You've seen videos of foxes hunting for mice underneath a blanket of snow. They don't catch the mouse (or mole or other creature) all the time, but enough to make it worth the effort. How does a fox sense where its prey is, how fast it's moving, and where to jump to intercept it? Robert Krulwich at NPR looks at some of the research on foxes and their winter prey. A Czech study had 23 hunters and biologists record 84 foxes making over 600 snow jumps.
When they looked at each other's notes, the researchers saw a pattern: For some reason, Czech foxes prefer to jump in a particular direction — toward the northeast. (To be more precise, it's about 20 degrees off "magnetic north" — the "N" on your compass.) As the video above says, most of the time, most foxes miss their targets and emerge covered in snow and (one presumes) a little embarrassed. But when they pointed in that particular northeasterly direction, Ed writes, "they killed on 73 percent of their attacks." If they reversed direction, and jumped exactly the opposite way, they killed 60 percent of the time. But in all other directions — east, south, west, whatever — they sucked. Only 18 percent of those jumps were successful.
Strange, but how does having an internal compass help a fox hunt prey? We don't know for sure, but a possible explanation is offered at NPR, along with a video and more illustrations.
(Image credit: Robert Krulwich)