Easy prey: The fearful cries of babies attract crocodiles

Crocodiles can sense the distress of the cries of baby monkeys or young humans—and they’re especially attracted to them. At the Agadir Zoo in Morocco, researchers from Lyon played samples of the cry sounds of young humans, bonobos and chimpanzees to Nile crocodiles and observed their movements in the crocodile’s tank. The study has been published in the journal “Proceedings of the Royal Society B” published.

Reptiles are particularly sensitive to extreme fear

The researchers found that “crocodiles perfectly detect distress in the cries of young monkeys or humans, but also that reptiles react more strongly the more distress present in the cries,” said study co-author, bioacoustician Nicholas Grimoult. If the cries of small animals and people seemed desperate, the reptiles were especially attracted to them.

The harsh sound stimulates the animals

Originally, the researchers wanted to investigate the universality of stress traits in animal calls. However, they found that some vocal parameters were more relevant to crocodiles than to humans: “Crocodiles orient themselves according to criteria of ‘roughness’ and ‘disorder’ in a cry,” Grimoult explained, while humans react to pitch.

With a little movement, crocodiles become easy prey

For the researcher, the behavior can be explained by the fact that, as cold-blooded animals, crocodiles are very economical in their movements. This is how they specifically interact with potential prey animals that already seem vulnerable. Grimolt: “The more distress the animal is, the easier the prey.”