Thursday, January 31, 2013

Zoo Presentation Part 3: The Spectacled Owl


If you're still with me, thanks for hanging in there! On Tuesday I posted my presentation on the black-tailed prairie dog. Yesterday we looked at the giant Pacific octopus. In today's concluding segment, the animal at hand is the spectacled owl.



Juvenile spectacled owl in flight
Have you ever tried to sneak up on someone without them hearing you? Did it work? Have you ever tried to do it going as fast as you can? Not so easy, right? It would be much easier if you were an owl!

These are spectacled owls, mainly found in Central and South America, most often in rainforests. They have very broad wings and soft plumage which enables them to fly virtually soundlessly through the air. Their flight feathers have comb-like “fingers” which help to deaden the sound of their flight. This is very important to the owl in two ways: the first way is so that their prey will not hear them coming. Can anyone think of a second reason? It’s so the owl can hear their prey moving about even while they are flying so they can pinpoint its exact location.

Owls have an excellent sense of hearing. Their ears are recessed behind their facial disks and sound is directed into them by short, stiff feathers on the outside. Ever if there is no available light an owl would still be able to hunt using only its sense of hearing. Have you ever seen an owl bob and cock its head at different angles? When it does that it’s trying to pinpoint the source of a sound it finds interesting or important. 

Great horned owl skull
But hearing is not the only outstanding sense an owl has. When you see an owl what is usually the very first thing you notice about them? Their eyes! Owls have enormous eyes relative to their skulls and this gives them an amazing sense of sight. Here is the skull of a different species of owl—the great horned owl—but it’s very similar to the skull of a spectacled owl. Notice how huge the eye cavities are. Because their eyes take up so much of their skulls there is no room left for muscles to roll them around. So owls cannot move their eyes; they are fixed and always point straight ahead. So, how do they look around? By turning their heads. Owls can turn their heads 135 degrees in either direction, 270 degrees in total—3/4 of a full circle. How far can you turn your head? About 90 degrees or so. That’s because we have 7 vertebrae in our necks while owls have twice as many—14 vertebrae. Try this: keep your head still and move your finger back and forth in front of your eyes. How do you follow your finger? By moving your eyes. Now, try it again but keep your eyes still and move your head only. Very different experience, right? Now move your finger behind your head and try to see it without using your eye muscles. Can’t do it, right? Well, an owl could see it there!

Spectacled owl
More cool stuff about owls’ eyes: they are on the front of their faces, like ours are, so they have “binocular” vision which allows them to see in 3D. This helps them to hunt accurately by sight. They also have 3 eyelids: a top, a bottom and a third, transparent lid called a “nictitating membrane” which they use to protect their eyes while they are attacking prey or feeding their young. They will also close it during high-speed flight to keep their eyeballs from drying out. 

Owls can also dilate or contract each pupil independently of the other, which is a big help if a full moon is on one side of them and a dark forest on the other and they are trying to spot prey. Can humans do this? No, if you see someone with two different-sized pupils it’s a pretty good indication that they might have suffered a brain injury!

[The spectacled owl has a sharp, hooked beak and very sharp, curved claws. It feeds mostly on small mammals and birds but because it has no real sense of smell, what mammal do you think is an unusual part of its diet? The skunk! Owls will eat skunks where many other predators will not because of their smelly defense mechanism.]

The spectacled owl's markings are excellent camouflage; in fact, with its eyes closed it’s very difficult to spot in the trees. This allows it to perch on open branches along the edges of the forest and hunt in open clearings.

The spectacled owl’s main habitat, the rainforest, is one of the most threatened and rapidly disappearing ecosystems on Earth. As public awareness of this problem grows we, as humans, can work together to help ensure their survival well into the future.

Mammal, sea invertebrate, bird. What could be next? Let’s go see an animal with, unlike the owl, very poor senses of smell and sight that finds its prey in a whole different way!


And off we'll go to see the boa constrictor, unless I head straight for the nearest bar for a shot of something! Thanks for playing along with me; hope you learned something or had fun...or, better yet, both.

2 comments:

  1. I am not a big fan of birds, but owls are one of the exceptions. They are gorgeous creatures and a delight to see/read about/understand. I've never heard of the spectacled owl before so I really enjoyed this blog. All owls look intrinsically wise, but a spectacled owl looks even more sagacious!

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    1. If you get a chance, search for pictures on the internet of a juvenile or younger spectacled owl—there's one in this piece but it's a side shot. They are the reverse of their parents: white with black masks. And they are almost unbearably cute. :) Glad you liked this post! Thanks!

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