01876nas a2200193 4500008004100000245012500041210006900166520117200235653003101407653002001438653001901458653001801477100002901495700002601524700002701550700001901577700002001596856006601616 2021 eng d00aLimited vocal compensation for elevated ambient noise in bearded seals: implications for an industrializing Arctic Ocean0 aLimited vocal compensation for elevated ambient noise in bearded3 a

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.

10abearded seal advertisement10achanging Arctic10aLombard effect10anoise impacts1 aFournet, Michelle, E. H.1 aSilvestri, Margherita1 aClark, Christopher, W.1 aKlinck, Holger1 aRice, Aaron, N. uhttps://royalsocietypublishing.org/doi/10.1098/rspb.2020.271201746nas a2200121 4500008004100000245013300041210006900174520120600243653005701449100002701506700002501533856006601558 2004 eng d00aAcoustic monitoring on a humpback whale ( Megaptera novaeangliae) feeding ground shows continual singing into late spring0 aAcoustic monitoring on a humpback whale iMegaptera novaeangliaei3 a

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' 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.

10ahumpback whale; song; mating systems; North Atlantic1 aClark, Christopher, W.1 aClapham, Phillip, J. uhttps://royalsocietypublishing.org/doi/10.1098/rspb.2004.2699