@article {58417, title = {Limited vocal compensation for elevated ambient noise in bearded seals: implications for an industrializing Arctic Ocean}, year = {2021}, abstract = {

Vocalizing animals have several strategies to compensate for elevated ambient noise. These behaviours evolved under historical conditions, but compensation limits are quickly being reached in the Anthropocene. Acoustic communication is essential to male bearded seals that vocalize for courtship and defending territories. As Arctic sea ice declines, industrial activities and associated anthropogenic noise are likely to increase. Documenting how seals respond to noise and identifying naturally occurring behavioural thresholds would indicate either their resilience or vulnerability to changing soundscapes. We investigated whether male bearded seals modified call amplitudes in response to changing ambient noise levels. Vocalizing seals increased their call amplitudes until ambient noise levels reached an observable threshold, above which call source levels stopped increasing. The presence of a threshold indicates limited noise compensation for seals, which still renders them vulnerable to acoustic masking of vocal signals. This behavioural threshold and response to noise is critical for developing management plans for an industrializing Arctic.

}, keywords = {bearded seal advertisement, changing Arctic, Lombard effect, noise impacts}, doi = {10.1098/rspb.2020.2712}, url = {https://royalsocietypublishing.org/doi/10.1098/rspb.2020.2712}, author = {Fournet, Michelle E. H. and Silvestri, Margherita and Clark, Christopher W. and Klinck, Holger and Rice, Aaron N.} } @article {58226, title = {Acoustic monitoring on a humpback whale ( Megaptera novaeangliae) feeding ground shows continual singing into late spring}, year = {2004}, abstract = {

Singing by males is a major feature of the mating system of humpback whales, Megaptera novaeangliae (Borowski). Although a few songs have been opportunistically recorded on the whales\&$\#$39; high\–latitude feeding grounds, singing in these regions was thought to be only sporadic. We report results from the first continuous acoustic monitoring of a humpback whale feeding ground (off Cape Cod, MA, USA) in spring. Using autonomous sea\–floor recording systems, we found singing on a daily basis over the entire 25 day monitoring period, from 14 May to 7 June 2000. For much of the period, song was recorded 24 h per day. These results, combined with evidence for aseasonal conceptions in whaling catch data, suggest that the humpback whale breeding season should no longer be considered as confined to lower\–latitude regions in winter. Rather, we suggest breeding extends geographically and temporally onto feeding grounds into at least spring and early summer. Singing at these times represents either low\–cost opportunistic advertising by (perhaps relatively few) males to court females that failed to conceive during the winter, and/or possibly an intrasexual display.

}, keywords = {humpback whale; song; mating systems; North Atlantic}, doi = {10.1098/rspb.2004.2699}, url = {https://royalsocietypublishing.org/doi/10.1098/rspb.2004.2699}, author = {Clark, Christopher W. and Clapham, Phillip J.} }