The tale of the ants who scared the elephants to help the lions catch the zebras may sound like a children's fairy tale, but it is a true story with an unhappy ending for the big cats. Lions in Kenya are being pushed closer to endangered situation because the acacia trees that they rely on for cover while hunting zebras are dying. leaving them nowhere to hide while hunting.
Scientists were surprised that acacia trees were able to grow fast in the Nature Conservancy in central Kenya, as there are so many leaf-eating mammals such as elephiants and giraffes that would normally eat up the tree leaves.
The acacias' secret weapon is a species of ant that lives in the tree. The trees are historically protected from leaf-eating animals by this species. In return for their home, the ants defend the trees from huge plant eaters, like elephants, giraffes, an arrangement ecologists call mutualism（共生）.
About 15 years ago, unnoticed by environmentalists, a new species of ant slipped into the region. It is thought that this invasive species, known as the big-headed ant, often found hidden in the wood used in construction, was brought to the area by human activity. These ants set about attacking and destroying the ants that used to defend the trees. The new ants do not make any effort to protect the trees, leaving the acacia trees defenceless. This has set off a chain of events, resulting in a shift in predator-prey（捕食者—猎物）behaviour that may further endanger populations of lions, researchers said. "The lions rely on the tree cover to hunt and hide before attacking zebras. Less tree cover means lions are not as successful at ambushing（伏击）their prey."
