I'm watching Shark Week—of course—and my ear just snagged on a term I've heard a lot in the past few decades. Great White sharks are, I'm told, "opportunistic feeders", and therefore they'll adjust their tactics in order to take advantage of different kinds of prey available.
Now for the first time I pause to wonder: If "opportunistic" means that it'll eat anything that comes along (anything within its range, of course; a shark won't eat plants and a bear won't eat rocks), then by that definition what isn't an opportunistic feeder? Does the word mean anything useful? This is a complaint only if the answer is No; if I'm misunderstanding something then it's a real question.
I do not eat liver. And, since 1973-4, I do not eat much chicken. I do not eat pretzels. I also do not risk the stomache chocolate might cause.
Some snakes will go for months (I am sure they are passing up opportunities) after a large meal.
Emmett
You have the advantage of me: You understood my question, but I don't yet understand the answer. Do you mean that "opportunistic feeder" does, or does not, mean something other than "feeder"?
My guess of what it means:
Lions theoretically could eat grass and plants to supplement their protein needs, but they don't. Bears, on the other hand look out for opportunities to survive on berries, roots, honey, etc, besides fish and meat.
White sharks, though strictly carnivorous, develop specialized tactics to catch different sea and land animals. Their opposite number would be whales that only open up and take in whatever plankton and small fishes that come along.
So opportunistic means looking out for a wide range of food sources.
One misunderstanding could be this: hyenas singling out the weak or sick individuals in a herd, which can be called opportunistic too, but not in the sense of 'opportunistic feeder.'
That's my best guess, claiming no authority at all.
"The fox knows many things, but the hedgehog knows one big thing."
An opportunistic feeder is an animal that is a generalist, when it comes to eating. Many animals specialize, creating a smaller niche for themselves, but one with less competition.
Bears and raccoons are good examples of opportunistic feeders--they will eat many varieties of foods, and they have many skills for discovering or acquiring those foods. They eat whatever they find, wherever they may find it. They are not picky. Plants, animals, whatever--if they can digest it, they will most certainly try to. Super bright creatures--they can open anything anywhere if there's food involved.
Pandas--which are closely related to both bears and raccoons--are NOT opportunistic feeders. They eat bamboo. They eat lots of bamboo. They are very good at stripping the tasty shoots right out of the bamboo. They are the undisputed kings of bamboo-eating.
They suck at every other kind of foraging.