“How ants persuaded lions to eat buffalo” sounds like a story out of a children’s book. However, reality is often stranger than fiction, as we all know, and this is a case in point. It is also yet another example of the unforeseen consequences of tinkering with nature – humans seem particularly good at doing this without thinking beyond the “ends of their noses”.
In an area of Kenya, not far from the mountain that gives the country its name, an invasive species of ant is upsetting the predator/prey balance on the savanna. “Big-headed Ants”, the invasive species (no-one seems to know where they came from) have gradually been replacing the native “Acacia Ants”.
Both species live in the “Whistling-thorn” trees, which are native to the area.
Douglas Kamaru, a Kenyan biologist, and his colleagues, have reported in Science magazine that the big-headed ant invasion has triggered a convoluted chain of consequences which has helped the area’s zebras at the expense of the area’s buffalo – the phenomenon is known as “trophic cascade”.
I am reminded of the story I published some time ago of how the re-introduction of wolves into Yellowstone National Park changed the course of the rivers: A similar convoluted series of consequences of that re-introduction.
The acacia ants and the whistling-thorn trees have evolved together: The trees provide the ants with shelter and food, in the form of large, hollow thorns into which they secrete nutritious nectar, which attracts the ants. The ants, meanwhile, protect the trees by seeing-off the chief threat to them, the local elephants, which are not keen to browse trees crawling with biting insects.
However, the big-headed ants are not so good at keeping the elephants at bay. The pachyderms move in and munch the trees, removing much of the area’s cover. That discombobulates the local lions, which often use the trees as cover when hunting zebra. To compensate, the lions have switched to hunting buffalo, which are more dangerous, but far less fleet of foot, thus reducing the amount of stealth the lions need to employ – they don’t need as much tree cover to be successful in their hunts.
In areas invaded by big-headed ants, elephants browse and break trees five to seven times more often than in areas dominated by acacia ants. In areas uninvaded by big-headed ants, zebra kills by lions are almost three-times as frequent as those in big-headed-ant-dominant areas.
Between 2003 and 2020, as big-headed ants have spread, the proportion of local lion kills where the victim was a zebra fell from 67% to 42%. The proportion of buffalo kills over the same time period went from zero to 42%.
Obviously, ants persuaded lions to eat buffalo instead of their former target of zebra.
This is obviously a very interesting story that few would have put together in all its consequential steps. Douglas Kamaru should be congratulated on his diligence. However, we should also be more thankful to him for giving us a concrete warning about the ripple effect of many of our knee-jerk reactions to the problems of climate change and many other aspects of our effect on the environment. We arrogantly think we know better/best, whereas we often create far more problems with our naïve decisions than we solve. Taking our time to consider overall consequences is not something we are good at, but it is something that can cause the disintegration of our environment and, consequently, our ability to survive at all.
We have become accustomed to sensational headlines. Indeed, we have become addicted to them, led by a media system that places more importance on sensationalism than it does on content or integrity. Maybe we can use that flaw for the greater good. “How ants persuaded lions to eat buffalo” is a great example. It immediately caught my attention and, if I may be presumptuous, it caught your attention as well.