The team examined thick-billed murres at a colony in Nunavut, Canada, and pelagic cormorants at Middleton Island, Alaska. They injected the birds with stable isotopes of oxygen and hydrogen to serve as tracers to mark the physical costs of their activities. The team also fitted them with time-budget devices that track those activities—recording movements, speeds, and other data much like pedometers do.
So by measuring lots of birds and combining their time budgets with the total costs of living from the isotope measures, it is possible to calculate how much each component of the budget costs," explained study co-author John Speakman, who leads the Energetics Research Group at the University of Aberdeen, Scotland.
Penguin bones also thickened over the ages, as lighter bones that make it easier for birds to fly gave way to more dense bones, which may have helped make them less buoyant for diving. These new findings from other diving birds like murres provide an elegant explanation of a key step in the wing-to-flipper transition. Katsufumi Sato , a behavioral ecologist at the University of Tokyo's Ocean Research Institute and a National Geographic Society Emerging Explorer, added that the work indicates an important reason why penguins stopped flying and evolved larger body sizes—they needed an edge in the water.
Bigger bodies boost dive efficiency and allow for longer dives, which may be why rapid evolution produced so many bigger-bodied penguins soon after the animals lost the ability to fly. Comparing multiple species, in the way this study does, points to a compelling pattern, said Chris Thaxter , a seabird ecologist with the British Trust for Ornithology.
Scientists don't have fossils of flighted penguin ancestors, and the earliest known penguin dates to just after the Cretaceous-Tertiary boundary 58 to 60 million years ago. In nature such adaptations happen for good reason, typically related to survival and reproduction. So a convincing case might be made for why penguins would have given up flight while taking to the seas.
That push toward being more efficient in the aquatic environment may have been enough to tip them over the edge into flightlessness. All rights reserved. Elegant Explanation "These results make a lot of sense," said University of Texas at Austin's Julia Clarke , who studies bird evolution and how the flight stroke was co-opted for underwater diving.
Penguins Grounded by Taste for Fish? The findings reveal a snapshot showing that murres are sitting on an evolutionary knife edge. Elliott and his colleagues speculate that because the wings of a murre are still built for flight, they create drag underwater. Furthermore, their small bodies, which are just light enough for them to take off, cool down more quickly than the bulkier bodies of penguins. Louis and co-author of the paper. Wilson adds that cormorants may actually be reasonably efficient flyers but seem inefficient in this study because they are using a lot of energy to cope with cold wind blasting their wet bodies.
Others agree with Elliott's team. This article is reproduced with permission from the magazine Nature. The article was first published on May 20, Already a subscriber? Wings : Penguin wings have been converted into efficient flippers that are small and stiff.
Under the water, they prove their worth. But the wing is too inflexible and its surface area is too small to carry the penguin in the air. Why does Rain Fall in Drops. Top 10 Most Expensive Materials in the World. Top 10 Birds Of Prey. Leave A Reply Cancel Reply. Save my name, email, and website in this browser for the next time I comment.
Dense, solid bones, not hollow, allow them to dive rather than just float on the water. While no other species of bird are capable of swimming quite like penguins, there are some birds that swim and still manage to fly. The thick-billed murre is a bird that is closely related to penguins, but is capable of flight as well as the ability to swim. It requires a lot of energy for the murre to fly, having to beat its wings much faster than other flying birds in order to take to the air.
According to National Geographic, the thick-billed murre uses more energy than any other bird in order to fly. Another reason penguins lost their ability to fly was to become more competitive for food under water. By being more efficient divers, penguins were able to access deeper depths than other seabirds.
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