01993nas a2200145   4500008004100000245011600041210006900157520145700226100002601683700002001709700002001729700002401749700002301773856005101796       2019                        eng d00aHigh-amplitude vocalizations of male northern elephant seals and associated ambient noise on a breeding rookery0 aHighamplitude vocalizations of male northern elephant seals and 3 a<p>Northern elephant seals (Mirounga angustirostris) are massive, land-breeding marine mammals that produce loud, stereotyped calls during annual breeding seasons. To determine vocalization source levels emitted by competing males on a mainland breeding rookery, aerial calls were measured on-axis at 1&thinsp;m from adult males using three different sound pressure level metrics. Time-averaged (1 min) ambient noise was also measured under variable environmental and social conditions. Results indicate that male northern elephant seals emit high amplitude airborne calls with little variation in call amplitude. Mean source levels ranged from 98 to 114&thinsp;dB re: 20 &mu;Pa [root-mean-square (rms) -fast], 102&ndash;116&thinsp;dB re: 20 &mu;Pa (rms-impulse), and 120&ndash;131&thinsp;dB re: 20 &mu;Pa (peak) and average standard deviations for all metrics were &lt;2.3&thinsp;dB. Further, these seal rookeries exhibit high variability in ambient noise (in terms of both spectrum and amplitude) from biotic and environmental sources. Finally, males sampled did not adjust call amplitude to compensate for higher background noise levels and thus did not exhibit a Lombard effect. These findings reinforce the view that the remarkable vocalizations of male northern elephant seals serve as rigid and powerful signals that convey individual identity within noisy breeding colonies rather than as honest indicators of size, status, or motivation.</p>
1 aSouthall, Brandon, L.1 aCasey, Caroline1 aHolt, Marla, M.1 aInsley, Stephen, J.1 aReichmuth, Colleen  uhttp://asa.scitation.org/doi/10.1121/1.5139422