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If you鈥檙e a rabbit, it鈥檚 important to recognise when predators are around. It鈥檚 even more useful to know if these predators are eating your friends. New research suggests that rabbits can do the latter聽by detecting the scent of other, now-digested rabbits in predator scat.

European rabbits are particularly popular targets for predators 鈥� more than 30 species will eat them, says Jos茅 Guerrero-Casado at the University of Cordoba, Spain.

To cope with the constant threat, rabbits have evolved an impressive ability to recognise the scent of a predator that might want to eat a bunny. But Guerrero-Casado and his colleagues wondered if rabbits could identify the scent of a predator that already had.

鈥淭he recognition of [other rabbits] in the predator scats would allow rabbits to avoid those areas with higher risk, feeding in other areas with a lower risk of being predated,鈥� explains Guerrero-Casado.

Smell test

The researchers ran an experiment on three plots of land spread out across the Spanish countryside. One plot was sprayed daily with the smelly essence extracted from the scat of ferrets on a beef-based diet. Another plot was sprayed with the scat odour from ferrets on a rabbit-based diet. The third was sprayed with water as a control. Every few days, the team counted the rabbit pellets left behind on the plots and used the number as an indicator of how often rabbits were visiting the plots to feed.

There were fewer pellets in the plots sprayed with rabbit-based scat odour than in those sprayed with the beef-based scat odour, suggesting the rabbits were avoiding places where it appeared other rabbits were being eaten.

鈥淣atural selection has provided animals with mechanisms that enable them to detect predators before being attacked, and this is a new mechanism; less studied, but with great advantages,鈥� says Guerrero-Casado. It might not be unique to rabbits: that kangaroos avoid areas scattered with tiger faeces if the tigers have been fed kangaroo. Goats will also avoid areas scattered with the faeces of goat-fed tigers.

Guerrero-Casado says the next steps will entail investigating how the rabbits manage to isolate their once-hopping brethren鈥檚 scent within the droppings, and if the type of predator involved modifies the manure鈥檚 miasma.