Eat rat mice

Mice spy on rats through their tears

When you're prey, it pays to spy on your hunters.

Researchers have demonstrated in a new study that mice can “spy on” the pheromones that rats use to communicate. The study, led by Kazushige Touhara of the University of Tokyo, identified a protein in the tear fluid of male rats that acts as a sex attractant for other rats, but acts as a warning sign in mice.

When male rats brush themselves, they spread their tears all over their bodies, enveloping themselves in the chemical signals of the liquid. When the rodents roam around, they leave an olfactory trail. Touhara and his team wanted to know whether mice can perceive the signals of rat tears.

For the experiments, the scientists used the usual laboratory species: the brown rat (Rattus novegicus) and the house mouse (Mus musculus) that share the living space of our cities.

Both rodents are omnivorous, but rats also have a tendency to kill and eat mice.

Scientists have already shown that mice avoid rat urine - a typical prey strategy. However, the current study is the first to show how a prey animal uses a specific pheromone from one of its hunters as an early warning system.


In the experiments, female rats spent more time examining cotton wool that had been treated with the pheromone ratCRP1 than with untreated cotton wool. Mice, on the other hand, spent less time on the treated cotton.

However, both species walked around less after contact with the pheromone. Further testing revealed that the heart rate and body temperature of the mice were still decreased even an hour after exposure.