Scientists at the University of Connecticut have proved that the hummingbird does not drink using capillary action like it was previously believed, but its tongue functions like an elastic tiny pump. The paper was published in the journal Proceedings of the Royal Society B: Biological Sciences.
Capillary action or wicking is a passive process which involves rising a fluid into a narrow tube through the means of forces which attract the liquid to the internal surface of the tube. Ornithologists have assumed that this was the way in which the hummingbird drank water ever since 1830.
The new study led by Dr. Alejandro Rico-Guevara from the University of Connecticut proves that scientists have been wrong 200 years. The researchers took videos of 18 species of hummingbirds that were drinking from artificial flowers. This enabled them to remark that the hummingbird tongue has grooves like tubes which are in a collapsed state. When they enter in contact with the flowers the grooves open and they are filled with nectar. The grooves are collapsing when the hummingbird squeezes the liquid off its tongue. This loads the groove walls with elastic energy which enables the birds to pump more nectar.
Dr. Rico-Guevara explained:
A hummingbird’s tongue, which can be stuck out about the same length as its beak, is tipped with two long skinny tubes, or grooves. Rather than wicking, the nectar is drawn into the tongue by the elastic expansion of the grooves after they are squeezed flat by the beak.”
In previous studies hummingbirds sipped nectar from feeders which contained more liquid than a real flower. But in this study the researchers used wild hummingbirds, not hummingbirds kept in a laboratory. In addition they used transparent feeders which had the same shape and the same amount of nectar and calorie concentration as real the real flowers which hummingbirds like.
According to Rico-Guevara the study not only explained how the hummingbird feeds but it also offered the first mathematical tools which can be used to model the energy intake of the hummingbird. This will further help scientists understand the hummingbird’s ecology and foraging behavior. Moreover researchers are optimistic that this discovery could inspire applications in the domain of biological and artificial systems.
Image Source: jlockyer.com