02118nas a2200193 4500008004100000022002500041245011100066210006900177260001600246300000900262520146700271100002501738700002501763700002001788700002001808700002601828700001801854856005201872 2022 eng d a0952-4622, 2165-058600aIn-air acoustic repertoire and associated behaviour of wild juvenile crabeater seals during rehabilitation0 aInair acoustic repertoire and associated behaviour of wild juven cAug-18-2022 a1-233 a

In-air sounds of pinnipeds are important for interactions with conspecifics and threat displays. However, little is known about the in-air acoustic repertoire and associated behaviour of crabeater seals Lobodon carcinophaga. We investigated the in-air acoustic repertoire and associated behaviour of two male and one female wild juvenile crabeater seals that beached separately, and were rehabilitated in Durban and Gqeberha, South Africa. In-air sounds were visually identified and categorised into five classes validated via random forest model classification: brief, intermediate, and long moan calls, croaks, and hisses. Hisses were common (n = 25,105 sounds from 136 hrs of acoustic recordings) and detected during heightened arousal states and interactions with animal care staff and a conspecific. Furthermore, hisses were also recorded in low arousal states during exhalation. Moan calls (n = 241) were only detected from two of the three seals. During rehabilitation, the female seal ceased producing moan calls and later produced a series of croaks (n = 204). Acoustic characteristics of in-air moan calls differed from published underwater moan calls according to duration, minimum, and maximum frequencies, and pulse repetition rate. Our study shows that the in-air acoustic repertoire and associated behaviour of these Antarctic seals are dynamic, vary inter-individually and are context dependent.

1 aShabangu, Fannie, W.1 aHofmeyr, G., J. Greg1 aProbert, Rachel1 aConnan, Maëlle1 aBuhrmann, Corrine, A.1 aGridley, Tess uhttp://dx.doi.org/10.1080/09524622.2022.210814501876nas 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.2020.271202089nas a2200145 4500008004100000245010700041210006900148520147500217653001501692653002101707653002901728653002801757100002201785856013601807 2020 eng d00aObservations on mechanisms and phenomena underlying underwater and surface vocalisations of grey seals0 aObservations on mechanisms and phenomena underlying underwater a3 a

Air and water constitute acoustic propagation media with very different physical properties. Consequently, mechanisms for air- and water-borne sound generation observed in terrestrial and aquatic animals are also significantly different. Notwithstanding, some amphibious species are capable of making efficient use of their vocal tracts in both environments. The present study investi- gates such a phenomenon on the example of grey seals Halichoerus grypus. Grey seals vocalise both underwater and above the water surface emitting variety of sounds. Both kinds of vocalisations were recorded using microphones and hydrophones, and analysed for their acoustic parameters which could be related to the underlying generation mechanisms. Also, video with synchronised underwater audio recordings were captured, allowing to link the acoustic phe- nomena with specific behaviour of the animals. The vocalisations are categorised into three groups based on differences in acoustic characteristics. Temporal and spectral parameters of the sounds belonging to each group are determined and discussed in terms of potential underlying generation mechanisms. Based on the adopted criteria surface vocalisations do not constitute a separate group but are categorised together with other tonal sounds pro- duced underwater. Other two vocalisation groups include pulsed sounds with different bandwidths, duration times, repetition rates and associated behavioural signatures.

10aGrey seals10asound production10aunderwater vocalisations10avocalisation mechanisms1 aNowak, Lukasz, J. uhttps://www.tandfonline.com/doi/full/10.1080/09524622.2020.1851298https://www.tandfonline.com/doi/pdf/10.1080/09524622.2020.185129801979nas a2200205 4500008004100000245015500041210006900196520123200265653002701497653001801524653001901542653001001561653001801571100002501589700002901614700002401643700001901667700002101686856006601707 2020 eng d00aAcoustically advertising male harbour seals in southeast Alaska do not make biologically relevant acoustic adjustments in the presence of vessel noise0 aAcoustically advertising male harbour seals in southeast Alaska 3 a

