The spread of big-headed ants in east Africa has disrupted the life of the African lion, forcing it to make fewer zebra kills and switch its prey, scientists have found.
The presence of the insects at the Ol Pejeta Conservancy in Kenya has changed the landscape of the area, impacting plants and animals throughout the ecosystem.
According to the study, big-headed ants – thought to be native to Mauritius but which have spread throughout much of the subtropical and tropical world – have “led to increased herbivory by elephants and ultimately a shift in lion prey species from zebra to buffalo” at the reserve.
“These tiny invaders are cryptically pulling on the ties that bind an African ecosystem together, determining who is eaten and where,” said Professor Todd Palmer, a co-author of the study.
The study, which spans research over three decades, showed the complex web of interactions among ants, trees, elephants, lions, zebras and buffalo in the local savanna.
The team of researchers from the University of Florida tracked the impact of the “tiny invaders” on the wildlife conservation area in Laikipia County by using hidden cameras, satellite-linked lion collars and statistical modelling.
They found the big-headed ants attacked native acacia ants, rendering whistling thorn trees in the area vulnerable to being eaten by elephants.
This resulted in landscapes with higher visibility, the researchers said, leading to “significantly less” zebra kills by lions which rely on the tree cover to stalk and hide before pouncing on their prey.
Instead, the iconic predator switched from hunting its preferred prey to buffalo – which are larger than zebras and hang out in groups.
“Oftentimes, we find it’s the little things that rule the world,” said Prof Palmer.
“These tiny invasive ants showed up maybe 15 years ago, and none of us noticed because they aren’t aggressive toward big critters, including people.
“We now see they are transforming landscapes in very subtle ways but with devastating effects.”
He continued: “Nature is clever, and critters like lions tend to find solutions to the problems they face.
“But we don’t yet know what could result from this profound switch in the lions’ hunting strategy. We are keenly interested in following up on this story.”
He added: “These ants are everywhere, especially in the tropics and subtropics.
“We are working with land managers to investigate interventions, including temporarily fencing out large herbivores, to minimise the impact of ant invaders on tree populations.”
The study, which Prof Palmer described as “born of driving around in Land Rovers in the mud for 30 years”, has been published in the journal, Science.