NATIONAL PARK SERVICE Wildlife Portfolio of the Western National Parks

THE AMERICAN HAWK OWL is a dweller of the spruce woods rather than the open, treeless plains. Its medium size (total length, 15 inches), long tail and slender body give this bird a decided hawklike appearance. Its rapid wing-beats, direct flight, and habit of perching in the open on the top of some dead tree correspond with the actions of the common butcher bird or shrike, which it resembles in many ways.

In the far North many species of owls have to hunt by day as well as by night. This is particularly true of the American hawk owl. On June 8, 1926, a companion and I found a hawk owlet sitting quietly on the forest floor. Apparently it had fallen from its nest. We took it back to camp, where we raised it on mice which were abundant and easy to trap. Experiments proved that this young owl could see just as well during the day as at night. Whenever we made a slight noise, similar to a mouse scratching, the owlet was all attention (see illustration), but if a violent noise was made close to the bird it shook its head, seemingly in distress.

The call note of this owl is a long drawn-out screech with a sharply accentuated high-pitched ending, "all-l-l-right!" Whenever we gave a good imitation of this "liaison" call, we found that any hawk owl in the neighborhood would respond and it frequently came directly to the spot where we gave the call. By following the owls, it was discovered that this distinctive call is the method used by members of an owl family to keep track of each other when hunting in the forest.

The number of hawk owls in a given area seemingly is closely related to the abundance of mice in the same area. In June 1926, at Savage River, Mount McKinley National Park, I found these owls so numerous that 39 were counted in 2 days. Field mice and varying hares were also abundant at that time in the spruce woods inhabited by the owls. Six years later I again visited this identical area and, although I hunted all summer for these birds, I did not find even one. During my second visit I found that both field mice and varying hares also were absent from this area. It is believed that the absence of these rodents, which are the owl's chief food supply, was the real cause for the lack of owls.

PHOTOGRAPH, SAVAGE RIVER, MOUNT MCKINLEY NATIONAL PARK, JUNE 13, 1926. COURTESY OF MUSEUM OF VERTEBRATE ZOOLOGY.