Strigidae

Owls are amazing birds.

They live on almost every land. Some are tiny. Other owls are very big.

Most owls have large heads. They also have round faces. This helps them hear well. They can find food by sound.

Owls fly very quietly. Their soft feathers stop noise. This lets them sneak up on prey. They can hunt without being heard.

An owl can turn its head a lot. It can turn its head very far. This helps it see around.

Many owls sleep during the day. They stay very still in trees. This helps them stay hidden. It is a clever way to rest.

True owls belong to a large family called Strigidae.

There are 230 species in this family. They live on every continent except Antarctica. Some owls are very small, like the elf owl. Other owls are very big, like the Blakiston's fish owl.

Most owls fly in a very quiet way. They have special feathers that stop noise. These feathers work like a soft carpet on their wings. This silent flight helps them sneak up on prey.

Owls also have amazing hearing. Their ears are not the same on both sides. This is called asymmetrical ears. This helps them find where a sound comes from. If a mouse squeaks to the left, the sound hits the left ear first. The owl's brain then turns its head to face the mouse.

An owl can turn its head very far. They can turn their heads 270 degrees. This is possible because of how their blood moves. They have a large artery, called the vertebral artery, that feeds the brain. It stays safe even when the neck twists.

True owls belong to a large family called Strigidae.

This group includes about 230 living or recently extinct species. They live all over the world on every continent except Antarctica. These owls come in many different sizes. The tiny elf owl is very small. The Eurasian eagle-owl and Blakiston's fish owl are huge by comparison.

Most owls have large heads and short tails. They also have round facial discs around their eyes.

Owls are famous for their silent flight. This helps them hunt without being heard. Their wings have three special features to stop noise. First, there is a comb of stiff feathers on the front edge. Second, the back edge has a flexible fringe. Finally, the tops of their wings have soft, downy material.

This feels like a soft carpet. These parts work together to reduce the noise made by flapping or gliding.

Owls use their amazing hearing to find food. Their ears are asymmetrical, which means they are not the same on both sides. This helps them find exactly where a sound comes from. If a mouse squeaks, the sound might hit one ear before the other. The owl's brain uses this timing to find the prey.

They can then turn their heads to face the sound. Their facial discs even help deliver more sound to their ears.

An owl can turn its head up to 270 degrees. This is a huge movement for any animal. They can do this without hurting the blood flow to their brains. They have a large artery called the vertebral artery. This artery passes through bony holes in their neck bones. These holes are ten times larger than the artery itself.

This extra space acts like an air pocket for the artery to move safely. Small connections also allow blood to flow through different paths.

Scientists have studied these birds for a long time. A zoologist named William Elford Leach introduced the family name in 1819. More recently, researchers like Jessie Salter studied their DNA in 2020. This helped scientists understand how different owl groups are related. Some owls even have special pigments called porphyrins in their feathers. These pigments glow under UV light. This helps biologists see how old the feathers are.

The family Strigidae contains the true owls, often called typical owls.

This massive group includes 230 living or recently extinct species. They are spread across the entire world, appearing on every continent except Antarctica. Within this family, sizes vary drastically. The tiny elf owl is only a hundredth the size of the largest species. These giants include the Eurasian eagle-owl and Blakiston's fish owl.

Despite these size differences, most owls share a very similar body plan. They typically possess large heads, short tails, and cryptic plumage for camouflage. Most species are arboreal, meaning they live in trees, though the burrowing owl is an exception.

Owls are masters of silent flight, which allows them to hunt prey without being detected.

This ability comes from three specific physical adaptations in their wings. First, a comb of stiff feathers sits on the leading edge of the wing. Second, the trailing edge contains a flexible fringe of feathers. Third, the tops of the wings are covered in downy material. This downy texture is similar to a soft carpet. Together, these features create significant aerodynamic noise reductions during takeoff, flapping, and gliding.

To find prey, owls rely on highly sensitive hearing and massive eyes. Their ears are asymmetrical, meaning they are positioned differently on each side of the head. This asymmetry helps the owl localize sounds in multiple directions. The feathers of the facial disc are arranged specifically to increase the amount of sound delivered to the ears. If a mouse squeaks, the owl computes the timing of the sound. If the sound reaches the left ear first, the owl knows the prey is to its left. The brain then directs the head to face the target.

One of the most remarkable traits of an owl is its ability to rotate its head. An owl can turn its head up to 270 degrees in either direction. This movement does not damage blood vessels or disrupt blood flow to the brain. Scientists have identified four major biological adaptations that make this possible. A major artery, the vertebral artery, feeds the brain through bony holes in the vertebrae. These holes are ten times larger in diameter than the artery itself. This extra space creates air pockets that allow the artery to move during twisting. Additionally, small vessel connections between the carotid and vertebral arteries allow for uninterrupted blood circulation.

Some owl species also possess unique pigments called porphyrins in their plumage. Porphyrins are a group of nitrogen-containing pigments, similar to chlorophyll or heme in blood. While other birds use these pigments for eggshells, owls use them in their feathers. These pigments are most common in new feathers but are easily destroyed by sunlight. Interestingly, porphyrins fluoresce under UV light. Biologists use this fluorescence to determine the age of an owl. By using black light to check the intensity of the glow, researchers can distinguish between different generations of feathers.

The study of Strigidae has evolved significantly over time. The family was first introduced by the English zoologist William Elford Leach in 1819. He was the Keeper of Zoology at the British Museum at that time. More recently, a 2020 molecular phylogenetic study by Jessie Salter and collaborators changed our understanding. This study used DNA to show that the family is divided into two sister clades. It also revealed that some traditional genera were paraphyletic, meaning they did not include all descendants of a common ancestor. These findings led researchers like Frank Gill and Pamela Rasmussen to update the official lists of world birds.

Environmental changes and competition also impact these birds. In North America, the barred owl is an invasive species that competes with the northern spotted owl. This competition occurs because both species rely on mature forests of old, tall trees. Deforestation from overlogging and forest fires has reduced the available habitat. As barred owls encroach on these territories, the spotted owl population has declined. This loss could cause a trophic cascade, which is a disruption in the healthy ecosystem. Protecting the mosaic of habitats created by natural, low-severity fires is vital for their survival.