the nest. Their fluffy down is gradually being replaced by their true flight feathers. The forest floor is over 60 feet below and scattered beneath the nesting tree lie pellets of indigestible fur and bones coughed up by the female before she nested. Since laying her eggs, she has dropped her pellets elsewhere to avoid attracting predators to the site. By now, the chicks are big enough to be left alone for longer periods and the female takes time off for a much-needed bath. While their mother is away bathing, there's a sudden shower of rain. But without their mother's protection, all the chicks can do is sit it out. She pays great attention to the condition of her flight feathers. Each one is carefully preened. Her chicks watch attentively. Their turn will soon come. Although still only four weeks old, they will somehow have to get from their nest to where the mule deer is walking 60 feet below. It's not surprising that they appear a little apprehensive. They will leave the nest before they're fully fledged, a time when they're incapable of flight. The chicks venture further out along the branches that surround the nest. But there's no other way to leave. The only route is straight down. The female owl preens the largest chick as it prepares to leap. One safely down. Three more to go. After such a leap, it takes a few minutes for the owlet to compose itself. And then it walks off along a fallen log to find a safe place to shelter. Soon, all the chicks have left the nest, but they will remain in the immediate area. Although they'll be ready to fly in a month from now, they will continue to rely on their parents for up to 16 weeks. No sooner have they reached the ground than they start to make their way back up into the trees in order to escape from predators, such as coyotes, weasels, and their own cousins, horned owls. But it's much more difficult going up than it was coming down. Now they have all left the nest, the female owl will also hunt for gophers. She feeds and preens chick number one while her mate attends to chicks two and three. Chick four has managed to climb to the top of an old tree stump where it waits to be fed. The chicks are still very vulnerable to predators at this stage and so by dispersing around the nest site, the chances of them all being found by a predator are greatly reduced. All four chicks have survived. Testimony to their parents' choice of nest site and feeding territory. The adult owls will probably return independently to this same area next year and may even nest together once again. But for the chicks, which are now testing their wings for the first time, it's a different story. On average, 50% of the owlets will not survive their first winter. They will fall victim to starvation or be killed by traffic on roads. Some may even be shot. Many will survive and they too will return to breed in these high rocky mountain forests. Stronghold of North America's largest owl.