Why Are Lions Catching Fewer Zebras? Ants

Feb 5, 2024

Scientists in Africa wanted to know why lions aren't catching as many zebras. They found a fascinating reason.

It's ants.

“I was stunned,” said Todd Palmer. He's a biologist at the University of Florida. His team noticed that lions in certain regions were catching only a third of the zebras that other lions did. Then the researchers traced a line of connections, known as "mutualism," all the way to big-headed ants. That's an invasive species. Here’s the breakdown:

 •  Acacia ants are native to the acacia trees that grow throughout eastern Africa. The trees provide them with food and shelter. In return, the ants protect the trees.

 •  Big-headed ants invade the acacia groves. They drive out the smaller acacia ants.

 •  Elephants stroll up to munch on the acacia trees.

 •  Normally, acacia ants would attack the elephants. They swarm them and drive them away. But big-headed ants leave the elephants alone.

 •  Elephants eat all the leaves off the acacia trees, killing them.

 •  Lions, which rely on acacia leaves for cover as they hunt, are exposed.

 •  Zebras can now see hunting lions. They escape before they’re caught.

The big-headed ants are a big problem, too. “In invaded areas, elephants browse and break trees at five to seven times the rate of that in uninvaded areas,” Palmer notes in the study, published recently in the journal Science.

And starving lions, researchers say, are just the beginning. “If the invasion continues, more and more acacia trees will be lost,” Palmer told The Guardian. That would rob other species, like rhinos and giraffes, of an important food supply.

GIF courtesy Planckendael on GIPHY.

Reflect: How might unexpected changes in one part of nature have ripple effects on the entire ecosystem?

Which of the following ideas is highlighted by the author throughout the story? (Common Core RI.5.3; RI.6.3)
a. the natural behavior of lions in hunting zebras
b. the essential role of elephants in maintaining ecosystem balance
c. the impact of invasive big-headed ants on the acacia tree ecosystem
d. the ability of acacia ants to coexist with other species in eastern Africa
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