Wisconsin Natural Resources magazine

Wisconsin Natural Resources magazine

Two adult Saw-whet owls. © Herbert Lange

Saw-whet owls can weigh between 1.9 and 5.3 ounces and are close to the size of an American robin.
© Herbert Lange

October 2013

Whooo's in my woods?

Meet Wisconsin's tiniest owl, the northern saw-whet.

Dave Wilson

The first time I heard the sound I thought, "Who is out in the woods at this time of night, this time of year and this close to my cabin tooting on a whistle?"

It was 10 p.m. and early spring. There was still snow on the ground. The sound was something like a short continuous toot on a whistle.

I had a hunch it was an owl, but figured that owls hoot; they donít toot. I finally contacted the area biologist at the DNR office in Park Falls who recommended that I contact Christian Cold, local raptor specialist, wildlife technician and educator at the DNR office in Ladysmith. After describing the sound to him, Cold knew the answer to my question.

"Thatís a saw-whet owl," Cold assured me. He noted that he had recently been taking people on tours at night to listen to the owl.

Coldís answer, though, just raised so many more questions for me. What do they look like? Why havenít I ever seen one?

The northern saw–whet owl (Aegolius acadicus) is Wisconsinís tiniest owl. It is a nocturnal powerful ball of fluff packaged in a body the size of a robin. And while you may be lucky enough to hear one making a series of whistled toots in the spring, they are rarely seen.

These woodland wee–ones live in tree cavities. Some are permanent residents, while others may migrate south in winter or move down from higher elevations. Their range covers most of North America.

According to legend, John James Audubon named this bird the saw-whet owl because its "skiew" call resembled the sound of whetting (sharpening) a saw. The saw blade is put on a flat surface and a whetstone (sharpening stone) is drawn the length of the blade across the teeth of the saw to remove the burrs and to make the width of the teeth uniform after sharpening. The whetstone drawn across the teeth makes the "skiew" sound when done rapidly.

The saw-whet owl only vocalizes during its breeding season, which is March through April. I have tried several times to get close enough to the calling owl in the spring to get a look at one, but I have not had any luck.

During the summer, while the owl shares the woods with me, it is mostly silent as it watches and waits for prey — or to make sure it doesnít become prey.

Saw–whet owl in conifer tree branch © Brian Rudinsky/U.S. Fish and Wildlife Service
The northern saw–whet owl's defense upon discovery is to sit still and not fly, leading people to perceive them as "tame."
© Brian Rudinsky / U.S. Fish and Wildlife Service

"Their favorite habitat is newer, mixed forests which contain evergreens," Cold says. "They also seem to prefer water nearby. Saw-whets tend to avoid mature or open forests with larger trees, perhaps because larger owls like barred owls and great horned owls will eat them."

The secretive saw-whet depends on its plumage for camouflage. If it is startled it will flatten itself along a branch so as to appear like part of the tree.

Females are slightly larger than males. The saw–whet is short–bodied with a short tail. Its head looks overly large and it has no ear tufts. Their bright yellow eyes appear large, centered in a facial disk that has white and brown radial streaks on the outer edge and white only in the center. The rest of the head is brown or grayish brown and their plumage is fluffy and streaked brown and white.

Saw-whets do not make nests like other birds. Instead, they have their young in holes in trees made by other birds.

Cold says saw–whet owls prefer to dine on mice, voles, shrews and large insects in the warmer months.

"A few may remain year—round in this area, but harsh winters like the last one took its toll on many birds," Cold says. "Cold temperatures and deep snow are hard on them as they cannot plunge into deep snow to catch their prey."

Most Wisconsin saw-whet owls migrate in the spring and the fall. Their seasonal "movements" occur on a broad — front, where scattered birds move through our lawns and neighborhoods at night mostly unnoticed.

Larger groups migrate in the fall because their young are with them. Smaller groups migrate in the spring because they are the winter survivors. Saw-whets migrate as far north as mid–Canada and as far south as the Gulf of Mexico.

Like the howling of the wolf, the call of the loon and the gurgling of a raven, the distinctive "toot" of the saw–whet owl makes Northern Wisconsin wild and intriguing.

Cool facts from the Cornell Lab of Ornthology:
  • The main prey of the northern saw-whet owl are mice, especially deer mice of the genus Peromyscus. Adult mice are usually eaten in pieces in two different meals. One owl was found dead after apparently trying to swallow a large mouse whole.
  • The female northern saw-whet owl does the incubation and brooding. The male brings her all her food while she is incubating. She leaves the eggs for only one or two short trips each night to defecate and to cough up a pellet.
  • While the female saw-whet broods her nestlings, she keeps the nest cavity very clean. When the young are about 18 days old, she starts spending the night in another hole, and then the dirt starts to accumulate. When the young owls leave the nest after another 10 days to two weeks, the nest cavity has a thick layer of feces, pellets and rotting prey parts.
  • To hear the saw-whet visit the Cornell Lab of Ornithology online at All About Birds Northern Saw-whet Owl

Dave Wilson lives off the grid in a log cabin he built on the South Fork of the Flambeau River.