The long, thin bills of hummingbirds are one of their most distinct features. Their bills aren’t just for looking pretty—they are tools that developed to have multiple uses over thousands of years. A team of researchers has uncovered just how flexible the hummingbird bill is.
The slender nature of a hummingbird’s beak gives off the impression of a drinking straw. So, you might think it acts like a straw as well. However, that is not the case.
The researchers found that when hummingbirds feed on nectar, they quickly open and shut different parts of their bill at the same time, using their tongues to lap up nectar at rapid rates.
The complex behavior requires careful coordination and precision. The movements can barely be seen by the human eye.
“Most hummingbirds drink while they’re hovering mid-flight,” said Alejandro Rico-Guevara, the lead author of the study and an assistant professor of biology at the University of Washington.
“Energetically, that is very expensive. Flying straight at commuting speeds uses up less energy than hovering to drink.”
“So, hummingbirds are trying to minimize energy and drink as fast as they can—all from these hard-to-reach spaces—which requires special adaptations for speed and efficiency.”
Researchers have known that hummingbirds use their tongues to drink nectar at lightning speeds, but it was unclear what role the bill played until now.
The team analyzed video footage of individual hummingbirds from six different species drinking from feeders at sites in Colombia, Ecuador, and the United States.
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They then combined the footage with data from micro-CT scans of hummingbird specimens at the Yale Peabody Museum.
They came to the conclusion that the bill was important for drinking nectar and was much more flexible than they realized.
Hummingbirds have to open the tip of their bill to extend their tongue. The bill tip closes once the tongue brings in nectar.
The bill’s midsection is kept tightly shut while the base is opened slightly in order to draw nectar up the bill. Then, the bill tip is opened again to extend the tongue for more nectar. Many hummingbird species can complete this process 10 to 15 times per second.
“We already knew that hummingbird bills have some flexibility, for example, bending their lower bill while catching insects,” said Rico-Guevara.
“But now we know that the bill plays this very active and essential role in drawing up nectar that the tongue collects.”
Hummingbird bills evolved in accordance with the different lengths and shapes that flowers developed over time.
There is still much to learn about hummingbird evolution. In the future, research could focus on identifying the muscles that control these tiny birds’ rapid-fire movements and looking into other uses for the bill.
The study was published in the Journal of the Royal Society Interface.