What is an Owl?
Owls are birds of prey or "raptors." A raptor is a bird that has a sharp beak and sharp claws (talons) that it uses to catch and eat its food. Check out our Birds of Prey website for more information!
Members of the raptor group include hawks, eagles, falcons and owls. Unlike other raptors, owls are mostly nocturnal, hunting at night when the other raptors are sleeping. Because of this, owls and other raptors can share a territory and tend to not compete with each other.
An example of this would be a red-tailed hawk and a great horned owl. During the day while the owl snoozes, the red-tailed hawk will be able to find prey that is also active in the daytime. But at night, the owl takes over, hunting nocturnal animals.
As a group of birds, owls have been around for a long time. Owl fossils have been found that are 70 - 80 million years old. Today, members of the owl family can be found on every continent except Antarctica! Scientists believe that almost 155 different kinds of owls live throughout the world. In North America, 19 different kinds of owls can be found. A group of owls is called a parliament.
Twelve different species of owl have been found nesting in Idaho. The presence of a nest means that the birds are residents and not just visitors. It is possible that some visiting owl species might start nesting here, so reporting rare owl sightings is important.
Idaho's largest owl by height is the great gray owl. If you put Idaho's owls on a scale, the great horned owl is the heaviest. Our smallest owl is the appropriately named pygmy owl.
Resident Idaho Owls
When we think of owls, we think of being active at night. But even among the owls, enjoying the nightlife does not always mean the same thing. Several of Idaho's owls are strictly nocturnal. The barn owl and long-eared owl become active only after dark. Burrowing owls and pygmy owls are more likely to be active during the day or diurnal. And the great horned owl is "crepuscular". This means that it is most active at dawn and dusk.
So, why are these owls out at different times of night? Because many owls share habitats, being active at different parts of the night might help reduce competition between the different kinds of owls. In addition, different prey species are also active at different times of night. Owls need to be able to hunt at the same time that their food is active to make sure that they get dinner!
How Big are They?
Owls can be very small like the 5-inch elf owl or pretty big like the 2-foot tall great gray owl. Whether large or small, they all look stocky with large heads and soft feathers.
Unlike most raptors, many owls have feathers on their legs and toes. Owls have large eyes that face forward as do your eyes. Around the eyes are the facial disks that give the owl a "face." Their wings are long and broad and their tails are usually short.
Most owls do not make long migrations. They usually live in the same place all year long. One exception is the insect-eating flammulated owl. These owls migrate south each fall to find the insects they need to survive.
Sometimes, owls are forced to move because their prey becomes scarce. When this happens over a large area, many owls may leave their home territory and travel far to find food. This is called an "irruption" and it can be very spectacular as thousands of owls move into an area to find food.
Such an irruption of owls happened several winters ago in Minnesota. Birdwatchers all over the state were thrilled with sightings of several owl species rare to Minnesota. Residents of western mountain towns are sometimes treated to mini-irruptions of their own as owls living at higher elevations move down in elevation to find food during harsh winters.
Eye See You!
Owl eyes are one of this raptor's most amazing adaptations. Their eyes allow them to navigate through their habitat in the dark. Owls that hunt during the daytime use their eyesight to find food. And owl eyes are one of the things we notice most about these birds.
Owl eyes are very large. They are so large that they cannot move in their sockets. You can roll your eyes, but not an owl. Owls also have a smaller visual field than you do.
To see what your visual field looks like try this experiment. Hold your arms out with both of your index fingers in front of your nose. While you stare straight ahead, move your arms in an arc toward your sides. When you can no longer see your fingers stop moving your arms. The arc that your arms made is your visual field and measures approximately 180 degrees. An owl's visual field is about 110 degrees. For an owl to focus well, it must turn its head to get an object into its visual field. In addition, owls often bob their heads up and down to judge distance.
Seeing well in the dark is the major function of an owl's eyes. The size of an owl's eyes is very important for seeing at night. Because the eyes are so large, they have a large surface area to collect light. The light hits specialized cells in the eye that help animals see in low light levels. These cells are called rod cells. Owls have many more rod cells than other animals.
