Growing up with chronic traffic noise exposure leads to transient but not long-term noise tolerance in a songbird.

Noise pollution is on the rise worldwide. An unresolved issue regarding the mitigation of noise pollution is whether and at which timescales animals may adapt to noise pollution. Here, we tested whether continuous highway noise exposure perinatally and during juvenile development increased noise tolerance in a songbird, the zebra finch (Taeniopygia castanotis). Breeding pairs were exposed to highway noise recordings from pre-egg-laying until their offspring reached subadulthood. Subsequently, offspring were tested for noise tolerance both as subadults and adults in a spatial preference test, where birds could choose to enter aviaries with different levels of highway noise. Unlike control birds that preferentially chose the quiet aviaries, noise-reared birds exhibited no spatial preferences for quiet in the first test. However, when the experimental birds were retested after two months without noise exposure, they now avoided the previously tolerated noise levels and preferred the quieter aviary. The increased noise tolerance observed directly after the release from the noise treatment was thus only transient. Growing up with chronic highway noise exposure did thus not increase subjects' noise tolerance, meaning that at least in this songbird species, adaptation to noise pollution is unlikely to arise on a developmental time scale.