Squirrels have a secret weapon!

[beige_alert]

Here in the NewScientist:

The ground squirrel heats up its tail then waves it in the snake’s face - a form of harassment that confuses the rattler, which has an infrared sensing organ for detecting small mammals.

This defensive tactic remained invisible to biologists until they looked at the animals through an infrared video camera.

(via the ever-amazing Brad DeLong)