Dear Dr. Universe
What if there were no predators to eat the birds?
— Katy, Hawaii
Don’t let the lab coat fool you. I enjoy chattering at birds as much as the next cat. Staring out the window and vibrating my mouth to “chirp” helps me relax after a long day.
My wild cousins do take things a bit further — namely, predation. It’s not pretty, but it’s an important part of keeping life in balance.
I talked about predators with my friend Travis King. He’s a doctoral student at Washington State University. He studies big cats like lynx and jaguars.
“It’s a balancing act between predators, disease, food and space,” King said. “If you take away predators, you lose one of the factors keeping an ecosystem in balance.”
An ecosystem is a community of living things and the world they live in. Rainforests, oceans and cities are all ecosystems. Each ecosystem can support only so many animals. The maximum number it can handle is its carrying capacity.
Let’s say we have a super simple ecosystem of peacocks and jaguars. It can support 100 peacocks and 10 jaguars. The peacock population won’t get too big partly because jaguars gobble them up.
If jaguars vanish from our ecosystem, the peacock population may boom at first. Now there are 150 peacocks running around. But the ecosystem only has food for 100 peacocks. They’ll also start running out of space. With too many peacocks living close together, diseases may spread more easily. As a group, our peacocks might fare worse with the predators gone.
Real ecosystems are complex. Lots of living things interact in different ways. Many animals, like our peacocks, are both predators and prey. One sign of a healthy ecosystem is its biodiversity. That means a rich variety of living things.
One reason scientists study predators is to help protect animals and ecosystems. King told me some animals are umbrella species. That’s an animal — like the jaguar — that needs lots of room and prey to have a healthy life. If experts protect the jaguar’s ecosystem, that may help other animals that live there, too.
King told me kids can help protect animals and ecosystems, too. Start with small, meaningful actions like putting out bird feeders or growing native plants.
Have a question? Ask Dr. Universe, WSU’s resident science cat and writer, by email at Dr.Universe@wsu.edu.
