Ants turn the animal world upside down

Small animals, big impact: An invasive ant species is spreading in Kenya – and making it more difficult for lions to hunt their favorite prey.

Bremen – “We often realize that it's the little things that rule the world,” says Todd Palmer. He is a researcher at the University of Florida and co-author of a study about a chain reaction in the Kenyan savanna ecosystem. The trigger is an invasive species of ant. Its influence has turned the animal world upside down and reconfigured predator-prey dynamics between iconic species, according to the research team in Trade magazine Science writes. This meant that even lions had to change their hunting strategy.

Researchers make important discovery: Invasive ants trigger a chain reaction

According to researchers led by Douglas Kamaru from the University of Wyoming, the chain reaction began like this: alien large-headed ants (Pheidole megacephala), also known as fat-headed ants, drove out the crematogaster ants native to the Kenyan savannah. These actually live in the thorns of flute acacias and protect them like bodyguards: If a herbivore wants to nibble on “their” tree, they pounce on it within seconds and bite painfully. Even elephants are deterred by this and therefore avoid the trees.

“To our great surprise, we found that these small ants are incredibly strong defenders and essentially stabilized the tree cover in these landscapes, allowing the acacia trees to survive in a place with so many large herbivorous mammals,” explained co-author Palmer. Unlike the Crematogaster ants, the fat-headed ants do not defend these trees.

Without the protective ants, elephants eat and break five to seven times more trees than before. According to the study, flute acacias represent more than 70 to nearly 100 percent of all woody stems in the region.

Invasive ants in Kenya: Lions have to change their hunting behavior

But to what extent does this have an influence on the hunting behavior of lions in the Kenyan savannah? It's quite simple: they actually use the privacy of the trees to inconspicuously stalk their prey – preferably plains zebras. Fewer trees also mean less success for the lions when hunting, because the zebras now have a better overview and can flee from their predators earlier.

As the research team reports, the number is Lions The number of zebras killed has fallen significantly due to the spread of big-headed ants. The lions have therefore changed their hunting behavior: they now increasingly rely on Cape buffalo for their diet. However, they are significantly larger and harder to capture than zebras.

“Nature is smart, and animals like lions tend to find solutions to problems they face,” Palmer says. So far, the lion population in the region has not yet decreased. “But we don’t yet know what could result from this profound change in the lions’ hunting strategy.” We want to continue to keep an eye on developments.

“Devastating effects”: Invasive ants now widespread

The large-headed ants have now spread from Australia, Madagascar and Africa via India to South and North America tagesschau.de reported. There, the invasive species causes considerable damage by forming super colonies and displacing native ant species.

“These tiny invasive ants appeared maybe 15 years ago and none of us noticed because they are not aggressive towards large animals, including humans. Now we see that they are changing the landscapes in very subtle ways, but with devastating effects,” write the researchers of the study in the Kenyan savannah. Because big-headed ants prefer a tropical climate, the invasive species has so far only played a minor role in Germany.

Last year, researchers described it as one of the worst invasive species Red fire ant, 88 nests of which have been discovered in Italy. The noble orb spider, known as the “false widow,” is also extremely invasive. In Brazil, biologists recently made a spectacular discovery: a giant anteater was spotted in the wild for the first time in more than 100 years. (ph/dpa)