Nature Discovery with Renée! It’s a Bird! It’s a Plane! It’s a…Bubo virginianus?!

Time for an adventure this week with Librarian Renée! Today’s Nature Discovery blog will feature an amazing animal that lives in our neighborhood!

All living organisms adapt to help them to survive and thrive in their environments. Whether it’s how desert plants store water or how humans are built to run for the hunt, adaptations are the processes that help organisms be better suited to their environment. A perfect example of an adaptation are eyes. Check out these two photos:

Notice how the mule deer’s eyes are on the side of its head and the mountain lions are in front (like ours!). You can tell if an animal is a predator or a prey by this handy rhyme, “Eyes on the side, I run and hide! Eyes in front, I like to hunt!” Eye position is an adaptation. Adaptations can be big or small, complex or simple. I think today’s animal has some of the coolest!!

Can you guess who I am?

  • I can see through the darkness with eyes so huge, they are fixed in their sockets and can not move.
  • Though my eyes can’t move, I see all around. My head rotates so I can track any sound.
  • Though my ears can’t be seen, I can hear my prey. I can hear a mouse in the grass 23 meters away!
  • I have no teeth, so I must swallow my food whole. It’s hard to digest the fur and bones of a mole!
  • Though my name says otherwise, those aren’t horns! They are tufts of feathers called Plumicorns!

Can I hear a HOOT HOOT if you guess a Great Horned Owl?!

Great Horned Owl (Bubo virginianus)

The Great Horned Owl is the most common owl found in our area, but as you can see from the above picture, while they are big (they can have a wingspan of close to 5 feet!), they can be hard to see. Their feathers resemble the bark of the trees in which they live. Now is the best time to see them, when the leaves of the trees haven’t fully filled in yet. If you are lucky you might even see a nest and some owlets. Great Horned Owls mate for life and do not typically make nests, but rather reuse the nest of another large bird. They nest in early winter and start incubating their eggs as early as February. In early spring, two to four very fluffy owlets will make their appearance (visitors along Coal Creek Trail have enjoyed watching a pair and their owlets this spring!). These babies will be ready to take a solo flight at eight weeks and will fully leave the nest by fall, using the summer months to perfect their hunting skills.

Great Horned Owlets

Great Horned Owls are very successful in our area because of the abundance of food. Their diet consists of mice, rabbits, prairie dogs, chickens, fish, Canada geese, cats, and even skunks. Like many owls, the Great Horned Owl is a nocturnal hunter, meaning it hunts mostly at night and it owes its success as a nighttime hunter to some clever adaptations. In the case of the Great Horned Owl, the eyes are its superpower!

Great Horned Owl Skull

Great Horned Owl eyes are at least as big as humans, which compared to it’s skull, are HUGE! Like most predators, the “eyes in front” gives the owl excellent depth perception, which is very important to judge distance of prey. The bony eye sockets act like a tube that directs the light onto the retina and helps to eliminate the scattering of light. These bony structures also help to support the size of the eye, but at a cost; an owl can’t move its eye in its socket. What’s the point of having fantastic vision if you can’t move your eyes?! Well, an owl doesn’t need to move its eyes because it can rotate its head almost completely around! Which brings me to the next amazing adaptation: its ears!

No, those feathers sticking out are not the owl’s ears. They are feathers called plumicorns, and scientists aren’t exactly sure of their purpose. If you could see a Great Horned Owl’s ears, you’d see they are not the same on each side of the head like ours, but are asymmetrical. One ear is higher on the skull then the other and the external structures differ as well. This helps the owl to finely tune sound. So as the owl turns its head, the different ear structures will pick up different sounds. When it has zeroed in on its food, the next adaptation – feathers – is fantastic!

Great Horned Owl (Bubo virginianus)

The feathers of the Great Horned Owl are truly remarkable. As I mentioned earlier, the owl’s feathers help them to blend in with their surroundings, or camouflage, which is very important for a hunter. Their feathers also help to keep them warm. The Great Horned Owl is completely covered in feathers, including their legs and feet. Being completely covered in feathers helps to keep the owl warm for nighttime hunting, but it also gives them stealth. Ever notice that your footsteps are muffled in socks? Owl feathers are specially designed to help muffle sound. Unlike other birds, owls have microscopic cross barbs at the end of their already fluffy feathers that make their feathers very flexible and full. In addition to helping owls from being heard, they also help the owl to hear! Those disc-shaped feathers around the eyes help focus sound waves to the ears. Camouflage, warmth, and stealth, while enhancing your hearing! Now that’s impressive.

The next time you head out for a walk, look for an owl! As the leaves fill in, they will be harder to find, so I suggest you search the ground. Since they swallow their food whole, owls will leave clumps of undigested food beneath their nest. These Owl Pellets will look like a 2-3 inch hairball containing bone fragments. A sure sign an owl lives nearby!

As the nights get warmer, take an evening stroll through your neighborhood. If you are lucky, you might feel a slight disturbance in the air followed by a shadow flying over your head and the landing of a large object on a street light. You are the one being watched!

In the meantime, check out one of my favorite picture books by Jane Yolen, Owl Moon, available as a downloadable audiobook. If you’d like to see a video of actual owlets as well as other bird of prey hatchlings born this spring, check out this YouTube video: Hatching Highlights.

Until next week, happy exploring!

-Renée

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