Experimental noise and light pollution alter prey detection in a nocturnal bird of prey

Urban expansion has led to ever-increasing noise and light pollution,
which impair the audio-visual perception of wild animals and drive changes
in key activities and behaviours. Nocturnal predators may be
especially affected in detecting prey, with potentially dramatic
consequences for their fitness. However, the combined effects of noise and
light pollution on predator performance are still mostly unstudied. We
experimentally exposed Tawny Owls (Strix aluco), nocturnal acoustic
raptors, to traffic noise and artificial light. We provided both visual
and acoustic prey cues to assess potential non-additive effects among
multiple sensory stressors on the ability to detect prey. We found that,
in control conditions, owls responded equally to both acoustic and visual
prey cues. In contrast, noise and light individually decreased owls’
ability to locate acoustic, but not visual, prey cues. When owls were
exposed to noise and light combined also visual detection worsened, but
not beyond the additive expectation. Conversely, the presence of light
seemingly buffered the negative impact of noise on acoustic detection,
suggesting an antagonistic interaction. Our findings show that both
anthropogenic noise and light affect the hunting behaviour of a nocturnal
avian predator, but with a stronger effect on acoustic than visual
detection, suggesting that the magnitude of their disruptive impact might
depend on the type of prey cue. This implies that sensory pollution might
lead to increased reliance on sight-oriented hunting strategies.
Importantly, our study shows that the co-occurrence of noise and light can
have complex and unexpected impacts on behaviour, underscoring the
importance of examining sensory pollution in a multimodal context.