![]() ![]() “Our job is to describe the mechanism and then surely engineers will come and think what this can be used for. “This is an unexpected new way to move fluids at very small scales,” said Rico-Guevara. And understanding hummingbirds’ strange, clever tongues may also help engineers develop elastic-walled flexible tubes that, like the birds’ tongues, serve as tiny pumps. ![]() In order to develop models about how hummingbirds forage, after all, it’s important to understand how they actually eat. This research, according to Rico-Guevara, helps biologists understand how hummingbirds evolved and how they might be affected by environmental change. Rico-Guevara is now studying how other nectar-eating birds’ tongues work similarly or differently to hummingbirds’. “There are other birds that have also evolved to feed on nectar, and they have similar-shaped tongues,” said Rico-Guevara.įor instance, honeyeaters have tongues that look bristled at the end, and flowerpiercers have tongues that look like upside-down versions of hummingbirds’ tongues. Similar SpeciesĪnd it may be that hummingbirds aren’t the only ones who’ve evolved this feeding mechanism. The researchers published their results in the Proceedings of the Royal Society B. Every time the bird presses its tongue to release a new mouthful of nectar, it’s also re-setting the pump for another mouthful. Compressing the tubes stores potential energy in their walls, so when the tubes start to expand again, that energy is released, and it draws nectar inside. When the bird sticks its tongue out again, the tubes are able to expand. When the hummingbird draws its tongue back into its bill at the end of each lick, its bill squeezes the tongue from above and below, squeezing out the nectar from the two tubes at the end. It works like this: While feeding, the hummingbird’s tongue is flicking in and out of its bill fifteen or twenty times every second. “What we found is that there is actually a micropump which is transforming the whole tongue shape, and that transformation of the tongue shape is what actually pulls the fluid inside,” said Rico-Guevara. ![]() “It's not only a challenge to set everything up, it's also a challenge to convince a wild hummingbird to feed right there,” said Rico-Guevara.īut 18 species of hummingbirds did, eventually, feed at the transparent flowers, and the cameras saw a mechanism very different than capillarity at work. They built transparent artificial flowers so the cameras could see what was happening inside the flower, set up lights and cameras, and waited. Rico-Guevara and his colleagues teamed up with a mechanical engineer to study hummingbird feeding using high-speed video cameras. “I felt that there was something off,” said biologist Alejandro Rico-Guevara, adding, “People weren't looking at that basic assumption, because it was established so long ago that it was hard to believe that it was wrong.” Hummingbird in High Speed The trouble was that the amount of nectar consumption predicted by the capillarity model didn’t always match what biologists saw hummingbirds doing in the wild. That is the same mechanism that lets paper towels and sponges absorb water into their pores.īiologists liked capillarity as model for hummingbirds’ drinking, because the equations that described it were easy to work into larger-scale models that predicted how hummingbirds forage. Because of this pair of tiny tubes, many biologists assumed that nectar just flowed up the tubes thanks to a passive process called capillarity. Hummingbird tongues are even stranger they’re forked at the end, and each fork is shaped like a groove whose edges curl inward, forming a tube on each side. ![]() Bird tongues are very different from mammal tongues they’re less fleshy, and they don’t have muscles in the front. ![]()
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