Behaviour 2019
Variable and consistent traffic noise negatively affect the sleep behavior of a free-living songbird
Melissa L Grunst, Andrea S Grunst, Rianne Pinxten, Marcel Eens. University of Antwerp, Antwerp, Antwerpen, Belgium

Anthropogenic noise has wide-reaching, well-documented effects on animal behavior. However, research effort has focused on the waking phase. Sleep plays vital functions in processes such as cellular repair. Thus, understanding effects of noise on sleep is a critical research objective. Whether different noise regimes exert distinct effects on behavior also remains poorly understood, as does intraspecific variation in noise sensitivity. We used a field experiment to evaluate whether increasing the temporal variability and amplitude of traffic noise increased deleterious effects on sleep in free-living great tits (Parus major).  We found strong negative effects of traffic noise on sleep. There was some support for a stronger effect of more variable noise, and relative to lower amplitude noise, higher amplitude noise resulted in less and more fragmented sleep. Effects of noise on sleep duration were stronger in older adults, and repeatable variation existed in individual responses. We demonstrate that anthropogenic noise can have strong, individual-specific, effects on sleep in free-living animals, which may have cascading effects on waking behavior, physiology and fitness.