In the vast expanse of East Africa’s savannas, lions have traditionally reigned as top predators, dominating the food web with their formidable presence. However, an unexpected and diminutive adversary has emerged, putting the majestic felines at risk—tiny invasive ants. These ants, no larger than a hollowed-out sesame seed, are orchestrating a chain reaction that could potentially reshape the entire African landscape, according to a study led by conservation biologist Douglas Kamaru from the University of Wyoming.
The culprit behind this ecological disruption is the big-headed ant. Originally described in the 18th century on the Indian Ocean island of Mauritius, these ants have hitchhiked around the world on human ships, gaining notoriety for infesting ceilings and excavating tile floors. In Kenya’s Laikipia County, the ants form supercolonies at the base of whistling-thorn acacias, climbing up to prey on native acacia ants. This predatory behavior initiates a domino effect, impacting the symbiotic relationship between the acacias and native ants, known as their “bodyguards.”
The native ants play a crucial role in defending the whistling-thorn trees from the most significant threat they face—elephants. Native acacia ants deter elephants from voraciously consuming the trees, maintaining the delicate balance of the ecosystem. However, big-headed ants offer no such protection, leading to a five to seven times increase in damage inflicted by elephants on whistling-thorn trees in invaded regions.
As a result, the once-thriving savanna transforms into an almost open grassland, with implications for the survival strategies of the resident wildlife. Zebras, now endowed with increased visibility in the absence of obstructing trees, experience higher survival rates, nearly tripling in regions invaded by big-headed ants. Lions, struggling to maintain their preferred prey, zebras, are compelled to adapt, resorting to buffalo as an alternative.
While lions in big-headed ant territories are still successfully hunting zebras and supplementing their diet with buffalo, concerns arise regarding the sustainability of this shift. If the invasive ants continue their relentless advance, the zebras may become even more elusive, potentially pushing lions to the brink of starvation or forcing them to find alternative prey.
The study highlights the intricate interplay within ecosystems and underscores the profound impact that seemingly insignificant creatures, like big-headed ants, can have on entire communities. The lions and ants saga serves as a cautionary tale of the far-reaching consequences of human-induced disruptions in delicate habitats. As the savanna grapples with threats like poaching, human development, and climate change, invasive species such as these ants add another layer of complexity to an already challenging narrative. The story of East Africa’s savannas becomes a vivid illustration of the vulnerability of ecosystems to unforeseen cascades, with humans playing a recurring role in reshaping the narrative.