How bad is it for the environment when humans kill off apex predators?

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This is making the assumption it’s bad for the environment, but, I imagine it is when sharks and other large mammals and sea creatures can grow for hundreds of years. Each ecosystem needs a very delicate balance to survive and when bald eagles are getting exterminated by chemicals that humans created, for example, it can’t be good for the environment.

In: Earth Science

When you kill off a predator, its prey makes too many babies. They make enough to replace themselves **plus** enough to feed the predator. When the predator doesn’t eat it’s share, there are too many prey animals. There isn’t enough food for that many, so they begin to starve to death. You have more starving animals, rather than the right number of healthy ones.

The big problem is that all the animals the apex predator used to eat will keep breeding and consuming resources like they did when the apex predator was there. Thus they can over shoot the [carrying capacity](https://en.wikipedia.org/wiki/Carrying_capacity) of the ecosystem. Humans can mitigate this by appropriate population control measures, including hunting.

Research what happened in Yellowstone National Park when the wolves that lived there were hunted to near extinction.

You are right, it is DEVISTATING to the environment when an apex predator is wiped.

Apex predators control all lower trophic levels (“trophic” referring to the food web). In reality trophic relationships are very complicated but you can think of it like:

Wolf eats deer, deer eats plants, plants eat sunlight.

Wolves keep the deer population in check, deer keep the plant population in check.

There’s another part of this to keep in mind: [predator/prey population oscillation](https://2.bp.blogspot.com/-Za9CD_EMUJU/WlqLj25TCQI/AAAAAAAAAXU/47lB-wt1bScr9EGavkdsrkzt1_y38pMjwCLcBGAs/s1600/PredatorPrey2.jpg). When there’s an excess of deer, the wolves get to eat more deer. Deer population falls back to a reasonable level, wolf populations rise. New lowered pop of deer can’t sustain new high wolf pop. Wolf pop goes down, less wolves means more deer. It’s a rise-and-fall balance.

We do see this oscillation with deer and plants as well, but remember that food webs are complicated, and species realistically need a few relationships to keep them completely in check. One predator on its own would wipe out all the prey without competing predators and prey, for instance. [You can play a great simulation here](https://ccl.northwestern.edu/netlogo/models/WolfSheepPredation).

No wolves? Too many deer. WAY too many deer. Deer eat all the plants. No plants, nothing for deer to eat. Deer starve. Now everyone’s dead.

That kind of thing happens when any part of the trophic system is wiped out, but it’s especially bad with apex predators because of another phenomenon: [mesopredator release.](https://www.britannica.com/science/mesopredator-release)

A mesopredator is a non-apex predator (like a raccoon or a housecat). Apex predators keep them in check, too.

Coyotes are a famous example. Coyotes avoid territories that wolves/cougars inhabit. They also eat far more little animals (rabbits, mice, songbirds, etc) than wolves do. So any area that has wolves in it, the little animals aren’t *safe* per-say but they aren’t under nearly as much pressure. Without wolf territories keeping coyotes at bay, small animals’ populations suffer huge losses.

So without an apex predator, big prey populations go wild, which makes plant populations die out, which makes big prey populations starve and die out, and mesopredator populations go wild, which makes small prey populations die out, which makes mesopredator populations starve and die out. Without apex predators, everyone else dies too.