First Observations of Mating Behavior and Sounds in Wild Leopard Seals

Jenn Hoskins
8th July, 2024

First Observations of Mating Behavior and Sounds in Wild Leopard Seals

The loud underwater courtship calls of the primary male leopard seal (Hydrurga leptonyx) likely attracted other individuals to the scene, including a first unidentified seal (a) and a second one observed later (b).

Image adapted from: Kienle et al. / CC BY (Source)

Key Findings

  • The study observed the first documented courtship behavior of wild leopard seals in Laguna San Rafael, Chile
  • Female leopard seals primarily stayed on ice, while males were mostly underwater, using distinct vocalizations to communicate
  • The male's underwater calls and the female's in-air calls are crucial for their mating process, indicating a complex communication system
The reproductive biology of the leopard seal (Hydrurga leptonyx), a top predator in the Southern Ocean, remains largely enigmatic. Recent research conducted by Baylor University provides new insights into the sexual behavior of these elusive marine mammals[1]. This study observed a courtship interaction between a female and male leopard seal in Laguna San Rafael, Chile, marking the first description of such behavior in the wild and offering the first evidence that leopard seals mate in South America. During a 2-hour observation period, the researchers noted distinct behavioral patterns between the female and male seals. The female spent most of her time hauled out on ice, either lying still (69%) or moving (19%). In contrast, the male was predominantly underwater (87%) or at the water’s surface (11%). The female produced seven in-air calls, including thump pulse, noseblast, blast, and growl sounds. Meanwhile, the male emitted 65 underwater calls, such as low- and high-double trills, and other unidentified trills, seemingly directed toward the female. The vocal behavior observed in this study aligns with previous findings on leopard seal communication. Earlier research has shown that leopard seals produce stereotyped calls as part of their underwater vocal displays, with different call types exhibiting varying amplitudes and frequencies[2]. These vocalizations likely play a crucial role in courtship and mating, as they can convey information about the caller's size and stamina[3]. The current study builds on this understanding by illustrating how these calls are utilized during actual mating interactions. Interestingly, the underwater calls continued for an additional eight hours after the primary male had vocalized for an hour and briefly encountered one or two unidentified leopard seals. This extended vocal activity suggests a complex communication system that may involve multiple individuals and prolonged interactions. The following day, the primary male was observed hauled out on ice with a swollen genital opening and a laceration near the preputial opening, indicating an attempted mating and a possible altercation, either with the female or another seal. This study's findings are significant as they reveal a combination of behavioral and acoustic strategies employed by both sexes during courtship. The female's in-air calls and the male's underwater vocalizations appear to be integral components of the mating process. This duality in communication methods highlights the adaptability of leopard seals to their environment, utilizing both aerial and aquatic mediums to maximize reproductive success. The rhythmic and repeated nature of the male's underwater calls, as noted in the study, is consistent with the patterning observed in other marine mammals, such as Weddell seals. Weddell seals produce multiple element calls with distinct timing patterns that enhance the probability of detection, especially over long distances or in noisy environments[4]. The leopard seal's use of repetitive sequences may similarly serve to advertise the male's presence and fitness to potential mates, reinforcing the idea that such vocalizations are honest signals of stamina and endurance[3]. In conclusion, this groundbreaking study by Baylor University sheds light on the previously unknown sexual behavior of leopard seals in the wild. By documenting the intricate interplay of behavioral and acoustic cues during courtship, it provides a deeper understanding of the reproductive strategies of these fascinating marine predators. This research not only fills a critical gap in the knowledge of leopard seal biology but also underscores the importance of vocal communication in their mating rituals, echoing findings from related studies on marine mammal acoustics and behavior.

WildlifeAnimal ScienceMarine Biology

References

Main Study

1) First paired observations of sexual behavior and calls in wild leopard seals

Published 7th July, 2024

https://doi.org/10.1007/s00300-024-03275-4

Related Studies

2) Source levels of the underwater calls of a male leopard seal.

https://doi.org/10.1121/1.4895685

3) Calling underwater is a costly signal: size-related differences in the call rates of Antarctic leopard seals.

https://doi.org/10.1093/cz/zox028

4) Repetition patterns in Weddell seal (Leptonychotes weddellii) underwater multiple element calls.

Journal: The Journal of the Acoustical Society of America, Issue: Vol 116, Issue 2, Aug 2004


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