Grau, C., Leclercq, J., Descout, E. et al. 2019. Ethanol and a chemical from fox faeces modulate exploratory behaviour in laboratory mice. Applied Animal Behaviour Science 213, 117-123.

Mice are macrosmatic animals that use olfaction as their main source of information to increase fitness; they process predator cues to assess risk, and plants and fruit cues to find nutritional resources and assess their quality or toxicity. In this study, we examined the effects of ethanol as an olfactory stimulus related to fruit rotting, against 2,4,5-trimethylthiazoline (TMT, a fox faeces compound), its native origin, the fox faeces and a negative control on avoidance, locomotor activity, and stress related behaviour, measured by the production of faecal boli. Our results showed that mice clearly avoided ethanol (P=<0.0001) and decreased their locomotor activity (P = 0.0076) when ethanol was present. The molecule 2,4,5-trimethylthiazoline (TMT), was the most avoided (P=<0.0001) and showed the lowest locomotor activity (P = 0.0004). Both treatments, ethanol (P = 0.0348) and TMT (P = 0.0084) increased the number of faecal boli. The clear avoidance and behavioural effects of ethanol in mice have direct implications in laboratory animal research, where it is used widely. This avoidance effect could elicit stressful situations and modify behavioural and physiological responses in mice housed in research facilities. In addition, this avoidance could be used as a non-lethal, inexpensive and non-toxic tool in rodent pest management. To explain these results, we suggest ethanol as a probable cue for fruit ripening, in the wild, this chemical cue could convey primordial information about the ripening state of fruits, allowing animals to avoid over-ripe, unhealthy fruits.