Owls are amazing birds that are found in all regions of
Earth except Antarctica. They have many adaptions that allow them to be excellent
hunters, many of which to make them great nocturnal (meaning they are active at
night) hunters. Owls have exceptional hearing and sight. An owl’s ears are
actually openings, called apertures, which are located on the sides of their
heads hidden underneath their feathers.
For example, this is a Barn Owl's ear.
To assist in the triangulation of
sounds the apertures are offset, on one side the opening is higher on the head
than on the other side, giving the owl a greater ability to locate hidden prey
in complete darkness or under cover.
Owls eyes are also specialized and allow for not only good night vision
but also allow for exceptional prey tracking. Owls’ eyes are incredibly large, with some
species having eyes that are five percent of their overall mass.
This is a Great Horned Owl skull to show just
how big the eyes are in the head.
Owls have eyes
that give them a binocular view of an object, meaning they see it with both
eyes, and are always facing straight in front of the face. The owl’s eyes are
not round eye balls but elongated eye “tubes” that are not able to move in the
owl’s head so instead of moving the eye like we would the owl moves its whole
head. In the owl’s neck there are
fourteen vertebrae, compared to the human’s seven, which let the owl turn its
head a 270°.
The owl can look behind it without even having to move their
body.
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| On their feet owls have large talons to grab on to prey, four on each foot. |
The length,
thickness, and color varies by species but all owls have a locking mechanism in
their feet that allows them to grasp an object or prey with full force without
needing constant muscle exertion. Owls also have incredibly powerful beaks that
can quickly crush smaller prey.
Like other birds, owls cannot chew so their prey must be
swallowed whole or ripped into small pieces. The issue with this is that the
owl also ingests the parts that cannot be digested, such as fur and bones,
along with the parts that can be digested. To solve this problem, the owl
regurgitates (throws up) the problem parts in small compacted pellets, called
owl pellets.
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| These pellets can be dissected to see what the owl has eaten. |
These pellets are one way to determine the presences of owl’s
nests or often used roosts as they will collect on the ground around the
immediate area.
Other good ways to tell if there are owls in the area is
to listen for their calls. These include the often thought of “hoots” but also
include sounds not obviously from owls. Owls will also make non-vocal sounds such
as the bill clacking and wing clapping. A common characteristic among many owl
species is that the males are lower pitched than the females and the two are
easy to differentiate when a pair is calling back and forth. Occasionally owls
will respond to recordings but this method should only be tried sparingly as
repeated use may disturb the birds and cause disruptions during nesting season. A good website to hear the noises that owls will make is here, which has the typical owls.
But one part of owls that doesn’t make sound is their
flying.
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| This rodent doesn't hear anything coming. |
Owls have
specialized feathers that alters the way that wind moves over the wing,
reducing the sound generated. The first part is the small structures on the
leading edge of the owl’s wings that breaks up the wind. The next part is the
trailing edge comprised of flexible fringe that further breaks up the wind. And
the owl’s velvety down on the wings and legs absorb high frequency sounds that
prey, and humans, are sensitive to. All this leads to an incredibly quiet flight,
meaning owls are very difficult to detect in flight.
Not only is hearing the owl difficult but seeing it can
also pose a daunting task. Owls are often camouflaged into their surroundings
very well and when perched on trees can blend in extremely well.
The Eastern
Screech owl’s back has colorization and patterns to help it blend in to the
bark of trees while the Snowy owl, rarely seen in Ohio, is almost completely
white with few black marks so it can blend in well with the snow covered areas that it lives in. Often the easiest part of the owl to see would be
their vividly colored eyes.
-Connie
-Connie
Resources:
wildlife.ohiodnr.gov
asknature.org/strategy/938e8c4d8e2bf786fa5c9922d181273e
Picture resources;
Great
Horned Owl skull: https://www.flickr.com/photos/malama/976869585/in/photostream/
Owl
pellet dissected: https://tamaracolson.wordpress.com/students/
Eastern
Screech Owl w/ mouse: http://fineartamerica.com/featured/eastern-screech-owl-catching-prey-kevin-shank.html
Swooping Great Horned Owl: http://eyes4earth.org/2011/10/eagle-owl-in-action/
Camouflaged
Eastern Screech Owl: http://www.dailymail.co.uk/news/article-2313586/Can-make-hoot-Natural-camouflage-leaves-American-owl-barely-visible-entrance-nest.html
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