And by “roar” I include growling, hissing, screeching or otherwise making noise. I’m not talking about noises they might make when they are the ones being attacked, or when they’re fighting with other members of their own species for territory or mates, or even with members of other species for territory. I’m talking about pouncing on or otherwise attacking some other animal in order to eat it.
This seems to be extremely common in fiction–scary dangerous monsters (whether tigers or dinosaurs) always seem to stop and roar before they try to eat the heroine. It seems to me that wouldn’t really make much sense in real life–wouldn’t that just warn your would-be prey, and generally waste time and energy?–but I thought I’d see if any of our resident naturalists have the straight dope on this.
Dogs wolves will commonly yap while hunting in groups as a method of maintaining communication between pack members. These aren’t growls of course, but they are noise made while hunting.
My capuchins will squeak threat at their prey if it bites them or startles them, but it’s always in response to the actin of the prey rather than something they do first.
Predators don’t growl or roar at prey (as you suspect that would be counterproductive). But they do roar at perceived threats. For a big, wild predator, humans are unfamiliar, and thus are treated with a bit of caution. The tiger in your jungle tale will sneak around the hero, roar if she gets close, and attack if she ignores the warning and moves even closer.
Years ago, when I was camping in the Darien wilderness of eastern Panama, I had a jaguar come prowling about the tent at night. We could hear it making short, deep, grunting sounds as it circled the tent in the darkness. I have been told that this is a sound they make when they are curious about something. My Indian guide, who was in a open lean-to outside the tent, said it was hunting. (I’ll add that none of us got much sleep that night, even though jaguars are not supposed to regularly attack humans. :eek:)
Large predators are generally not going to make noises if they are stalking or chasing their prey. However, if the prey shows some resistance, I could see a predator roaring or making noise in order to intimidate the prey.
What about predators that can only chase moving animals?
Cheetahs (not roarers) can’t chase their prey unless it’s running. Something about movement triggers the kill instinct, I guess. They sneak up to the antelope herd, then bolt upright and startle the herd into making a break for it.
If there are other animals that do this, then a roar has a use.
Gah, I can’t write. Does what I just wrote make any sense?
I’m told that that’s so the cat knows which way to run. If the prey is standing at B, it can go to A or C. So if the cat pounces toward B, the prey will surely be gone by the time the cat lands. So it waits. And creeps. Then it scares the prey into “making a decision”. And the chase is on…which the cheetah wins, of course.
So if I have this right, if a tiger is going to eat me, I probably won’t know it until I feel something biting at my neck. But if it’s scared of me or wants to alert me to impending territorial disputes it’ll growl/roar at me? How about bears? Other big cats?
Well, some prey, like rabbits and young deer and such, do tend to freeze when they’re scared. But that makes sense for them, because those kinds of animals tend to be in some kind of cover, and freezing makes it much harder to spot them (and they probably won’t win a straight-out footrace if they do sprint away). But they will start running once it’s clear that they’ve been spotted.
But big animals in the open that freeze when a lion roars at them will probably not be around to pass that trait on to the next generation.
In general, a hunting strategy that relies on your prey making dumb mistakes doesn’t work for very many generations.
I’ve always wondered that. Whenever I watch Jurassic Park, I wonder how a real T-Rex would act. They always make a huge amount of noise and gnash their terrible teeth and so on. And as mentioned, it does seem a bit counter productive (as does spending all that effort hunting puny humans).