In addition, owls have a structure called the "tapetum lucidum" at the back of each eye. Light goes into the owl's eyes and hits the rod cells. It then bounces off the tapetum lucidum to hit the rod cells again. This lets the owl see the light two times instead of just once. And for an owl, this turns the night into day.
You can see the tapetum lucidum when you shine a light at an animal at night. That glowing yellow or green eyeshine you see is actually the tapeta bouncing the light back into the eye. These structures, along with a large surface area and high numbers of rods, work together to give owls exceptional night vision. As a matter of fact, an owl can see three times better in the dark than you can. Check out this demo of how the nictitating membrane works (second eyelid.)
The Better to Hear You
Because owls have such big eyes and good vision, we tend to think that they hunt by sight. Amazingly, owls hunt mainly by sound. Could you find your dinner by listening for it?
The first thing you need to know about owl ears is that they are not on the top of the owl's head. Those "ears" you seen on a number of species are feathers called "ear-tufts" and they have nothing to do with hearing. There are several things that work together to give owls excellent hearing.
The first are the facial discs. These discs surround the owl's face and give the bird its distinctive look. Made of several kinds of specialized feathers, the facial discs collect sound around the owl's head, just like a satellite dish collects signals for your television.
Another neat adaptation owls have is asymmetrical ear placement. This means that owl ears are not directly across from one another on the bird's head.
If you put your fingers in your ears and look in a mirror, your fingers will both be at the same height. If an owl put its talons in its ears, one talon would be higher on its head than the other talon. Having asymmetrical ear placement means that sounds reach the owl's ears at different times.
As the owl lowers or raises its head, it can position its head so the sound reaches both ears at the same time. When this happens, it means that the source of the sound is directly in-line with the owl's face. Some species of owl also have a moveable ear flap that they can use to increase or decrease the sound coming to their ears.
So, how well can owls hear? Have you ever heard the saying "you can hear a pin drop?" Well, an owl probably can! A great gray owl sitting on a fencepost 60 feet away can locate a vole running in a tunnel under 18 inches of snow. A barn owl can capture prey when blindfolded. However, they cannot capture prey if one of their ears is plugged or if they lose their facial disc feathers. For owls, when it comes to finding food, listening is definitely better than looking.
What's For Dinner?
Owls are predators. They eat many different kinds of prey depending upon their own size. Small owls such as Pygmy owls and saw-whet owls are small so they usually hunt for large insects and small rodents like shrews and mice.
Owls pretty much eat whatever they can get their talons on. But the most common prey animals are the small rodents such as mice and voles. These little mammals are important food sources for many animals. They can also be serious pests for people.
Larger owls also capture bigger prey like voles, woodrats, rabbits and squirrels. Great horned owls will even catch and eat skunks-----yuck! Other prey includes scorpions, lizards, snakes, frogs, toads, birds, bats and even fish.
How Much Do they Eat?
Farmers can lose huge amounts of crops and stored grains to rodents. Lost crops means lost money for the farmer. Owls play an important role in keeping these potential pests under control. And they do it all for free!
If you do the math, you will find that one barn owl needs to eat about 79 pounds of mice a year. During its 10 year lifespan, that turns out to be around 798 pounds of mice. Which is about 12,775 individual mice!
Each of these mice needs to eat approximately 10% of its body weight each day. And 12,775 mice will eat almost 31,000 pounds (15 tons) of food each year. Wouldn't you like to have a few barn owls living on your farm?
Do the Math!
The average lifespan of a barn owl is 10 years.
A barn owl needs to eat 3-4 ounces of food a day and the average weight of a mouse is 1 ounce.
Scientists determined these figures by studying barn owls and their prey. One thing they relied upon to find out what the owls were eating was owl pellets.
Pellets are the non-digestible parts of an owl's meal; the hair, feathers, scales and bones of their prey. Pellets are formed in the gizzard and then spit up 6 - 12 hours after the owl has eaten.
Scientists collect the pellets and pull them apart to see what they contain. This may sound gross, but it is a fascinating way to look at an owl's diet (and it is pretty cool!) It is also an accurate way to count how many prey animals the bird ate. Owl pellets are a lot of fun to dissect. See if you can talk your teacher into doing an owl pellet dissection in class!
