Mice, elephants, and other animals hear and make sounds that are well outside the range of human hearing. It was discovered only very recently, for example, that mice sing in frequencies much higher than we can perceive. It’s been known for longer that animals, like birds, are decorated in, and can see, colors outside the human spectrum. This week scientists announce that when squirrels are faced by rattlesnakes which can see infrared, the squirrels heat their tails, making them seem larger in the infrared than they actually are. PNAS. I haven’t come across any other examples of mammals selectively heating a part of their body in order to repel a predator.
