Also, where predator evasion is concerned, in the case of the frogs, I believe it's primarily about finding a place where you can become motionless in an environment that matches your colors.

I find it interesting that while many snakes employ the "sit still" method of camouflage, others with the appropriate pattern are able to mask their features while on the move; garters are no exception. If you were the egret, you might be snapping at twigs while trying to zero in on that one slithering twig!