Aquatically breeding harbour seal (Phoca vitulina) males use underwater vocalizations during the breeding season to establish underwater territories, defend territories against intruder males, and possibly to attract females. Vessel noise overlaps in frequency with these vocalizations and could negatively impact breeding success by limiting communication space. In this study, we investigated whether harbour seals employed anti-masking strategies to maintain communication in the presence of vessel noise in Glacier Bay National Park and Preserve, Alaska. Harbour seals in this location did not sufficiently adjust source levels or acoustic parameters of vocalizations to compensate for acoustic masking. Instead, for every 1 dB increase in ambient noise, signal excess decreased by 0.84 dB, indicating a reduction in communication space when vessels passed. We suggest that harbour seals may already be acoustically advertising at or near a biologically maximal sound level and therefore lack the ability to increase call amplitude to adjust to changes in their acoustic environment. This may have significant implications for this aquatically breeding pinniped, particularly for populations in high noise regions.

10aacoustic communication10aharbour seals10amarine mammals10aNoise10avocalizations1 aMatthews, Leanna, P.1 aFournet, Michelle, E. H.1 aGabriele, Christine1 aKlinck, Holger1 aParks, Susan, E. uhttps://royalsocietypublishing.org/doi/10.1098/rsbl.2019.079502178nas a2200217 4500008004100000022001400041245009300055210006900148260001600217520146300233100001601696700002101712700002401733700002701757700001601784700002601800700002601826700002001852700002601872856006201898 2019 eng d a0824-046900aSeasonal variation in Arctic marine mammal acoustic detection in the northern Bering Sea0 aSeasonal variation in Arctic marine mammal acoustic detection in cDec-12-20203 a

Declines in Arctic sea ice cover are influencing the distribution of protected endemic marine mammals, many of which are important for local Indigenous Peoples, and increasing the presence of potentially disruptive industrial activities. Due to increasing conservation concerns, we conducted the first year‐round acoustic monitoring of waters off Gambell and Savoonga (St. Lawrence Island, Alaska), and in the Bering Strait to quantify vocalizing presence of bowhead whales, belugas, walruses, bearded seals, and ribbon seals. Bottom‐mounted archival acoustic recorders collected data for up to 10 months per deployment between 2012 and 2016. Spectrograms were analyzed for species‐typical vocalizations, and daily detection rates and presence/absence were calculated. Generalized additive models were used to model call presence as a function of time‐of‐year, sea surface temperature, and sea ice concentration. We identified seasonality in call presence for all species, corroborating previous acoustic and distribution studies, and identified finer‐scale spatiotemporal distribution via occurrence of call presence between different monitoring sites. Time‐of‐year was the strongest significant effect on call presence for all species. These data provide important information on Arctic endemic species' spatiotemporal distributions in biologically and culturally important areas within a rapidly changing Arctic region.

1 aChou, Emily1 aAntunes, Ricardo1 aSardelis, Stephanie1 aStafford, Kathleen, M.1 aWest, Leigh1 aSpagnoli, Christopher1 aSouthall, Brandon, L.1 aRobards, Martin1 aRosenbaum, Howard, C. uhttps://onlinelibrary.wiley.com/doi/abs/10.1111/mms.1265801993nas 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

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 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 dB re: 20 μPa [root-mean-square (rms) -fast], 102–116 dB re: 20 μPa (rms-impulse), and 120–131 dB re: 20 μPa (peak) and average standard deviations for all metrics were <2.3 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.

1 aSouthall, Brandon, L.1 aCasey, Caroline1 aHolt, Marla, M.1 aInsley, Stephen, J.1 aReichmuth, Colleen uhttp://asa.scitation.org/doi/10.1121/1.513942201790nas a2200133 4500008004100000245012300041210006900164520129100233100002301524700002301547700001801570700001701588856005101605 2019 eng d00aLong-term evidence of noise-induced permanent threshold shift in a harbor seal ( Phoca vitulina )0 aLongterm evidence of noiseinduced permanent threshold shift in a3 a

In psychophysical studies of noise-induced hearing loss with marine mammals, exposure conditions are often titrated from levels of no effect to those that induce significant but recoverable loss of auditory sensitivity [temporary threshold shift (TTS)]. To examine TTS from mid-frequency noise, a harbor seal was exposed to a 4.1-kHz underwater tone that was incrementally increased in sound pressure level (SPL) and duration. The seal's hearing was evaluated at the exposure frequency and one-half octave higher (5.8 kHz) to identify the noise parameters associated with TTS onset. No reliable TTS was measured with increasing sound exposure level until the second exposure to a 60-s fatiguing tone of 181 dB re 1 μPa SPL (sound exposure level 199 dB re 1 μPa2s), after which an unexpectedly large threshold shift (>47 dB) was observed. While hearing at 4.1 kHz recovered within 48 h, there was a permanent threshold shift of at least 8 dB at 5.8 kHz. This hearing loss was evident for more than ten years. Furthermore, a residual threshold shift of 11 dB was detected one octave above the tonal exposure, at 8.2 kHz. This hearing loss persisted for more than two years prior to full recovery.

