Night Moves
Learn how owls use their impressive adaptations after dark.
Whether in a patch of dense woods or in a suburban yard, owls use their unique and spectacular abilities to master their environment. And all their senses come together to help them thrive when most animals are sound asleep.
What a Sight
Take one look at an owl and you can see why vision is one of its sharpest senses.
“They have large eyes for their body,” says Lori Arent, assistant director of the Raptor Center at the University of Minnesota. “They take up something like 3% of their body weight. For humans, it’s far less than 1%.”
Their peepers are so large that they’re fixed in the eye sockets for support, so owls can’t move their eyes more than a degree or two. To compensate for that limited eye motion, owls are able to turn their heads 270 degrees.
And owls see a different range of colors than other birds, or even people. They have an abundance of receptors in their eyes called rods, which help pick up light levels, and fewer cones, which are used to detect colors. The trade-off allows them to see prey and avoid obstacles in the dark.
Stealth Mode
These nocturnal fliers have two advantages in low light: They have excellent skills and adaptations to hear rustling leaves and snapping twigs, and they have the ability to fly almost without making a sound.
Listening plays a huge part in hunting. Owls bob their heads up and down while trying to hear, in a behavior called triangulation. The goal is to change the location of their ears to home in on where the sound is coming from. To make the
process easier, several species even have one ear that sits higher than the other.
“Owls that hunt in the depths of darkness, not just dawn or dusk, rely even more on their hearing,” Lori says. “Having asymmetric ears helps them localize the sound, at least vertically.”
Once they’re ready to swoop in, they do so with very little noise. Their wings are lined with fine, comblike fringes that dampen the flapping sound most birds’ wings make, letting them glide silently.
Nose Blind
Most birds have a poorly developed sense of taste and smell, and the same is true for owls. While it may seem like a big disadvantage for a predator to not have a tuned-up sniffer, great horned owls benefit from their dulled sense.
“There are not a ton of sensory receptors in great horned owls’ nasal passages,” Lori says. “Which is good, considering they’re the primary predators of skunks!”
Large owls have a taste strictly for meat and dine on a variety of animals, from small rodents like mice and rabbits to birds as large as ptarmigans. But fledglings, which are still learning how to use their impressive abilities, start smaller.
“Young birds do not have the skills to catch small rodents yet,” Lori says, “so a lot of them start by going after bugs.”
Get a Grip
Once owls lock their eyes (or ears) on prey, one last fantastic asset comes into play: Unlike most hawks and eagles, owls have a fourth opposable toe. Its range of motion is similar to that of a human thumb, as it can move to the front or back of the foot to help owls snatch a field mouse, perch on a limb or move within their nests.