You don’t have to be a seasoned duck hunter to be familiar with the sight of a swimming duck suddenly disappearing from view as they dive deep underwater.
Many duck species, such as pochards and sea ducks, are proficient at foraging for food in the depths. But have you wondered how exactly ducks find food when they’re underwater?
Not only do ducks have excellent eyesight, but their eyes have adaptations that put them at the advantage in their aquatic foraging.
In this article, you’ll learn more about duck eyesight and the physical advantages ducks have to aid them when searching for food underwater. I’ll also answer some related questions you may have to help you better arm yourself with knowledge before your next duck hunt.
Can Ducks See Underwater?
Ducks have amazing eyesight, which helps them study the landscape as they migrate, find habitats adapted to their needs, and avoid predators.
And these advantages absolutely extend to the water as well. However, how well a duck needs to be able to see underwater differs from species to species!
While multiple species of duck forage for food in water, they don’t all do it the same way. Some species of duck will “dabble,” meaning they stick to shallow waters and “tip up” to look for food near the surface.
Diving ducks, on the other hand, find food much farther out, reaching depths between 10 to 16 feet. The long-tailed duck has even been known to get as far as 200 feet deep!
Keep in mind, the ambient light that will filter through the water at 10 feet is worlds different to that of 200 feet, so depending on the type and time of day that a species prefers to forage, a species’ need for low-light vision will also differ.
A study looking at the visual ability of waterfowl found that eye shape was generally different depending on how a species forages. Diving species and pursuit-diving species were found to generally have smaller corneal diameters. This was weird since larger corneas are usually better for low-light vision – the bigger the cornea, the more surface available for light to filter in.
The researchers hypothesized that the smaller corneas are partially due to diving ducks’ ability to constrict their pupils, changing the shape of their eyes. This amazing ability lets ducks compensate for the different refractive index of water, resulting in a clear view even below the surface!
Since the size of the cornea is closely linked to the size of the pupil, the thought is that the smaller cornea size allows for better constriction and therefore, better underwater vision!
How Do Ducks See Underwater?
We’ve already looked at cornea size and constriction, but that’s not the only thing that helps ducks see underwater.
In fact, there are a lot of physical adaptations that make ducks so adept at foraging, both in and out of the water.
Ducks Have Built-In Goggles
Okay, not quite, but it’s not far off either. Like all birds, ducks have a third eyelid called a nictitating membrane, which can be closed over the eye independently of the other eyelids.
Because it’s semi-transparent, the nictitating membrane can protect the eye from wind, dust, or in this case, water, all without severely impacting visibility. Hence, built-in diving goggles!
Ducks Aren’t Distracted By Pesky Blood Vessels
The pecten oculi is a unique structure present in the eyes of birds and some reptiles. In animals with this structure, blood vessels are concentrated within the pecten oculi rather than being scattered throughout the eye.
This keeps blood vessels from obscuring the retina and clouding the vision, allowing ducks (and other birds) to have much clearer sight than is possible for humans. It’s a pretty helpful adaptation underwater, where murkier depths and floating particles require much better vision!
Ducks Have Excellent Color Perception
Ducks have four types of cone cells in their eyes, unlike humans who only have three. This helps them see a much greater depth and detail of color.
Not only that, but with their extra set of cones, ducks can even perceive ultraviolet radiation! With such a keen color sense, ducks can pick out details that humans wouldn’t have a chance of noticing.
Ducks Are Cross-Eyed – In a Good Way!
Unlike predator animals, which have eyes that face directly forwards, ducks have eyes on either side of their head, giving them a 360-degree view of their surroundings. This can be both a blessing and a curse. Their field of view is much better, and they can spot food sources in all directions.
However, their depth perception is actually much worse. To help make up for the lack of depth perception, ducks can control their eyes independently of each other, otherwise known as binocular vision. (As opposed to binocular vision, where two eyes face the same direction.)
When a duck spots something in the distance (or in the deep), it constricts just a single eye, changing the curvature of both its lens and cornea to focus directly on what it sees.
Can ducks see objects in front of them?
Since ducks have eyes located on either side of their heads that they see out of independently, they can’t really focus their vision straight ahead. In fact, there are only one duck species that has that ability — the blue duck of New Zealand.
What foods do ducks hunt for in the water?
Ducks will eat a variety of foods in the water, anything from small aquatic bugs and mollusks to seeds, roots, and vegetation.
Ducks are omnivores, so they’ll eat whatever’s available when foraging, whether on land or in water. and will forage for food depending on what they find in their environment.
What are dabblers?
Dabblers are ducks that forage for food in shallow waters and mud. They don’t usually dive deeper into the water in the way that diving ducks do.
As a hunter, you probably already know that ducks have powerful eyesight, but it bears repeating.
Remember, even underwater, ducks can have a crystal clear sense of sight. That means, if you’re hunting ducks as they’re foraging, you can’t rely on the water to obscure you from sight or let you get into position unseen.
Get the right lures and the right camouflage, or you won’t have a chance of fooling a duck in the water.