Scent of the enemy: behavioural responses to predator faecal odour in the fowl

Chemical communication is used by diverse organisms in a variety of contexts and can have strong fitness consequences for the individuals involved. However, despite the extensive use of birds as models for many research areas in biology, avian olfaction has been poorly investigated. Studies on bird species that lack well-developed olfactory organs and those investigating responses to predator odours are particularly scarce. We investigated behavioural responses of the domestic fowl, Gallus gallus domesticus, a ground-living species with intermediate olfactory bulb size, to several predator and nonpredator faecal odours. We found that the birds spent less time foraging and were more vigilant when exposed to predator faecal odour compared with nonpredator faecal odour. Individuals showed a similar response when exposed to increased amounts of faeces. Taken together, our results demonstrate that domestic fowl can distinguish between herbivore and predator faecal odour, and respond to predator olfactory cues alone, without prior experience. Our results have implications for the understanding of predator–prey interactions and responses to olfactory cues in general, and for chemical communication in avian species more specifically.