Zebras saved by ants

Did you see the recently reported story of fewer zebras being eaten by lions in Kenya thanks to invasive ants?

Normally, the local ants occupy trees and ward off leaf eating animals such as elephants by biting them.
This in turn gives the lions cover to stalk their prey.

However, an invasion by the big-headed ant species disrupted a mutualism between native ants and the region’s thorny acacia trees, in which the native ants protected the trees from grazers in exchange for a place to live.

When the invasive ants pushed out the native ants, the trees were left vulnerable to overgrazing by elephants, who browsed and broke trees at five to seven times the rate in areas with invasive ants compared to areas without the invaders.

The result was a much more open landscape, where lions were left without hiding places to observe and stalk their preferred prey of zebra.

The lions responded by shifting their prey to include more African buffalo. From 2003 to 2020, the proportion of zebra kills made by lions dropped from 67% to 42%, while the proportion of buffalo kills rose from 0% to 42%. The study offers an important glimpse at how disruption of a mutualism can have reverberations throughout an ecosystem.