The Eyes Have It
by Kevin Mack, PAWS Wildlife Naturalist
In
previous installments of Wild Again we
took a closer look at bird beaks (Profiles
of Diversity, August 24, 2005) and feet
(Amazing Feets, January 11, 2006). In
this issue I would like to focus on the
part of the bird that...well...focuses.
Bird eyes are incredibly varied, exhibiting
not only differences in size and color,
but also in shape. Although most look
similarly rounded externally, bird eyes
often have a tubular rather than globe-like
shape. Birds are able to change both
the shape of the lens and the eye itself
when focusing, unlike our eyes in which
only the lens changes shape. Their retinas
are far more densely packed with rods
(light sensitive organs) and/or cones
(color sensitive organs) than are our
own. They also have relatively large
portions of their brain dedicated to
processing visual stimuli. In short,
they see better than we do. How much
better, we can only guess.
We
will never be able to experience the
world through the eyes of a bird, but
we are able to appreciate the external
beauty of the eyes themselves. The following
photos literally put you eye-to-eye with
a number of PAWS’ avian patients.
This beautifully shaded eye
belongs to a Laysan Albatross. The dark
colored feathers around the eye may help
to protect it from the sun’s glare.
The small feathers above the
eye of this Merlin almost look like eyelashes,
and they likely serve a similar function.
A bold orange stripe draws
attention away from the eye of this Varied
Thrush.
Although
Barred Owls typically only weigh about
1.5 pounds, their haunting dark eyes
are as large as our own.
Although this Horned Grebe
had recently been oiled, his eyes were
not irritated. They are naturally blood-red.
The Western Grebe’s eye
is generally a deep red color as well,
although some may hint at an almost orange-red
color.
Clark’s Grebes are very
similar to Westerns, although white feathers
extend above their red eye.
Killdeer have large, dark eyes
circled by red lids. The eyes are set
on the sides of the head, allowing the
bird a very large field of view.
As is the case with most predators,
the red eyes of this adult Cooper’s Hawk
are set on the front of the head. This
gives the bird binocular vision which
allows for excellent depth perception.
This eye belongs to a Sharp-shinned
Hawk, a smaller cousin of the Cooper’s
Hawk.
A prominent ridge can be seen
above the eye of this young Red-tailed
Hawk. This may help shield the bird’s
eye from the sun as he glides high in
the air.
The ridge is even more noticeable
above the eye of this immature Bald Eagle.
This yellow and red eye belongs
to a Great Blue Heron. The skin surrounding
the eye is certainly suitable considering
the bird’s name.
Notice the edges of the pupil
on this Pileated Woodpecker. The edges
are irregular rather than smooth.
It is an amazing feeling to
be looked at by an owl. Even small species
like this Northern Saw-whet Owl have
impossibly large and expressive eyes.
The bright yellow eyes of the
Snowy Owl stand out in stark contrast
to the white feathers that surround them.
The iris of this Great Horned
Owl’s eye appears to have an almost
velvety texture. The gaze of this species
has an especially hypnotic quality.
Even a bird as tiny as the Northern
Pygmy Owl can appear to be fierce with
eyes like this. Considering they sometimes
catch birds larger than themselves, I
guess there is more to their fierceness
than just a gaze.
In many bird species, the color
of the iris changes as the bird matures.
Compare the eye color of this mature
Bald Eagle to that of the immature eagle
above.
This amazing pale-blue eye belongs
to a White-winged Scoter.
At this time of year, you may
find a crow on the ground that appears
to be having difficulty flying. There
will probably be other crows in the trees
above you cawing and dive-bombing. Take
a look at the eyes
of the crow on the ground. If they are blue, like this
one, you are looking at a juvenile bird. If the bird
is uninjured and not in immediate danger (e.g. not
sitting in the road), it is best to leave it alone.
As the young bird matures, the eye color will change
from blue to brown.
The blue-green of this Double-crested
Cormorant’s eye is one of my favorite
colors. This photo does not fully do
it justice.
One
hundred and fifteen wild animals were
released between May 18th and June 16th,
2006. Thanks to all of you for
helping to make these releases possible.
Wildlife
Releases: May 18 - June 16, 2006
- Eastern Gray Squirrel- 16
- Eastern Cottontail- 6
- Virginia Opossum- 12
- American Robin- 19
- Band-tailed Pigeon- 2
- Steller's Jay- 3
- Brewer's Blackbird- 2
- Spotted Towhee- 2
- Short-tailed Weasel- 1
- Mallard- 33
- Raccoon- 6
- Glaucous-winged Gull- 1
- House Finch- 1
- American Crow- 4
- Bewick's Wren- 6
- Winter Wren- 1
210
wild animals have been released since
the beginning of 2006.
Thanks to all of you for helping to make
these releases possible!
All
rights reserved. ©2006 Progressive
Animal Welfare Society
 A
Northwest leader in protecting animals
since 1967, the Progressive Animal Welfare
Society (PAWS) shelters homeless animals,
rehabilitates injured and orphaned wildlife,
and empowers people to demonstrate compassion
and respect for animals in their daily
lives.
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