This male Sparkling Violetear hummingbird (Colibri coruscans) extends his tongue after feeding on nectar, readjusting the forked tips. (Photo : Kristiina Hurme/UConn)
Scientists have always thought that hummingbirds used to feed on nectar with their tongues via capillary action where liquid flows through a narrow tube without the use of gravity much like a straw.
However, a team of scientists from the University of Connecticut has now debunks this capillary action or "wicking" theory after observing 18 different species of hummingbirds that are feeding in the wild with the help of high speed cameras as scientists revealed that hummingbirds drink nectar not like a straw but with tiny, pumping action with their tongues.
Their tongue is flat inside their beak but as they are about to reach the nectar, the tip of the tongue erects and becomes inflated as it fills with nectar as seen during a slow motion replay of the video.
When the hummingbird squeezes out the liquid from its tongue, it collapses again to its normal state where it accumulates elastic energy that is responsible for the pumping action to suck in more nectar which all happens in one tenth of a second.
Since the researchers have already captured this process on video, the team is now seeking for a logical, mathematical explanation for this. Researchers were first skeptical about the capillary action theory that enabled the hummingbirds to extract nectar however it was only accomplished in limited rates that led them to re-examine how hummingbirds use their tongues.
According to lead author of the study, Alejandro Rico-Guevara, the actual drinking process can be observed via high speed video however they are still in the process of developing fluid dynamics to test the theory of this pumping action as opposed to capillary action.
Scientists have collaborated with experts in the field of fluid mechanics where they have tested on numerous hypotheses where the team was able to reveal the physics behind this micro pumping action while feeding.
This new study shows how hummingbirds drink and feed on nectar with the first real mathematical model that can accurately depict their energy intake using these micro pumping actions that add to the better understanding of how hummingbirds forage for food and their overall ecology, adds Rico-Guevara.
This new study is published in the journal, Proceedings of the Royal Society B: Biological Sciences.
