For over two centuries, scientists have maintained that hummingbirds suck in nectar by capillary action (the same way liquid gets sucked up by a straw), using the tube-like channels that lie inside their tongues. However, a new study done by Alejendro Rico-Guevara, an ornithologist from the University of Connecticut, refutes that, and he has video footage to prove it.
The reason for the original thesis was based on two observations - the efficiency with which these little birds drink the nectar and the presence of the tubes inside their tongues. However, the one thing that always puzzled scientists was that for capillary action to work this efficiently, the sugary solution would have to be of a lower concentration so that the liquid could be drawn in. But all tests seemed to indicate that hummingbirds did not care for such low levels of sugar - Instead, they favored nectar that was thick and sticky.
Intrigued to investigate why, Alejandro Rico-Guevara and his colleague Margaret A. Rubega decided to conduct some experiments. They began by creating see-through flowers fitted with high-speed, high magnification video to record the tongue action of the bird as it drank nectar.
What they saw was quite amazing - The tubes were not straw-like devices meant to simply draw in the liquid. They actually opened down their sides when they came in contact with the nectar. Then, as the hummingbird pulled its tongue back, they magically zipped up, helping transport the nectar into the beak. This, according to the scientists explains why the birds are able to take in concentrated sugary solutions quite easily. It also shows how wrong we have been on what sugar levels they prefer - Something to keep in mind, the next time you are filling up that hummingbird feeder.
But, the scientists are not done yet - They still don't know how the nectar that is lying inside the mouths gets swallowed by these energetic birds and, they intend to find out - So stay tuned!
Hummingbirds are amongs the smallest but most active of bird species - Their wings flap up to 90 times per second and heart rates exceed 1,200 beats per minute. In order to keep this level of energy, they need a lot of fuel and can down up to 43 grams of sugar water in one day! And maybe now that we know to give them a thicker concentration, they will not have to work as hard, to get their daily food requirement.
Resources: wired.com, pnas.org