Robotic Squirrels Battle It Out With Rattlesnakes

Interestingly, it turns out that the squirrels (North American ground squirrels, in this case) are even cleverer than that, as the same team at UC Davis have previously shown. When confronted with a snake with infrared sensing organs (i.e. a pit viper, of which rattlesnakes are one variety), they engorge their tails with blood to send that infrared decoy signal. However, when they meet up with other kinds of non-infrared sensitive snakes (e.g. gopher snakes), they only flag with their tails; they don't use the infrared trick as well:

Squirrels wield a hot secret weapon [newscientist.com]

Why the difference? Presumably because it costs energy to send blood to your tail, where it then cools as it sends out its infrared signal. Thus, in evolutionary terms, it only makes sense to incur that cost if it has an advantage. Since gopher snakes can't sense in the infrared, why bother?

Of course, with respect to the current findings, it suggests that both flagging and infrared decoy measures are important to a ground squirrel, not just the infrared part. Otherwise, why would they bother flagging? Perhaps just because they have fun annoying snakes...

And while the snakes might come off as just dumb reptiles in this story, let's not forget that those infrared sensing organs are pretty amazing as well. They have limited spatial resolution, but extraordinary temperature resolution, down to 0.001K. Indeed, once upon a time as a PhD student, I calculated that if you strapped a rattlesnake to the back of a 4 metre infrared telescope (!), it could detect the signal from Eta Carinae, one of the brightest infrared stars in the sky. Strap on thousands of rattlesnakes and count when each one rattled its tail, and you could take images:-)

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