Gentoo penguins (Pygoscelis papua) react to underwater sounds

Abstract

Marine mammals and diving birds face several physiological challenges under water, affecting their thermoregulation and locomotion as well as their sensory systems. Therefore, marine mammals have modified ears for improved underwater hearing. Underwater hearing in birds has been studied in a few species, but for the record-holding divers, such as penguins, there are no detailed data. We played underwater noise bursts to gentoo penguins ( Pygoscelis papua ) in a large tank at received sound pressure levels between 100 and 120 dB re 1 µPa RMS. The penguins showed a graded reaction to the noise bursts, ranging from no reactions at 100 dB to strong reactions in more than 60% of the playbacks at 120 dB re 1 µPa. The responses were always directed away from the sound source. The fact that penguins can detect and react to underwater stimuli may indicate that they make use of sound stimuli for orientation and prey detection during dives. Further, it suggests that penguins may be sensitive to anthropogenic noise, like many species of marine mammals.

The common murre (Uria aalge), an auk seabird, reacts to underwater sound

“…2). This signal was identical to the one used during a previous playback study on Gentoo penguins, which reacted strongly to this type of signal (Sørensen et al, 2020). The MFA recording was a recording of a U.S. Navy model 53 C sonar, obtained from the U.S. Navy.…”

Maritime traffic trends around the southern tip of Africa – Did marine noise pollution contribute to the local penguins' collapse?

“…High levels of underwater noise levels can directly affect individual animals by decreasing their foraging success, impacting their sensory abilities (e.g. hearing, orientation) and inducing higher stress levels (see Kight and Swaddle, 2011 Penguins (e.g., Wever et al, 1969), Gentoo Penguins (Pygoscelis papua) have demonstrated a strong directional avoidance reaction to underwater noise at received levels between 110 to 120 dB re 1µPa RMS, while no behavioural response was observed with received levels at 100 dB re 1 µPa RMS (Sørensen et al, 2020). Similar behavioural avoidance responses were noted for the common murre (Uria aalge), with received noise levels varying from 110 to 137 dB re 1 µ Pa RMS (Hansen et al, 2020).…”

Aerial hearing thresholds and ecoacoustics of a threatened pursuit-diving seabird, the marbled murrelet Brachyramphus marmoratus

“…Increasing levels of anthropogenic noise in coastal marine waters are making such data and assessments an increasingly important conservation tool (Elmer et al 2021). Although underwater auditory data was not collected for this study, the detection of underwater sound has so far been documented in 4 species of aquatic or seabirds: common murre , long-tailed duck Clan gula hyemalis (Therrien 2014), gentoo penguin Pygos celis papua (Sørensen et al 2020), and great cormorant Phalacrocorax carbo (Johansen et al 2016, Hansen et al 2017. Of these, empirical underwater auditory thresholds have been measured from only the long-tailed duck (Therrien 2014) and great cormorant (Larsen et al 2020).…”