Northern goshawks hurtle through woods in hot pursuit of prey, or ambush unwitting woodland owners who get too close to nests.
A large,dark blur blasts through thick woods, igniting calls of alarm from startled birds and chipmunks. Chasing a hapless victim to almost certain oblivion it eventually disappears, carcass in claws. Sometimes the same form haunts a woodland edge, perched silently, watching and waiting for movements that suggest a meal. That's how I first identified the northern goshawk in our woodland many years ago.
Dubbed the sports cars of the bird world, goshawks are found across North America and in Europe, Australia, central and northern Asia, and parts of Africa. Its back is a uniform blue-gray; its underside appears pale gray from a distance. Hunting by stealth and surprise, a northern goshawk can burst into incredibly quick flight, twisting through branches and smashing through thickets in hot pursuit. It will persistently pursue a ruffed grouse for half a mile, emerging unscathed.
If an animal is on the ground, the bird sweeps down, delivering a crushing blow with its talons. Birds, squirrels, snowshoe hares, small rodents, snakes and insects are fair game to this agile hawk. Its Anglo-Saxon name, gos for geese and havoc for hawk, reflects its nature as a powerful predator. It sometimes shadows white-tailed deer, moose and black bear, red eyes watching intently, until a grouse or some other prey is flushed by the large mammals.
To accomplish the spectacular aerial feats for which they are renowned, northern goshawks possess large, robust bodies with rounded wingspans that, in females, can measure more than 1.2 metres across. Long tails act like rudders, enabling precise manoeuvres and dexterity. Females are larger than males, and tend to be the boss.
A winter flock of mourning doves often feeds and rests in a sheltered grove of oaks behind our house. Watching these doves and the northern goshawk provides fascinating insights about the interactions of species. In cold weather, the goshawk surprised and killed a less-alert or slower dove, plucking and eating it on the spot. The flock of doves returned and continued to forage on the ground within three metres of the feeding goshawk. Has a tacit understanding evolved between goshawks and doves that a kill means the others are safe?
A northern goshawk's nest used to be located in a thick forest of softwoods and hardwoods on property adjacent to our woodland. I had heard youngsters calling for parents, but mom and dad can be fierce protectors, so I left them alone. One year I found a dead juvenile in our woodland.
Four years later, while it was active, the nest was cut down in a clearcut operation. (Nova Scotia may rank goshawks as sensitive to human activities, but it rarely works the opposite way.) Late that summer, a new nest began to appear on our property, about 7.5 metres up in a red maple with forked branches to support it. I suspected the goshawks. Displaced birds of prey often construct a new nest for the next year. Barred owls have been nesting a short distance away for years, uprooted by the clearcut. How many wild animals could squeeze into our woodland sanctuary?
Northern goshawks are usually incubating two to four eggs by early to mid-April. While planting trees in the forest last May, I saw their aerial displays over the new nest site, a sure sign of a breeding territory. Later I saw the female in the nest. Soon the act of walking on the woodland road below prompted a warning cak-cak-cak, cak-cak-cak from the hillside. The calls became staccato and strident if I stopped. One day, while I was planting birches by the brook, the complainant materialized. With a scream that raged through the forest, she stormed across the path, folded her wings and dove straight for my head.
Reeling around, she came at me again. While the male protested from a distance, tree planting ended for that day. My wife, Alice, was chased home in a similar fashion. I never saw the youngsters, but I heard their calls.
When I worked as a regional biologist, I rescued juvenile goshawks that fell out of nests while chainsaws flattened the forest around them. The parents must have been overwhelmed-they offered no battle when I climbed to return their young.
As well as defending the young from intruders, females incubate the eggs. Males are tireless food suppliers. Each nestling requires more than 6.4 kilograms of food before it learns to fly.
Raccoons will sometimes climb a nest tree after dark to steal eggs or kill a young bird. Goshawks have excellent eyesight adapted for daylight, but they don't have good night vision.
Once the young leave the nest in July, the birds hunt a wider area, and adults no longer defend the nest.
Grouse and snowshoe hare populations dwindled around our home as the summer continued. The local nesting crows must have suffered at least one fatality by goshawk talons-the black entourage that follows the tractor when I mow fields in July was notably missing, although they had returned by late summer.
Last fall, Alice found feathers from a carcass along the trail not far from the two nests. A few feathers are hard to distinguish, and could belong to either a juvenile barred owl or goshawk. Both species begin nesting while snow is still on the ground-an abundance of winter, spring and summer food resources is necessary for both pairs to raise young successfully.
Besides restoring trees, our woodland activities are tailored to the habitat needs of deer, salamanders, frogs, trout, mink and otters. The northern goshawk is an exciting addition, but this spring I'll wear a hat!