Lions like to eat zebras, zebras like grass, elephants like acacia trees, and an invasive ant changes it all. The story unfolds in a study by Douglas Makaru and 19 colleagues.
A classic story in ecology is that ants living on acacia trees in woodlands of East Africa protect trees from browsing elephants. Their stings are a great deterrent. In line with modest rainfall, the trees have a modest presence in the savanna, interspersed with grasses and small forbs.
Now, the invasive big-headed ant has taken over many acacias in Kenya. These ants don’t protect the acacias, so that elephants are browsing and breaking the trees at 5 to 7 times the old rate. That loss of trees increases the abundance of grass. Zebras thrive. On one hand, that’s good for lions, for whom zebras are more than half of their prey outside these areas. On the other hand, lions are more visible to zebras in the more open landscape; their success rate in hunting zebras has fallen.
Lions have shifted more to hunting the very dangerous Cape buffalo over 18 years. Lou Ellen and I have seen Cape buffalo too close for comfort. Lions feel the same, perhaps; they get killed by buffalo. So far, there’s been no significant fall in the number of lions or zebras, rather a surprise if it continues.
This has been an outreach activity of the Las Cruces Academy, viewable at GreatSchools.org.
Story from Science, 26 Jan. ‘24
