Mechanics of Snow-diving Animals

Some fox species plunge-dive to catch prey (e.g. rodents) underneath a pile of snow. This hunting behavior is known as “mousing.” In this behavior, the diving speed can range between 2 and 4 m/s. Here, we investigate how foxes dive into snow without alerting prey. An important factor to consider in this mousing process is the impact on snow. Snow is a compressible fluid consisting of 1~10% ice and the rest of air. When a tapered object (in this case, a fox’s head) compresses or dives into the snow, the pressure/information front does not propagate fast enough for the prey to detect and escape. Animals that portray this mousing behavior, such has red foxes, arctic foxes, and even servals and other feline species, all generally share a slim, narrow facial structure. In this study, 3D printed fox heads and similar funnel-shaped objects are dropped into a pile of snow to understand the propagation of the pressure in snow and the drag on the object.