There has always been something about winter that reminds me of owls. Here in Minnesota, you can find owls all year round, but for some reason it's just not the same during the summer as it is in winter. Perhaps it's because they are easier to spot roosting in trees without leaves to obscure them. Or maybe it's their silent shadow soaring over sparkling snow in the light of the moon. And don't forget their alluring hooting calls that seem to resonate beautifully in the silence of winter, especially on a crisp, clear night. In the last blog post, I mentioned how this mild winter is likely benefiting our owl populations. Rodents are easier to catch without a deep subnivean layer. If you are ever lucky enough to catch sight of them mid-hunt you will be awe-struck, as they are well equipped for the task at hand (or should I say wing)! Owls are raptors, which are predatory birds that share certain characteristics. Minnesota raptors include hawks, eagles, owls, falcons, and osprey. Raptors are identified by the first three characteristics below, but owls have an additional two that aid them in their superior hunting capabilities.
1. All raptors have a sharp, hooked beak used for tearing food into smaller pieces. The bald eagle (left) has the most impressive beak of all the raptors. Beaks differ from species to species, specialized depending on their type of prey. Owls have smaller beaks than other raptors because they typically swallow their prey whole, eliminating the need for a large tool to help tear it into smaller pieces.
2. All raptors also have very strong and very sharp talons, aiding them in catching prey. Raptors have a unique locking system in their feet, allowing them to tightly grip their prey or a tree branch without continually contracting their muscles. This means they don't have to worry about getting tired and letting go! Owls, like ospreys, have two toes facing forward, one toe facing backwards, and one that can swivel back and forth (right). This allows them to have incredible gripping strength in their feet, often squeezing their prey to death. Owls, unlike other raptors, have feather-covered feet which are thought to help retain heat and protect their feet from the bites/scratches of feisty prey.
3. All raptors have incredible eyesight. In fact, eagles are said to have the best eyesight in the animal kingdom. Raptors, except owls, hunt for their prey from high up in the air, requiring the ability to see very small prey from very large distances. Owls typically hunt for their prey from the branch of a tree, so they do not need to see as far. Many of them, however, are nocturnal and need to catchy prey in the dark! So owls have magnificent night vision. In proportion to the size of their head, owls have very large eyes. If our eyes were the same proportion, they would be the size of softballs! Large eyes = large pupils = more light entering the eye. They use light very efficiently due to the high ratio of rods to cones. Rods are specialized cells that aid in the ability to see in black and white (night) and cones in color (day). If you lit a single candle in the use-to-be Metrodome, an owl would be able to clearly see a mouse scampering about on the field. Incredible, right!? One other thing: owls' eyes are fixed in their sockets by a boney sclerotic ring (above left), meaning they can't look from side to side without moving their entire head. To make up for that, they can rotate their heads much further than ours, an incredible 270°! (Not 360°, a common misconception).
4. Now on to what really makes owls unique. They have the capability of silent flight! All feathers have a central shaft, which has many barbs coming off of it. Each barb has many more barbules, and each barbule has hooks on it that essentially work like Velcro. They hook together, allowing you to "zip" up a feather with your fingers. Owl feathers are different in that towards the edge of their feathers, they have fewer barbules and hooks than the feathers of other birds, so they don't lock together as tightly. This allows air to move through the feather and causes less resistance in flight. With less resistance, their wings make less noise, allowing them to sneak up on prey!
5. The last, awesome thing about owls is their sensational hearing. Owls have asymmetrical ear placement, meaning one of their ears is located higher on their head than the other. This gives owls the capability of hearing sounds at different volumes and angles, allowing them to pinpoint where sounds are coming from! In addition, owls' big, round faces act as a satellite dish (like our external ear) helping to catch sound and funnel it in towards the owls' ears. They can hear so well, that they can hear mice moving around underneath deep snow! Watch this Great Gray owl use sound to catch a lemming!
So who are the prey they are hunting? For most owls, 90% of their diet consists of mice, voles, squirrels and other small mammals. Depending on the species, they may also eat insects, frogs, fish, crayfish, larger mammals and rodents, birds, and even other owls! But owls cannot digest fur, bones, scales, claws, teeth, or feathers so these parts of their prey are regurgitated in the form of a pellet. You can find these pellets under the owls' favorite roosting locations in the woods around your house. They're a good reminder of the nocturnal battles that occur while we sleep. Below is a pellet from a barred owl I've seen around the HUG Campus. Inside we found four skulls! Proof our owls aren't going hungry this winter!
So whooooo should you be on the lookout for in our woods?
Barred Owls are the most commonly seen type of owl around here. They are the only owls with dark eyes (all others have yellow eyes) and can be identified by the vertical stripes (bars) on their chest. They are best known for their "who cooks for you, who cooks for you all" call heard around dusk and later in the night.
Great Horned Owls can be found all over our state. They are known by their large size and ear tufts, and are nicknamed the "tiger with wings". Great horned owls have been known to eat animals as large as skunks, other owls (like the barred owl), and consume an estimated 4,000 mice every year! Talk about pest control! They are the earliest nesters of owl species, nesting in late January and early February, so now is the perfect time to hear their loud, booming call. You can watch a mom sit on her eggs on this owl cam!
Northern Saw-Whet Owls are also common in this area, but this tiny owl can be hard to find! It is only 7-8" tall and is found in conifer forests and cedar swamps, where it can be difficult to locate among the dense evergreens. Some of these owls migrate, but many stay in Minnesota all winter.
This year, you may be lucky enough to see a Snowy Owl. This is what they call an irruption year, which means that overpopulation, a scarcity of food, or poor hunting conditions have caused many snowy owls to venture south past their normal ranges. You can track sightings of these birds on this website if you are looking to add it to your life list. The owl below has been seen numerous times around the Brainerd fairgrounds/industrial park area. Quick! Find one before they head north for breeding season!
Minnesota is home to 8 other species of owls, but unfortunately, they are not commonly seen in our area. January is a fantastic month to get outdoors for a night hike! Bring your kids! Check out the book Owl Moon by Jane Yolen (a childhood favorite of mine) to get them excited! Allow the light of a full moon to guide you through the glistening winter woods, and keep your ears pricked for the soft, hooting call of our nocturnal warriors. As always, enjoy!