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The dark wings of seagulls actually play a vital role in flying efficiently and agilely. Photo/journalist
So seagulls can still fly well and be as agile as birds that have long thin wings. The reason is that the dark color on the gull’s wings can reduce the density of the air above it.
In 2017, scientists found that the black upper surface of an albatross wing is about 10°C hotter than the white surface underneath. This condition reduces the density of the air above it.
The dark color on top of the gull’s short, broad wings also helps change the temperature of the air around it. This allows the gull to glide efficiently without compromising its agility.
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As a result, the viscosity of the air increases which results in less drag and extra lift for more efficient casting. “Once they’re in the air and foraging for food, that’s when this dark pigment seems to come into play,” said Madeleine Goumas of the University of Exeter as quoted by the Newscientist page on Tuesday (22/11/2022).
Birds that fly tend to have long thin wings. However, seagulls have a trick that allows them to fly with short, wide wings.
Birds tend to have relatively long, thin wings to support long-distance flight. Meanwhile, shorter and wider wings allow for more energy-efficient movements such as turning and taking off.
“Seagulls always fly and take off. If a bird has long wings for gliding, it cannot lift its body. But some gulls have evolved wings to do both,” Goumas said.
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Goumas studied the color, body and wing shape of 50 species of gulls by measuring wingspan to wingspan, known as aspect ratio. It then calculates body mass versus wing size, which is known as wing loading.
Then he evaluated how these reports related to the coloration of the posterior and upper surfaces of the wings and on the wing tips. Goumas found that higher wing loading was associated with a darker gray coat color and a proportion of black markings on the wingtips.
More specifically, species with larger bodies and smaller wings, such as the Greater Gull (Larus marinus) and Olrog’s Gull (Larus atlanticus), tend to have darker coats and wing tips. Meanwhile, the lightest color in birds with smaller bodies and wider wings, such as the ivory gull (Pagophila eburnean), which is entirely white.
“Seagulls are different from albatrosses and many other seabirds in that they spend a lot of time on land and don’t move much. Gulls fly a lot in search of food, so this calculation makes sense,” Goumas said.
(wib)
