Noise influences the acoustic behavior of killer whales, Orcinus orca, in Iceland

Increases in underwater noise due to anthropogenic activities have the potential to negatively affect cetaceans. Here, effects of increases in ocean background noise on the vocal behavior of killer whales were investigated. The study tested whether ambient noise levels affected time and frequency characteristics of the fundamental contour of killer whale calls and, if so, which noise level metrics were associated with these changes. Sound recordings were made with a moored autonomous recorder in Vestmannaeyjar, Iceland, where large numbers of killer whales feed on the Icelandic stock of summer-spawning herring. Calls were automatically detected in a 3-month recording. Seven call parameters of high-quality calls were measured in a data subset. Background noise during these calls was quantified in terms of broadband level and third octave band levels (TOLs). Broadband level was positively related to minimum, center and maximum frequency of the calls and negatively to their duration and average slope. With one exception, the TOLs did not significantly explain variations in the call parameters. These results highlight the need for killer whales to vocally compensate for changes in their environment, which has relevance in the context of the projected increases in anthropogenic activity due to warming of the Arctic.Increases in underwater noise due to anthropogenic activities have the potential to negatively affect cetaceans. Here, effects of increases in ocean background noise on the vocal behavior of killer whales were investigated. The study tested whether ambient noise levels affected time and frequency characteristics of the fundamental contour of killer whale calls and, if so, which noise level metrics were associated with these changes. Sound recordings were made with a moored autonomous recorder in Vestmannaeyjar, Iceland, where large numbers of killer whales feed on the Icelandic stock of summer-spawning herring. Calls were automatically detected in a 3-month recording. Seven call parameters of high-quality calls were measured in a data subset. Background noise during these calls was quantified in terms of broadband level and third octave band levels (TOLs). Broadband level was positively related to minimum, center and maximum frequency of the calls and negatively to their duration and average slope. With o...