Owls are pretty content just to hang out. They are not very active birds unless they are hunting or feeding young. But they do have some interesting behaviors. If a snoozing owl is disturbed during the day, it will often do its best to pretend it is part of the tree in which it is roosting. This is called the "erect posture". Owls exhibiting this posture stretch themselves as tall as they can with their ear tufts standing straight up. They will also close their eyes until they are only slits. Standing perfectly still, they blend almost completely into the branches fooling possible enemies.
Another interesting posture owls use is a defensive posture. This is most often used by young owls that are not yet ready to fly. When threatened the owl will fluff up its feathers making it look twice as big.
To further increase its size, the bird will raise its wings over its back like a large fan and spread its tail feathers. Add some hissing and bill clacking and a young owl can look like a pretty scary critter. Most potential enemies find this posture very convincing and quickly leave the young owl alone. Adult birds will sometimes use a defensive posture, especially if the bird is injured and on the ground.
A number of owl species are well known for their defense of their nest and young. Great horned owls, in particular, have a reputation for being very fierce when defending their youngsters. The adults will dive bomb intruders hitting them with their talons and feet. Scientists studying these large owls are very careful when they are doing anything around an active great horned owl nest.
Nesting and Reproduction
We mostly notice owls when we hear them. And they are the most vocal during the nesting season. Owls call to establish their territory and attract a mate. Owl calls vary depending upon the species. In general, large owls make lower calls than smaller owls and males have lower pitched calls than females. If you have a pair of great horned owls in your neighborhood, listen to them and see if you can tell the male from the female.
Along with calling, many owls use flight displays during courtship. Once the pair has mated, they begin to look for a good nest site. Owls do not build their own nest. Some species use old hawk, crow or raven nests. A few others use a scrape on the ground and a number of small owls nest in tree cavities or nest boxes.
Incubation begins when the first round white egg is laid. During incubation, the male will feed the female and both parents take care of the nestlings. Most owl species lay 2 - 7 eggs that hatch in about 3 - 4 weeks. Young owls leave the nest from 27 -70 days after hatching with the larger owls staying in the nest longer.
Some of the tree-nesting owlets do something called "branching" in which they climb around on tree trunks and branches before they can fly. Owlets stay with their parents for most of the summer before finding a territory of their own.
Because owls are nocturnal, observing them can be challenging. Begin your study of owls by spending time looking at the owl section of a field guide to birds. This will help you learn to tell one species from another. A field guide can also help you learn about the kinds of habitats different owls prefer as well as their different calls.
Contact your regional Fish and Game office to learn about bird watching groups such as Audubon clubs that are active in your area. Sometimes these groups plan nighttime field trips to go "owling" and this is a great way to learn.
If you have a pair of owls in your neighborhood, listen to them at night to learn their calls. By moving quietly, you can sometimes get close enough to see the birds. Even though it is dark, use binoculars so you do not disturb the birds. On camping trips, take some time at night for quiet listening to see if any owls are calling. And visit places where some of our daytime owls like the burrowing owl live. Observing owls can be challenging and fun. Plus, you might get to stay up late!
Owls in Myth and Legend
From ancient times to the present, owls appear in tales from many different cultures. Both the Greek and Roman goddesses of wisdom, Pallas Athene and Minerva were often pictured in the company of an owl. Owls in China were associated with thunder and lightning. Long ago in Europe, a dead owl was thought to ward away lightning, hail and disease.
Other cultures associated owls with death in both good and bad ways. Some North American Indian tribes considered owls to be an omen of death. Other tribes thought owls were soul-bearers that transported the spirits of the dead to the afterlife. This belief could also be found in some ancient oriental cultures. Members of the Hidatsa people of the Dakota tribe called owl the "keeper of game spirit" that watched over the bison herds. The burrowing owl was considered to be the protector spirit of warriors of this tribe.
Nowadays, we see owls in movies such as "Hoot" and read about them in books. The "Wise Old Owl" appears in many children's stories. The owls of Harry Potter deliver mail while the owl of Winnie-the-Pooh gives advice. The children's book series Guardians of Ga'hoole featuring owls is quite popular with upper elementary readers. Many younger readers learn about great horned owls in Owl Moon. If you look around you, you might be surprised at how many owls you can find!