Anthropogenic noise impairs foraging for cryptic prey via cross-sensory interference

Anthropogenic noise levels are globally rising with profound impacts on
ecosystems and the species that live in them. Masking or distraction by
noise can interfere with relevant sounds and thereby impact ecological
interactions between individuals of the same or different
species.  Predator-prey dynamics are particularly likely
to be influenced by rising noise levels, with important population- and
community-level consequences, as species may differentially adapt to noise
disturbance. Acoustic noise can, however, also impair the use of visual
information by animals through the process of cross-sensory interference,
possibly impacting species interactions that have so far been largely
ignored by noise impact studies. Here we assessed how noise affected the
performance of Great tit (Parus major) foraging on cryptic
prey. Birds trained individually to search for paper
moths differing in the level of camouflage with the test
background were tested in the presence and absence of
noise. We found that noise significantly increased approach and attack
latencies, but that the effect depended on the level of crypsis. Noise
increased latencies for cryptic prey targets, but not for conspicuous and
colour-matched prey targets. Our results show that noise can interfere
with the processing of visual information, particularly in difficult tasks
such as separating objects from a similar looking background. These
results have important ecological and evolutionary implications as they
demonstrate how globally rising anthropogenic noise levels can influence
the arms race between predators and prey across sensory domains.