Crocodiles Recognize Sound of Young Animal Crying in Distress, Sensing the Baby As Potential Meal

Crocodiles are alarmingly accustomed to the cries of human babies, so they may even be better at recognizing the distress in infants than people do.

Unique Attraction to Cries

A study was conducted by a group of researchers where they tested the reaction of Nile crocodiles to various cries. They visited the voracious reptiles at a Moroccan zoo and placed remote-controlled loudspeakers on the outdoor ponds.

The researchers then played recordings of cries coming from the loudspeakers placed near the groups of up to 25 Nile crocodiles. The recordings include cries from chimpanzees or bonobo infants calling to their mothers. Other cries were from human babies recorded either at bath time or while at the doctor's clinic for a vaccination.

Almost all the recordings triggered the crocodiles to move toward the loudspeaker and look for the source. For instance, upon hearing the sound of human babies getting the vaccines, half of the crocodiles in a group responded.

The reptiles were heavily attracted to the cries, especially the shrieks indicating more distress. The researchers believe that crocodiles were likely drawn to infant wails because they signal that an easy meal is available nearby. The opposite may be true in some cases, and the ferocious animal may be trying to help.

According to study author Nicolas Grimault, bioacoustic research director at the French National Centre for Scientific Research, this reaction shows the nature of distress as something shared by animals, even if they come from distant species. He also added that crying appears to be a kind of emotional communication between humans and crocodiles.

However, the sex of the crocodiles was not considered in the study since the researchers could not identify which of them were male or female. Determining whether male or female crocodiles have more tendency to move toward a crying speaker can better clarify whether the reptiles were trying to hurt or help.

Cognitive scientist Piera Filippi from the University of Zurich described the study result as something that speaks to the factors that could drive animal survival. This means that if the Nile crocodiles have evolved to listen to the sound of scared infant animals, then this skill can help them stay fed and alive.

What is a Nile Crocodile?

Nile crocodile (Crocodylus niloticus) is the largest crocodilian species in Africa which can grow up to 25 feet long and weigh up to 1,650 pounds. They thrive in the sub-Saharan region, the Nile Basin, and in the fresh water in Madagascar.

Nile crocodiles feed mainly on fish but attack anything that crosses their path, such as birds, zebras, porcupines, and even other crocodiles. It can eat up to half its body weight at a single feeding.

This fearsome predator has the unusual characteristic of being a caring parent. While most reptiles lay their eggs somewhere and move on, the male and female Nile crocodiles guard their nests until the eggs completely hatch. Sometimes, they gently roll the eggs in their mouths to help their babies emerge from them.