PT146 · S3 · Q16 Babblers, a bird species, live

If the babblers have the means to escape predators by just flying away, then why are they doing any of this barking in the first place? Usually, if a species already has one adaptive response to a predator (fly away), it doesn't involve a second one for the same purpose (bark & hide?) Someone might like this answer thinking, "Look, they bark to warn each other to take cover, but they're not worried about giving away their position or barking long after they've taken cover, because they could always fly away." Fair enough, but that would basically explain why they can get away with continuing to bark. It doesn't provide any reason for why they are continuing to bark in the first place.

Whether they only have one predator or have many types, we still don't have any explanation for why they bark (which gives away their position) nor why they continue barking even once they've all taken cover.

A lot of us are tempted by this, thinking, "If the predators have relatively weak hearing, then maybe they can't even hear the babblers' barking, and thus it's not so surprising that the babblers are unafraid to continue barking." Two problems with that: 1. "relatively weak" is not strong enough for us to start thinking, "They're deaf". Humans have a relatively weak sense of smell compared to most animals, but that doesn't mean we can't smell a skunk's spray when it tries to ward us off. It's too much of a leap to go from "relatively weak hearing" to "the predators can't hear the barking", especially when the barking is described as loud and shrill, both of which would be the one thing someone hard of hearing could still notice. 2. If we were to think, "maybe the predators don't even hear the barking", we would be cheating the background information of the paradox. It tells us that, "these predators generally become aware of the presence of babblers only because of their shrill barks", so we KNOW that the predators definitely hear the barks.

We might keep this around on a first pass, thinking, "oh here is some utility to the excessive barking -- it alerts other animals down the way that there's a predator around." But it's not really common for animals to develop evolutionary behaviors in order to help out other species, so it's a little far-fetched to think they evolved this barking routine in order to help some other species. That's not how evolution works (unless it's a symbiotic relationship like when birds ride atop ox, and the birds eat bugs out of the ox's fur while the ox dissuades the birds' predators from coming near). More importantly, the correct answer doesn't involve this sort of stretch. It explains the babblers' barking in away that benefits the babblers. We have to prefer that story over one in which the barking benefits other species.