What makes seabirds the masters of both sea and sky?
It’s rare that an animal can master two of earth’s realms, let alone two that are complete opposites. Seabirds manage to balance a life coasting both the winds and waves thanks to a host of extreme adaptations, from airbags all the way to diving goggles.
Here are just some of the most incredible adaptations that make seabirds the masters of their tough and often hostile environments…
How do you like your eggs in the morning?
Pear-shaped, if you’re a common guillemot that is. These birds are some of the most talented anglers around, diving as deep as 100m for food, but it’s the way they lay their eggs that sets them apart from other seabirds.
Common guillemots only come to land to breed, and even then they only choose the steepest of cliff faces on which to do so. These cliff faces pose little danger for adult birds, their grippy talons and ability to fly keeping them safe despite the perilous edges. Their eggs don’t have such adaptations and are at the mercy of both gravity and clumsy parents, knocking the eggs around as they shuffle along the rocky outcrops.
To get around this problem, and make sure their eggs don’t simply roll off the cliff, guillemots produce pear-shaped eggs that roll in circles if disturbed from their resting place. A pointed egg is also a lot stronger, perfect for the hustle and bustle of life spent living –quite literally – on the edge.
An airbag for every occasion
All birds possess an airbag, a space within their bodies that helps them move air in and out of the lungs. These airbags help birds to fly and, in the case of seabirds, stay buoyant as they float on the ocean’s surface.
Plunge-diving seabirds, like the gannet, have another use for their internal airbags – one that keeps them injury free as they dive into the water at speeds of over 55mph. As the birds approach the water, their thin nostrils are covered by a flap of hard tissue, stopping water from rushing into their respiratory system. The airbags then help to cushion the blow as they hit the water, strengthening their necks to help prevent breakage.
Masters of disguise
Most seabirds tend to sport a rather bland plumage of dirty whites, browns and blacks, a coloration that helps them to blend in with their surrounding environment. Like sharks, snakes and even some military planes, seabirds employ a camouflage known as ‘countershading’.
With darker colours on their backs, and lighter colours on their bellies, seabirds are hidden from potential predators both above and below. This helps them while fishing, keeping them safe from voracious marine predators, but also while nesting, darker colours helping them to blend into the cliff face and avoid any dive bomb attacks from larger, predatory seabirds.
Living between two realms creates some tough challenges, especially when it comes to sight. Eyes are often shaped to see and focus on objects within the medium that the organism lives in, so for us humans our eyes are designed to work in air, but not so well underwater.
Seabirds, however, get the best of both worlds – some species, like gannets, able to change the shape of their eye’s lenses within a tenth of a second. Such a quick change allows them to focus on objects under the water and snatch their slippery prey before it can swim away.
Seabirds also lack the ability to see UV light, a type of light that many other birds can see. All birds have tiny droplets of oil in the light-sensing cells of their eyes, enhancing their colour vision. Scientists theorise, however, that in seabirds these droplets of oil filter out dangerous UV, rather than improving the bird’s colour vision. In simpler words, seabirds may also have their own, built-in sunglasses.
4Ocean is helping to save our seabirds one pound at a time. You can support them by purchasing one of their limited edition bracelets– each one pulling a pound of trash from our coastlines – or by reading more about their ‘Save the Seabirds’ cause here.