Eyelashes are something that many of us take for granted, but not all members of the animal kingdom are lucky enough to possess these handy filters. While our lashes are made from hair, those found on some bird species are composed of modified feathers. Of the species that possess eyelashes, the texture ranges from short and fine to wispy and long.

Discover why birds have eyelashes, plus the benefits they bring. And learn the reasons why a significant number of bird species don’t have any eyelashes at all.

Why Do Birds Have Eyelashes?

Some birds have what appear to be eyelashes though they are quite different from the human version. While our own eyelashes are composed of modified hair, the eyelashes on a bird are made up of modified feathers.

These might not be considered “true eyelashes” compared to the human alternative, but they are pretty close for a species that possesses no hair at all. There are a few notable exceptions to the feathered eyelash, including the ostrich, secretary bird, and hornbill.

The ostrich is a non-flying bird native to the desert of central and southern Africa. Famous for their sizeable feathered body and long skinny necks, an ostrich’s eyes can measure two inches across and possess long, luscious eyelashes. The Southern Ground Hornbill is also a non-flying native of the African Savanna, which has short legs, a vibrantly colored throat, and long eyelashes.

The secretary bird does fly; it is impressively agile in the air – but it is best known for ground-dwelling, where it forages for prey. Could it be that eyelashes are most prominent in ground-dwelling bird species because they are the ones whose eyes are most likely to attract dust and dirt?

There is a limited amount of study into the function of eyelashes on birds; still, a team at the Cornell Museum of Vertebrates has analyzed the eyelashes on 205 of the bird families within the museum’s collection, finding that around 3.5% of birds in their collection do have eyelashes. The lashes are most common among large, non-aquatic, and nonmigratory species.

Some suggestions as to why birds have eyelashes include the possibility of being used as a protective function to keep the eyes clear of dirt, dust, and sand particles when the animals are burrowing, flying, or running.

Why Would A Bird Not Have Eyelashes?

While some ground-dwelling birds possess eyelashes, there are a large number of air and water-based birds that do not. This is because birds have a kind of inbuilt pair of “safety goggles,” which they can deploy in the air or water to protect their eyes against dirt, debris, and other harmful material.

These “goggles” are essentially a third eyelid known as the nictitating membrane. This thin structure beneath the eyelid allows a bird to filter things from the surrounding environment.

Nictitating basically means “blinking,” and that’s precisely what these avians do to keep their eyes clear. The nictitating membrane is attached to the inner corner of a bird’s eye and sweeps across it horizontally. Thanks to its mostly transparent properties, the bird can continue to fly or swim while keeping its eye safe from hazards such as wind, water, or dust.

Water-diving birds such as the penguin can even adapt the shape of the eye lens to create a clear and sharp image in the water. These unique eye mechanisms mean that there is little need for eyelashes in birds like the penguin.

What Are The Benefits Of Having Eyelashes For A Bird?

Some birds have evolved their own eye mechanisms and safety features to keep their sensory organs clean, clear, and healthy. Still, there are some birds who do benefit from possessing lashes, and there are several reasons why.

Eyelashes sense dirt, debris, and potentially harmful substances before they enter your eye. In this way, the eyelashes can tell your eyes when they need to close in order to avoid hazards. They can also filter and direct air to help protect your sensory organs against the wind, rain, and other weather.

Additionally, eyelashes – particularly long or thick ones – can act as a shield against the sun. You don’t often see birds walking around in sunglasses, so in places where the sun is extreme (such as central Africa, where a number of our eyelashed birds are found), these handy features help stop the sunlight from blinding them or obscuring their vision.

Summary

Not all birds have eyelashes. Many don’t because they have evolved their own eye mechanisms to deal with the environment around them and protect their eyes from hazards. These birds possess a nictitating membrane that acts as both a cleaner and filter for the eye.

However, the nictitating membrane alone might not be enough for some bird species. Many bird species that possess eyelashes live in hot, dry places and forage on the ground for food. Their eyelashes can not only prevent debris from entering the eye, but they can also act as a shield against the harsh sun.

References

Do Birds Have Eyelashes? | All About Birds All About Birds

Birds With Eyelashes (mom.com)

Secretary Birds: Weird, but Actually Not That Weird – Scientific American Blog Network

Birds Have Built-In Goggles | Audubon