Invasive ant species has made life difficult for African savanna lions

In an article on science.org, author Sean Cummings writes on the vast and intricate African savanna, a peculiar ecological upheaval is unfolding, akin to a fusion of David and Goliath with a Rube Goldberg machine. This bizarre phenomenon is occurring in the grasslands of Kenya, where an invasive ant species has displaced a native insect crucial for protecting the region’s acacia trees. This displacement, in turn, has allowed elephants to overgraze these trees, leading to a denuded landscape. The consequences ripple further, impacting the hunting dynamics of lions.

 

To investigate, researchers set up study plots in the Ol Pejeta Conservancy in Kenya, monitoring landscape visibility, plains zebra (Equus quagga) population density, big-headed ant occurrence, and lion kills of zebras. The findings after three years of observation were remarkable. Elephants targeted and toppled trees lacking native ant protection up to seven times faster than those with ant defenders. As a result, tree and bush cover diminished significantly, making it challenging for lions to stalk and ambush zebras.

 

Unexpectedly, lion populations in the study area remained stable despite the reduced access to their primary prey. Lions adapted by diversifying their diet, with zebra kills accounting for only 42% of their hunting activity in 2020, compared to 67% in 2003. The lions increased their predation on African buffalo (Syncerus caffer), a more challenging prey.

 

The study underscores the interconnectedness of ecosystems and the intricate relationships between species. The displacement of one species, the native acacia ants, by invasive big-headed ants has set off a chain reaction, affecting plant life, herbivore behavior, and predator-prey dynamics. The study also raises questions about the long-term sustainability of the lions’ dietary shift and the potential cascading effects on buffalo populations and other aspects of the ecosystem.

 

In the broader context of ecological research, this study stands out for its holistic approach, integrating multiple facets of the ecosystem, from ant-plant mutualisms to predator-prey interactions. The complexity of these interactions emphasizes the importance of viewing ecosystems as interconnected webs, where changes in one element can reverberate across the entire system, influencing the behavior and dynamics of various species.