In this sixth part on the owls of Idaho, I’m getting down to species that I have seen much less often than those addressed in the first five parts. Next up for me is the northern saw-whet owl. I have mentioned a few times how rarely we see many species of owls despite their degree of abundance across the landscape. The Birds of Idaho Field Checklist classifies this owl as “common, but sometimes difficult to find.” Sometimes? Partners in Flight estimates that there are 2 million of these owls in the U.S. and Canada. I’ve seen maybe a dozen of them over 72 years. Maybe I’m just not very good at owl finding.
There are two other species of saw-whets. Or were. The Bermuda saw-whet owl was last seen in 1623 but is known from fossils and earlier reports. The unspotted saw-whet owl is a resident in the pine-oak forests of Chiapas, Guatemala, central Costa Rica, and northern Panama.
Like all small owls, I think adult saw-whets are incredibly cute. But if you see the juvenile birds, I swear you will want to take one home. But don’t do that. I bet you can get a plush version for your donation to some wildlife conservation organization.
Saw-whet owls get their name from the “skiew” or “ksew” or “skreigh-aw” call that is made when alarmed. According to many sources, this sounds like the whetting of a saw. Brewster (1925) writes, “Their general resemblance to the sounds produced by filing a large mill-saw was very close, I thought.” That’s of no use to most of us who have no idea what that sounds like, either. I can envision the mill, the saw blade, and stacks of logs in the snow. But the sound doesn’t come with it. Birds of the World describes it as, “… a harsh and startlingly loud staccato high-pitched bark … .” Adding some commas to that description won’t help either. I have tried to find a recording of this saw filing, without success. Please let me know if you find one.
Deer mice and white-footed mice are the most common prey, but shrews, house mice, harvest mice, and voles are also on the menu. During the breeding season males may bring more food than the female and/or young can eat. Extra mice are stored on branches or piled up in the nest cavity. Cannings (1993) once found 24 surplus prey items surrounding an incubating female. Adults will lay on mice that have frozen while stashed outside to thaw them before eating. I have submitted this idea to the website, “How Can I Improve My Relationship with Food?”
Next for me is the barn owl. This is one of the most widespread of all owls on the planet, being found over the entire Western Hemisphere except for most of Canada and the Amazon Basin. It’s also common in Europe, southern Africa, India, and Oceana. This huge range is the result of the species ability to use a wide variety of nest sites and prey items. Also important is that they use all sorts of human-modified habitats. Most of the barn owls I’ve seen were literally in barns or pole sheds or something similar. People I’ve met have said, hey, do you want to see my barn owls? Of course I do.
As a result of this distribution and its use of human-made structures, the barn owl is one of the most intensively studied owls, and perhaps one of the most intensely studied birds of any type. One thing we’ve learned is that the barn owl is more skilled at locating prey items by sound than any other animal so far tested. As a strictly nocturnal species, it has evolved superb hearing as well as exceptional vision in low light.
Because barn owls use nest boxes, they have been allies in rodent control for progressive farmers. One of the most famous ag projects was begun by ornithologist Yoshi Leshem in Israel in 1982. Leshem thought that because one barn owl can eat 6,000 rodents during a year, they might be able to help farmers eliminate the use of rodent poison. The National Barn Owl Project now monitors over 5,000 nest boxes in agricultural areas of Israel. The use of rodent poison has been greatly reduced, which has had numerous benefits for environmental health and saves the farmers money.
One other project closer to home is not so happy. Barn owls are among the most common victims of roadkill in Europe, Canada, and the U.S. Sadly, the world’s greatest known rate of highway mortality occurs right here in southern Idaho, along a 248-km stretch of I-84. Ornithologists in the Boise State University Department of Biology estimate that over 1,500 barn owls are killed every year along this highway.
Research has shown that there were more barn owls killed where the sagebrush has been replaced by cropland and dairy farms. So, while the human changes to the landscape have provided more habitat for these owls, those changes have also brought the owls into the danger zone of vehicular traffic. There were also some effects of landscape variables, such as distance to the Snake River. The conclusion of ornithologists working on this problem was that this population of barn owls cannot survive into the future without effective mitigation measures.
It may strike some as curious that the next owl on my list is the northern hawk owl. Again, this is not because of birds I’ve seen in Idaho. I’ve never seen one here, although there are around 20 records in eBird for the state. But I have seen them on three trips to Alaska — how many reasons do you need to go to Alaska?
I was also lucky enough to see a known nesting pair — at some distance — in northwestern Montana. Amazingly, on the trail into the hawk owl nest, we were greeted/blocked by a great gray owl sitting over the trail and only about 7 feet off the ground. This bird is normally worth a trip by itself! We couldn’t go around the owl due to the dense vegetation. So, we waited. Happily, the great gray flew off after about 15 minutes. You don’t usually want a great gray owl to leave. Funny about priorities.
The hawk owl is simply spectacular! It’s primarily diurnal, and gets its name from its long tail, which gives it a build more like an accipiter. Like several other species of birds, this owl occurs across the boreal forest of both hemispheres. Although it is a resident in these extensive forests, like the snowy owl it does move to more southerly latitudes in some winters.
In many raptors, the females are substantially bigger than the males. But in the northern hawk owl, this difference is minor. They also don’t have the asymmetrical ears found in many species that enhance the detection and location of sounds produced by small mammals. There are many different ways to be an owl.
Hawk owls feed primarily on small mammals during the summer but switch to species that don’t hide below the snow in winter. These include forest grouse, ptarmigan, and snowshoe hares. Fisher (1893) writes, “… when the snow is deep and its favorite food is hidden, it follows large flocks of ptarmigans and subsists on them.” These are big prey items for a bird of this size.
Their hunting strategies are also unusual for an owl. They can fly in low and fast, like a falcon, but also soar and hover. Seton (1890) writes, “In passing from one tree to another, it commonly throws itself headlong downwards nearly to the ground, along which it skims towards the next tree, and on nearing its goal rises with a graceful bound to the topmost perch offered.” This reminds me of the flight of a loggerhead shrike, jetting low to surprise any prey item that’s not paying attention. I’ve also seen prairie falcons use this strategy.
A final word on owl vocalizations. Note that despite the endless number of lame puns involving the purported “who” of owls, few species actually say, sing, or call, “who.” Saw-whets give a series of whistled “too” notes. Hawk owls sound similar only much faster — like a sped-up screech-owl. And the most common vocalization of the barn owl is a scream, much more like that of a red-tailed hawk.
Despite the stereotypes, what we see is that all owl species are different in some ways from all other owls. It’s the same for all birds — no two species are the same. Got to love diversity!