Imagine that your eyes were so powerful that all the way from the worst seat in the stadium, you could see the individual beads of sweat on the brow of an athlete as he readies himself to make the decisive play. Or if sports aren't your thing, you could read a book across the length of the Library of Congress. These eyes seem fictional, and ridiculous. However, these eyes are very real and integral to the survival of many species of predatory birds.
Golden Eagle, and its brilliant eyes
Most hawks, falcons, kestrels, kites, eagles, among others, all have this incredible telescopic vision. Their eyes are designed quite differently from our own to allow for this specialized sight. First the importance of the eye in raptors is noticeable simply by the size. The human eye makes up less than one percent of the head's weight, whereas in many birds this can be beyond ten percent.
Red-tailed hawk (dark morph)
Now as you probably know, human eyesight is quite good in the animal kingdom, for example your dog is fairly blind, and struggles to see color, or fine details. Our eyes are actually some of the best, however, still pale in comparison to most raptors. The eyes themselves function differently due to their unique construction. Similar to a telescope the eyes are built so that there is a long distance in between the lens and retina.
Just like zooming on a camera, which extends the lenses apart, this extra distance is amplified to the receiver and a highly zoomed image becomes available to the raptor. Not only is the distance great between the lens and retina, but the retina itself is made up of cones. Cones are the actual structures that receive the light from the outside world and translate it by wavelength to explain color and shape to the brain.
Merlin eyes the camera man
Cones are specialized for daytime and visualizing detail in well lit environments, and critical to providing the detail for the highly zoomed images. Interestingly owls, who are also raptors, have the opposite strategy. Their retinas are made up of mostly rods, which disregard the specificity of color and focus more on picking up the tiny traces of light to see in the darkness. Their eyesight is still fantastic but highly adapted to fit their nocturnal lifestyle.
Eurasian Eagle Owl
Really quite interesting how the two evolutionary strategies of nocturnal(active at night) and diurnal (active in the daytime) birds of prey appear through the construction of the eyes themselves. While both owls and diurnal raptors have incredible vision it is specialized for the different ecological niches they occupy. On the flip side, the prey of these creatures can have almost no vision at all.
Juvenile Red-tail Hawk with rabbit for lunch
Moles for example live underground almost all the time, but when they surface, with their squiggly mouthparts fluttering in the wind, they make a tasty snack for a hawk. Their eyesight is primitive compared to the hawks, however it is similar in its detailed specificity. Like the hawks eyes are perfect for flying two hundred feet in the air and seeing the moles tiny head pop out of the ground, the moles eyes are incredibly light sensitive. Critical so they can be aware of any cracks or holes in the earth above them that let in light and maybe let in a predator.
Next time you see a hawk spin its head to look at you, be sure that its seeing every individual freckle. These raptors soar above and look like tiny dots to us, yet they are scanning each pebble on the ground for any movement, and then dive bombing with uncalled for speeds to bring demise to an unlucky rodent.
Golden Eagle smirks
Let us know in the comments what your favorite bird of prey is, and what kind you have around your house! If you think that living in the city means there are no raptors, you are sorely mistaken. If you want to know more about raptors in the city you can check out this article from a few months ago! https://www.havasiwf.org/post/sharing-the-road
Stunning photos by Alex Havasi
Isaac Yelchin is foremost a herpetologist. He studies lizards, frogs, newts, and the like. Specifically, he spends all day and night thinking about what it is like to be an animal. What are the animals thinking about? What is their perspective? When he should be working, he sits and stares at his pet lizard asking himself these questions