In caves in Gabon, dwarf crocodiles have learned to take advantage of an unexpected food source: bats they can even catch by leaping.
These reptiles belong to the genus Osteolaemus, the African dwarf crocodiles. With an average length of around 1.5 meters, they are the smallest living crocodilians. They usually live in the forests and wetlands of West and Central Africa, where they hunt crabs, frogs, and other small animals.
An orange cave dwarf crocodile on the left, and a forest crocodile on the right.
Credit: Olivier Testa, CC BY-SA 3.0, via Wikimedia Commons
A population discovered in the Abanda caves in Gabon leads a very different existence. The animals spend much of their time underground, in cavities occupied by immense bat colonies. The ground there is covered with guano, and the environment differs greatly from the neighboring forest waterways.
While studying the stomach contents of live-caught crocodiles, researcher Matt Shirley found numerous bat remains. Direct observations then showed how the reptiles obtained this prey. At dusk, when bats leave the cave en masse, some collide and fall to the ground.
The crocodiles then wait for an opportunity to seize them. Even more surprisingly, some have been observed leaping into the air to catch a bat. This behavior takes advantage of an extremely abundant resource just a few meters from their resting place.
This diet could help explain why the crocodiles remain in such an unusual environment. Genetic analyses show that the cave population is distinct from the one living in the nearby forest. It is not yet considered a separate species, but prolonged isolation could increase its differences.
These animals also display a spectacular color. While dwarf crocodiles are normally very dark, some cave individuals turn orange. Researchers believe this color is not genetic: prolonged contact with acidic guano could gradually alter their skin.
This population demonstrates the dwarf crocodile's ability to adapt, but the species faces other pressures elsewhere in Africa. Forest destruction is reducing its habitats, and tens of thousands of individuals may be captured for their meat. Their elusive nature also makes populations difficult to count.