Higher noise levels increase activity during the day and change the nocturnal habits of zoo-housed crab-eating foxes (Cerdocyon thous)

Abstract

The presence of visitors in zoos is commonly associated with higher noise levels, which have been correlated with increases in animals’ aggressive and stereotyped behaviours. We tested the effect of noise on the behaviour of six crab-eating foxes (Cerdocyon thous) - nocturnal canids - housed in four zoos in the São Paulo State countryside in Brazil in 2017. We tested the following hypotheses: (1) the presence of visitors increases the levels of noise; (2) higher noise levels affect the behaviour of the animals. We recorded the duration of the animals’ behaviours and the levels of noise (LAeq and LApeak) on days without visitors (Mondays) and with visitors (Saturdays and Sundays), as well as the duration of behaviours on the nights following these days. On days with higher noise levels, we recorded a higher duration of foraging and maintenance behaviours (e.g., yawning, sneezing, defecating, urinating, vocalising, stretching paws, and shaking body), and a lower duration of exploration. During the nights after days with high noise levels, there was a decrease in the duration of vigilance. Such changes in the behaviour of a nocturnal species point to a reversal of its natural habits, i.e., increasing activity during the day and reducing it at night. These effects are possibly connected to acoustic stress, which may reduce welfare, and suggest the need for better noise control in zoos.