Fascinating mating behavior of leopard seals revealed

A new study led by Sarah Kienle, a biologist at Baylor University, has analyzed the first paired observations of sexual behavior and vocalizations in wild leopard seals. 

Published in the journal Polar Biology, this research represents a significant advancement in understanding the behavior of one of the planet’s most elusive apex predators. 

Complex courtship rituals of leopard seals

Supported by a grant from the National Science Foundation, Kienle and her team have now completed their third published study on leopard seals, shedding light on the complex courtship rituals of these solitary animals.

Kienle’s team observed a two-hour courtship interaction between a male and female leopard seal in Laguna San Rafael, Chile. They documented a variety of behaviors and vocalizations, which highlighted the intricate nature of leopard seal courtship. 

During this period, the male produced 65 underwater calls, mainly low- and high-double trills directed at the female, who in turn made seven in-air calls, including thump pulses, nose blasts, and growls. 

These observations indicate a sophisticated courtship process involving both in-air and underwater communication.

The female remained primarily on the ice, producing in-air calls, while the male engaged in underwater vocalizations seemingly directed toward her. 

Reproductive biology of leopard seals

The findings offer new insights into the reproductive biology of leopard seals, previously understood mainly through sparse observations and studies of captive animals.

“This study marks a significant step forward in our understanding of leopard seal behavior in the wild,” said Kienle, who leads the Comparative Ecophysiology of Animals Lab (CEAL) at Baylor.

“The detailed observations of courtship behaviors and vocal interactions offer a unique glimpse into the reproductive strategies of these solitary animals,” 

Kienle’s lab focuses on understanding how different animals function within their often-changing environments.

Significance of the study

This groundbreaking research not only enhances our understanding of leopard seal biology but also emphasizes the importance of continued study and conservation efforts for these remarkable marine predators. 

“Leopard seals are important Southern Ocean predators; understanding their reliance on sea ice and the drivers of reproductive success within and between populations is crucial for predicting how this species is – and will – respond to rapidly changing conditions across the southern hemisphere,” explained Kienle.

Leopard seal breeding territory

According to the experts, leopard seals are breeding in South America, particularly in Laguna San Rafael. 

“More broadly, these observations of sexual behavior and leopard seal pups in South America correspond with a recent review of sightings of leopard seal births and pups, which showed most sightings of newborns and pups occurred outside Antarctica,” the researchers noted. 

“These data provide additional evidence that leopard seals can – and are – breeding outside of Antarctic pack ice.”

Future research aims to expand upon these findings by collecting paired in-air and underwater acoustic and video data of known sex individuals to better understand competition, territoriality, and female choice in leopard seal mating behavior.

Resilience to extreme climate disturbances

Kienle and her colleagues published their first study on leopard seals in 2022 in the journal Frontiers in Marine Science. 

The study revealed that leopard seals have flexible movement patterns and dive behaviors, potentially offering the resilience needed to survive extreme climate and environmental disturbances around Antarctica and beyond.

Stress physiology of leopard seals

In 2023, the team published a second study in Frontiers in Marine Science, focusing on the stress physiology of leopard seals. 

Led by Emily S. Sperou, a Baylor Ph.D. student in biology, this research examined how cortisol – an important stress hormone – varies among leopard seals. They discovered that leopard seals have the highest cortisol concentrations of any pinniped, which includes seals, sea lions, and walruses.

Understanding leopard seals 

This series of studies significantly advances our understanding of leopard seal behavior, physiology, and ecology. 

The detailed observations and findings provide a foundation for future research and conservation efforts, highlighting the importance of studying these elusive marine predators in their natural habitats. 

By continuing to investigate the behavior and biology of leopard seals, researchers hope to uncover more about their role in the Southern Ocean ecosystem and how they may adapt to a rapidly changing environment.

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