Quote Originally Posted by chris-uk View Post
I thought their hearing was quite primitive with their other senses developed to compensate. Although this isn't based on any sort of active reading I've done around the subject.
Is it possible that they heard a loud noise and were bringing their other senses to bear to try to identify the source? Rather than knowing it was dogs and looking to see them coming?

When I first read your reply I was going to respond with something like this "I never meant to imply they knew it was a dog but only reacted to the sound"
Now, I'm not sure that is true. Since these snakes have probably grown up in this area they may very well have known it is a dog having firsthand knowledge(being harassed or even attacked) of these predators.
I know that nothing I have posted here is even vaguely related to fact but it does bring up some interesting thoughts.
I for one think that garters have good memories and feel they could learn that a certain sound means possible danger.
They certainly weren't reacting to the bird calls, motorcycles and jets sounds that are regular in the area.