Scientists reveal new features of the elusive leopard seal

Although leopard seals are some of Antarctica’s apex predators, their solitary habits and lethal reputation, combined with their habitat’s extreme climate, make them one of the most difficult top predators to study on Earth. However, a research team led by Baylor University has now attempted to shed more light on these fascinating creatures’ activities and behavioral patterns by studying 22 leopard seals off the Western Antarctica Peninsula, a region rapidly warming.

By weighing and measuring each seal and tracking their activities and diving patterns using satellite data and GPS tags, the scientists managed to document the flexible behaviors and traits which may offer leopard seals the necessary resilience to cope to Antarctica’s warming climate and environmental stresses.

“This study greatly increases our understanding of leopard seals’ life history, spatial patterns, and diving behavior,” said study lead author Sarah Kienle, an assistant professor of Biology at Baylor. “We show that these leopard seals have high variability (or, flexibility) in these different traits. Across the animal kingdom, variability is vital for animals adapting and responding to changes in their environment, so we’re excited to see high variability in this Antarctic predator.”

The analyses revealed that adult female leopard seals are 1.5 larger and longer than their male counterparts, an unusual phenomenon among marine mammals. According to the researchers, larger females may be better at defending feeding areas, and stealing prey from smaller seals. Moreover, they consume bigger, energy-rich prey, such as fur seals or penguins, while smaller females and males frequently eat smaller prey, like krill or fish.

Females also spend more time “hauled-out” on ice than males. For instance, two females spent two weeks hauled-out on ice in the middle of the ocean, without getting into the water or eating. The scientists argue that this two-week period is when female seals give birth and nurse their pups. Soon after, they wean their offspring and return to their usual activities.

Another interesting finding is that female and male leopard seals are capable of swimming both short and long distances in coastal, as well as open-ocean habitats. For example, one seal travelled only 46 kilometers from where the research team was located, while another one travelled 1,700 kilometers during the same period.

Finally, leopard seals of both sexes appear to be short, shallow divers, reaching an average of 30 meters deep during three-minute-long dives. However, there are exceptions too, with a male diving to 1,256 meters for 25 minutes.

“It’s interesting to see such variation [in movements and dive behavior] in a relatively small number of animals. To me, this means that leopard seals are highly flexible in their movement patterns, and that’s a really good thing in terms of adapting to changes in your environment,” Professor Kienle said.

In future research, the scientists aim to compare these leopard seals with other population across the Southern Ocean. “I have so many more questions, and I’m excited to continue learning about leopard seals for years to come. There’s so much more to discover about this incredible Antarctic predator,” Kienle concluded.

The study is published in the journal Frontiers in Marine Research.

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By Andrei Ionescu, Earth.com Staff Writer