If you’ve passed through the forests of the southern Yukon at night in recent weeks, you may have heard the distinctive call of one of the territory’s smaller, wide-eyed avian residents as it tries to attract a mate.
“I’m not going to imitate it, but it’s usually described as a ‘tu-tu-tu-tu-tuuu,’ kind of (a) warm (sound that) carries, especially on a still night,” said Yukon Wildlife Viewing Program wildlife viewing technician Scott Cameron, describing the call of the Yukon’s bite-sized boreal owl.
Measuring under 30 centimetres from tail to beak, weighing between 90 to 200 grams and with a wingspan ranging from about 50 to 60 centimetres, the boreal owl is on the smaller end of the Yukon’s 10 recorded owl species and a rather elusive one, too. Luckily for budding ornithologists though, March happens to be the bird’s breeding season, which means they’re more vocal than usual.
Although one might typically associate bird song with warmer, spring weather — perhaps the pretty tunes of warblers, robins, or sparrows — boreal owls get started a little earlier, Cameron said, due to the fact that they’re a resident species that doesn’t migrate south for the winter.
But, like other birds, it’s the male owls that are doing all the work.
“It’s the males doing the calling and the females are hopefully responding, from the male’s perspective,” Cameron said. “The males are … trying to attract potential mates to nesting areas and that is cavities in old trees. They’ll often use an old woodpecker hole or a tree where the inner wood has rotted out a little bit, making a cavity or hole, and that’s where they like to raise their young.”
A female owl typically lays three to five eggs a season, and once a boreal owl finds a mate, it typically remains monogamous with both parents helping to feed and raise their young. However, according to some research, monogamy can change depending on how abundant food in a given year — basically, the less food available, the more faithful an owl stays.
“When there’s not a lot of food around, the theory is that the adults have to work harder to get food to feed the young, so they can’t be having multiple partners and multiple broods of young to take care of,” Cameron said. “But when food is super abundant, it’s easier to get and then perhaps you can support more than one family, so that’s one theory about how monogamous they are. Monogamy’s sort of a scale rather than an on-or-off, yes-or-no proposition as far as birds go.”
A typical boreal owl diet includes lots of small mammals like voles and mice which they like to hunt at night, swooping down from perches to grab the little critters with their claws. Like other raptors, they largely use sound, not sight, to locate their prey.
“The ear openings are asymmetrical, so they’re not at the same height of the face on either side of the head,” Cameron explained. “The idea there is that the sound from, say, a vole scurrying around, reaches the holes at slightly different times, and then the owl is able to get a better idea of the precise location based on just the slight difference in sounds arriving at its ear holes, so that’s an adaptation for hunting by sound and obviously at night or prey that’s under snow that you can’t see, you can see how that would be an advantage for the owl to get a lot of food.”
Boreal owls can also become food, too. Martens are known to prey on owlets and adult females at nesting sites and there are reports of great horned owls, red-tailed hawks and northern goshawks catching and eating adults, although it’s not known how common that kind of predation is.
Not to worry, though — boreal owls are considered a common species in the Yukon, and can also be found across North America from Alaska to Labrador as well as in Scandinavia and northern Russia.
But even with their abundance, actual sightings of a boreal owl are rare.
“Most reports are hearing the calling,” Cameron said. “Part of that is it’s secretive — it lives in forests, it comes out mostly at night, that’s when it does most of its calling, and it’s a small thing too.… It’s not like a great horned owl or a great grey, it’s a small little guy, so seeing one is certainly a treat.”
Should you be lucky enough to spot one, boreal owls are distinguished by their size (females are slightly larger) as well as brownish-grey plumage marked with white speckling on their heads and messy vertical streaks across their chests and bellies.
For his part, Cameron said in his five years as a wildlife viewing technician, he’s only seen them once.
“The one time I saw them was on a person’s property north of Whitehorse and he had an artificial nest box on a tree and he just invited me out to have a look and we saw the heads pop out,” he said. “It was pretty, pretty cute.”
Contact Jackie Hong at firstname.lastname@example.org