Why birds do not fall while sleeping
It may sound like a tall tale, but that is more or less the one recounted in a recent publication by a team of scientists at the National Museum of Natural History (MNHN) and the CNRS, which explains in the pages of the Journal of the Royal Society Interface1 how birds can sleep while standing, without losing their balance. We know horses and bovines are capable of this feat thanks to their four legs, but at first glance this does not seem so evident for birds. Scientists agree that this stability comes from one thing: tensegrity. Created from the contraction of the words “tension” and “integrity,” tensegrity is the property of a structure to remain stable and balanced thanks to the subtle interplay of tension and compression in the elements of which it is made.
“The starting point for this research was trying to understand evolutionary mechanisms via functional morphology, which studies the relation between an organism’s form and functioning,” points out Anick Abourachid, a specialist on evolutionary biology, and the Deputy Director of the Adaptive Mechanisms and Evolution research unit2 at the National Museum of Natural History. “We are especially interested in bird feet.” Studying the evolutionary mechanisms in bird feet is of interest because birds are a particularly homogenous group with respect to their structure: “They are all bipedal flying dinosaurs that, since the group’s origin, have shared a structure built to be aerodynamic. They all possess, with no exceptions, a rigid torso,
