THIS puts the story of David and Goliath into perspective. Tiny red fire ants in Argentina target fearsome caimans, with as many as one in four of the crocodilian's babies falling prey to insect attackers.
The ants colonise more than half the broad-snouted caiman nests, where the fermenting bedding material provides the humidity and warmth the insects' eggs and larvae need.
They bite the caiman mum, forcing her to abandon the nest. Then, when the young start to hatch, the ants sneak inside the eggs to kill the babies and eat them. It seems that 26 per cent of broad-snouted caiman babies in a breeding season could die by red fire ant predation (Journal of Herpetology, doi.org/266).
The baby caimans are defenceless against an army of the little red monsters. "It is not one caiman against one red fire ant – it is one caiman against about 100,000 fire ants," says Carlos Ignacio Piña of the Laboratory of Applied Zoology in Santa Fe, Argentina, an author of the study. "There are so many fire ants that the baby caiman starts to shake like crazy, trying to get released."
The proportion of killed caimans is somewhat disturbing, but not crazily high, says Craig Allen from the University of Nebraska-Lincoln. It is of no immediate concern to caiman populations in South America because the ants and caimans co-evolved there, and natural red fire ant predators, such as the decapitating fly, help keep the ants in check.
Elsewhere though, these invasive ants could wreak havoc, partially because their natural predators are absent. Allen has previously found that they can kill 70 per cent of turtle hatchlings in Florida. In the US, they have also been caught munching on snakes, lizards, birds and even deer fawns, who freeze when in danger, giving ants time to attack.
This article appeared in print under the headline "Croc and awe: Fire ants eat quarter of baby caimans"
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