Hummingbird uses its tongue to pump nectar
A hummingbird buzzing and hovering over a flower is a sight to behold at every encounter. Have you ever wondered how the bird licks nectar? I admit, I held a naive belief that its long and slender beak works like a straw. A new study finds that hummingbirds use their tongues to pump nectar into their mouths.
A research team from University of Connecticut, using high-speed cameras over the course of five years, captured moments of wild, non-captive hummingbirds feeding. Doing so allowed the team to describe “a hitherto undocumented mechanism of fluid transport [that] pumps nectar onto the hummingbird tongue.”
A hummingbird tongue has a cylinder-like groove running along from the tip to the mid-section. This groove can be filled with nectar when the bird feeds.
The researchers noticed that the tongue is first flattened out as it flicks out from the beak, then expands when it comes in contact with nectar. This expansion works as a pump that draws nectar into the tongue’s groove, the study concludes. Watch the video below provided by the study:
“We show that the tongue works as an elastic micropump,” the researchers report.
Prior to this finding, a widely accepted view was that nectar flows into a hummingbird’s tongue using capillary action, a passive process in which a liquid flows through narrow spaces. (An example of capillarity: if you dip a tip of a brush in water, the liquid will be drawn up against gravity between the hairs.)
The researchers say their conclusion is in agreement with their observations. The pump mechanism, as revealed by the study, is much faster than capillary action. According to their calculations, a hummingbird can only have 5 licks per second if it relied on capillary motion, whereas a pump would allow it 14 licks per second, which is very close to the actual observation.
The study is published in this month’s issue of Proceedings of the Royal Society B.
The finding that a tongue works as a pump is fascinating. But in watching the video that accompanies the study, I was astonished by the length of a hummingbird tongue. Relative to its body, the tongue is so long, that it is almost like that of a snake! In comparison, my budgie, representing parrots, has short and stubby tongue that works like a thumb to nimbly grab seeds out of cracked shells.
It’s amazing how varying shapes and sizes of tongues have come to exist, allowing birds to adapt to different lifestyles.
Update (September 9, 2015):
Now there is a great video from The New York Times, visually explaining how the hummingbird’s tongue works: