A study suggests that neck length, neck muscles, and diving speed together help diving birds survive water impacts. Several seabirds, such as gannets and boobies, dive into water at a speed of around 24 meters per second while hunting. The birds’ slender and seemingly fragile necks do not crumble under the compression experienced during high-speed water impacts. Brian Chang and colleagues used experimental dives by a dead, frozen Northern Gannet as well as diving bird models to test the limits of the neck stability of plunge-diving birds. The authors found that hydrodynamic drag forces on the head might cause the birds’ necks to buckle, but analysis of musculature showed that strong neck muscles allow the birds to survive compression forces two orders of magnitude greater than that experienced during normal dives. By manipulating the dimensions and dive form of the models, the authors demonstrated that increasing the dive velocity and neck length increases the likelihood of buckling. Further, the compression force on the neck increased with skull radius, impact velocity, and beak angle. According to the authors, the birds would have to dive at a speed of around 80 meters per second for their necks to buckle, although humans would likely sustain neck injury at a speed of 24 meters per second.
Article #16-08628: “How seabirds plunge-dive without injuries,” by Brian Chang et al.