1 aReichmuth, Colleen1 aSills, Jillian, M.1 aMulsow, Jason1 aGhoul, Asila uhttp://asa.scitation.org/doi/10.1121/1.512937901896nas a2200169 4500008004100000022001400041245012700055210006900182260001600251300001600267490000800283520131900291100002301610700001901633700002301652856005101675 2018 eng d a0001-496600aThe production and reception of underwater sound in Hawaiian monk seals ( Neomonachus schauinslandi )0 aproduction and reception of underwater sound in Hawaiian monk se cJan-09-2018 a1741 - 17410 v1443 a

The endangered Hawaiian monk seal is a primitive phocid (true) seal endemic to the tropical Hawaiian Islands. At present, there is a lack of substantive bioacoustic information available for this species, with no formal descriptions of underwater vocalizations and limited data concerning underwater hearing. To address these knowledge gaps, we are working to better understand species-typical auditory capabilities and sound production by thoroughly evaluating a single individual living in human care. A mature male monk seal was trained to perform an auditory go/no-go signal detection task in water. Detection thresholds were measured for narrowband tones across the frequency range of hearing to generate a full underwater audiogram. Additionally, an acoustic recorder was placed in this monk seal’s living enclosure for a full year, enabling characterization of his underwater repertoire and seasonal trends in vocal behavior. This study presents the first examination of underwater vocalizations in Hawaiian monk seals, provides insight into the perceptual abilities of this species and the evolution of underwater hearing within the phocid lineage, and enables improved assessments of noise effects on these vulnerable seals. [Work supported by Navy’s Living Marine Resources Program.]

1 aSills, Jillian, M.1 aParnell, Kirby1 aReichmuth, Colleen uhttp://asa.scitation.org/doi/10.1121/1.506772302525nas a2200157 4500008004100000022001300041245008300054210006900137260001600206300001100222490000700233520200800240100002802248700002602276856006502302 1962 eng d a0003347200aThe role of vocalization in the social behaviour of the northern elephant seal0 arole of vocalization in the social behaviour of the northern ele cJan-01-1962 a7 - 140 v103 a

The northern elephant seal breeds on islands off the coast of Mexico and California. It is a highly vocal species and during the breeding season vocalization plays an important role in the maintenance of the species' highly polygynous social organization. The importance of vocalization in this species is demonstrated by the presence in the adult male of a highly modified proboscis which appears to have no function other than the production of vocal threats.

Observation of colour-marked individuals on San Nicolas Island, California, showed that females of a harem tend to remain in a given spot. Females of low dominance are often forced to move by the aggressive behaviour of more dominant females and their pups are likely to become lost and to be bitten by other females. The voice of the pup attracts the mother and stimulates the mother to suckle the pup.

Observations in the field combined with spectrographic analysis of tape recordings reveal two main communicational and structural classes of vocalization, attraction calls and threat sounds. Attraction sounds (mother to pup) are unpulsed, of high and variable pitch, and show clear harmonic structure. Threat sounds (both female and male) have an opposite type of structure; they are highly pulsed, of low and steady pitch, are harsh, and lack clearcut harmonics. In general, pulse interval in the threat sounds tends to increase with body size. Among males, the resonance and volume of the clap-threat increases with the size and development of the proboscis.

Hissing occurs in many tetrapods and probably preceded and facilitated the evolution of vocal cords and patterned sounds; in turn the extensive use of different sounds as a means of communication probably facilitated the evolution of social life in the vertebrates. It is of interest that yearlings use the hiss as a threat and some yearling threat sounds are structurally intermediate between a hiss and the common roaring type of threat.

1 aBartholomew, George, A.1 aCollias, Nicholas, E. uhttp://linkinghub.elsevier.com/retrieve/pii/0003347262901240