Seals (phocids) are generally not thought to produce vocalizations having ultrasonic fundamental frequencies (≥20 kHz), although previous studies could have been biased by sampling limitations. This study characterizes common, yet, previously undescribed, ultrasonic Weddell seal (Leptonychotes weddellii) vocalizations. The vocalizations were identified in more than one year (2017–2018) of broadband acoustic data obtained by a continuously recording underwater observatory in McMurdo Sound, Antarctica. Nine recurrent call types were identified that were composed of single or multiple vocal elements whose fundamental frequencies spanned the ultrasonic range to nearly 50 kHz. Eleven vocal elements had ultrasonic center frequencies (≥20 kHz), including chirps, whistles, and trills, with two elements at >30 kHz. Six elements had fundamental frequencies always >21 kHz. The fundamental frequency of one repetitive U-shaped whistle element reached 44.2 kHz and descending chirps (≥3.6 ms duration) commenced at ≤49.8 kHz. The source amplitude of one fully ultrasonic chirp element (29.5 kHz center frequency) was 137 dB re 1 μPa-m. Harmonics of some vocalizations exceeded 200 kHz. Ultrasonic vocalizations occurred throughout the year with the usage of repetitive ultrasonic chirp-based calls appearing to dominate in winter darkness. The functional significance of these high-frequency vocalizations is unknown.

中文翻译：

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威德尔海豹产生超声波发声

尽管以前的研究可能会因采样限制而产生偏差，但通常认为海豹（声音）不会产生具有超声波基频（≥20 kHz）的发声。这项研究的特点是常见的，但以前没有描述过的超声波韦德海豹（Leptonychotes weddellii））发声。通过连续记录南极麦克默多峡湾的水下天文台获得的宽带声频数据，在超过一年（2017-2018年）中确定了发声。识别出9种重复呼叫类型，这些类型由单个或多个声音元素组成，它们的基本频率跨越超声波范围达到近50 kHz。十一个声带具有超声波中心频率（≥20 kHz），包括chi，口哨声和颤音，两个声带的频率大于30 kHz。六个元件的基频始终> 21 kHz。一个重复的U形口哨元件的基本频率达到44.2 kHz，下降的chi声（持续时间≥3.6ms）始于≤49.8kHz。一种完全超声chi声元件的源振幅（中心频率29.5 kHz）为137 dB re 1μPa-m。一些发声的谐波超过200 kHz。全年都发生超声波发声，在冬季黑暗中使用基于重复的ultrasonic声的呼叫似乎占主导地位。这些高频发声的功能意义未知。