What's got energy expenditure to do with logic? Isn't what you talk about Bayesian Inference?
while one scrambles up a nearby tree
I'm not sure that is just a nervous reflex or the result of the logic implication "If that's a Tiger and I stay then I will die". Even if the thought becomes hardwired, it would have to have been logically evaluated before it became subconscious. To react and be afraid, the danger must be recognized and categorized, "If the grass twitches then something moved it", etc. etc. Going down that argument, small life forms would be able of some small amount of logic reasoning, too. As long as those grow bulks of neurons, I don't see why that should be wrong.
just look at your first sentence
What are you trying to say?