Tiny Ants and Big Lions
This is a story of how an invasive ant species is impacting Africa’s iconic predators.
A tiny ant is troubling the king of the jungle in Africa. Researchers have found that the big-headed ant is hurting lion populations in Kenya.
The data shows that this invasive ant species is driving down acacia tree numbers in Kenya’s Ol Pejeta Conservancy by up to 10-15%, according to a 2014 study published in Biological Conservation [1].
These invasive ants kill off the ants that normally protect acacia trees. With no protection, elephants are eating more acacia trees, reducing the forest cover that lions rely on. Lions use the plants to hide before ambushing zebras, their favorite meal. Less plants make it tough for them to hunt.
The introduction of big-headed ants also impacts the local ant ecosystem. According to a study of ant diversity in the Congo Basin, invasive species like the big-headed ant can decrease native ant abundance by up to 80% [2], which makes matters worse for a keystone species like the lion.
“These tiny invaders are stealthily tugging at the ties that bind an African ecosystem together, influencing who gets eaten and where,” explains study co-author Dr. Todd Palmer, an ecologist at the University of Florida.
Lions Hunting Harder
With acacia trees disappearing, lions struggle to catch zebras. So the lions have started hunting bigger, tougher buffalo instead. But with lions listed as vulnerable to extinction on the IUCN Red List [3], researchers worry their new hunting habits could further threaten the species.
“Nature can be ingenious as animals evolve solutions to challenges,” Palmer says. “However, we’re unsure of the long-term consequences of lions switching to tougher targets.” In simpler terms, he means “Animals can adapt when faced with changes, but we don’t know yet how switching prey might impact lions in the long run.”
Ants Undoing Mutualism
This situation shows how species depend on each other. Usually, acacias shelter ants, who then protect the trees from plant eaters – a system where everyone benefits. But the invading ants kill the tree’s defenders and allow elephants to eat the acacias.
“We discovered that these tiny ants act as extremely effective bodyguards, helping acacias remain in landscapes full of mega herbivores,” Palmer explains. “It’s the little things ruling the world.”
Solutions and Implications
So while they seem harmless to us, the influence of tiny ant invaders on Kenya’s icons hints at hidden harms unfolding globally. It’s a reminder that little things can tip nature’s balance in big ways.
Beyond revealing connections in nature, the research shows the harm invasive species can cause. Experts are now searching to find ways to help, like keeping elephants from acacia trees to give them time to regrow. They also plan to study how the lions’ new diet further alters the landscape and other species.
On a different note, the work highlights how subtle environmental changes build over decades, defying short-term monitoring.
The 30-year project also used old-fashioned fieldwork, proving lasting value in on-site research despite new technologies. “Modern technology enables rapid big data collection,” Palmer states. “Yet this research stemmed from 30 years of old-fashioned fieldwork – highlighting the ongoing value of on-the-ground science.”
So while tiny, these ants may destabilize ecosystems globally. It’s a reminder of how small things can change nature in big ways.
Sources:
[1] Biological Conservation, 2014 [2] Biodiversity Conservation, 2012
[3] IUCN Red List
Journal Reference:
1. Douglas N. Kamaru, Todd M. Palmer, Corinna Riginos, Adam T. Ford, Jayne Belnap, Robert M. Chira, John M. Githaiga, Benard C. Gituku, Brandon R. Hays, Cyrus M. Kavwele, Alfred K. Kibungei, Clayton T. Lamb, Nelly J. Maiyo, Patrick D. Milligan, Samuel Mutisya, Caroline C. Ng’weno, Michael Ogutu, Alejandro G. Pietrek, Brendon T. Wildt, Jacob R. Goheen. Disruption of an ant-plant mutualism shapes interactions between lions and their primary prey. Science, 2024; 383 (6681): 433 DOI: 10.1126/science.adg1464
