Experimental playback of urban noise does not affect cognitive performance in captive Australian magpies

Abstract

Exposure of wildlife to anthropogenic noise is associated with an array of disruptive effects. Research on this topic has focused on the behavioural and physiological responses of animals to noise, with little work investigating potential links to cognitive function. Neurological processes that maintain cognitive performance can be impacted by stress and sleep disturbances. While sleep loss impairs cognitive performance in Australian magpies, it is unclear whether urban noise, which disrupts sleep, can impact cognition as well. To fill this gap in our understanding, we explored how environmentally relevant urban noise affected the performance of wild-caught, city-living Australian magpies (Gymnorhina tibicen tyrannica) on a battery of cognitive tasks that included associative and reversal learning, inhibitory control, and spatial memory. Birds were housed and tested in a standardised laboratory environment; sample sizes varied across tasks (n = 7 – 9 birds). Tests were conducted over four weeks, during which all magpies were exposed to both an urban noise playback and a quiet control. Birds were presented with the entire test battery twice: following exposure to, and in the absence of, an anthropogenic noise playback; however, tests were always performed without noise (playback muted during testing). Magpies performed similarly in both treatments on all four tasks. We also found that prior experience with the associative learning task had a strong effect on performance, with birds performing better on their second round of trials. Similar to previous findings on Australian magpies tested on the same tasks in the wild under noisy conditions, we could not find any disruptive effects on cognitive performance in a controlled experimental laboratory setting.