The impact of in-air noise on the behavior of harbor seals ( <i>Phoca vitulina</i> ) at the water’s surface

Pollution, such as in-air noise, is a threat to animals whose habitat heavily overlaps with areas of human development. The sensitive in-air hearing of harbor seals ( Phoca vitulina Linnaeus, 1758), a pinniped species, makes them particularly susceptible to anthropogenic noise. Hauled-out harbor seals alter their behavior in response to in-air noise. Yet, to our knowledge there has been no effort to establish whether a similar pattern occurs while seals are in the water with their head above the surface. To address this gap, we compared the number of surfaced seals and the duration of time they spent at the surface (surfacing duration) to in-air noise at the Bellingham Waterfront in Washington State, USA. We used generalized linear mixed models with a Bayesian framework to determine whether in-air noise predicted the number of seals and their surfacing durations. We found no relationship between in-air noise levels and the numbers of seals present at the waterfront or the surfacing durations. This suggests that the seals who frequent this site tolerate the local in-air noise levels. Given that the site is heavily used by humans, future work should examine if this tolerance puts seals at risk of harmful interactions with human activities.