Rare cooperative feeding observed in leopard seals

Leopard seals (Hydrurga leptonyx) are predators that feed on penguins, fish, squid and crustaceans in Antarctic waters. This predator is known to be solitary, i.e. hunts alone and many times hides the prey to prevent it from being stolen by other leopard seals. However, leopard seals were recently observed feeding together on the same prey in South Georgia.

This behavior was observed in large groups of leopard seals in St Andrews Bay and Right Whale Bay, South Georgia in 2016. Only two seals were feeding on the carcass at the same time, with minimal aggression, while others were in the immediate surrounding area. One of these events was filmed by British and Australian researchers using a drone.

Cooperative feeding is common in more social mammals, such as dolphins and wolves, and allows these species to more effectively hunt and consume large animals. Yet, prey caught with this hunting strategy has to be shared among the hunting ‘team’, limiting the amount of food that each individual gets. In contrast, leopard seals are solitary and territorial and tend to interact aggressively around food.

This recent observation of the cooperative behavior among leopard seals suggests this species may tolerate other seals under certain conditions. Two potential explanations for this behavior may be:

1. More energy is spent hunting and defending prey items from other seals than hunting and sharing prey. This seems to be more likely when the prey is larger, such as seabirds, because leopard seals can swallow an entire fish at once.

2. Cooperative feeding and processing may be a more efficient method to break apart large prey. Leopard seals lack shearing teeth (common among terrestrial carnivores) and their flippers with small claws are not the best tool to hold prey while breaking it. In a cooperative setting, one seal can hold the prey while the other pulls against, breaking it apart more efficiently.

More research is needed to understand if these observations are true cooperation, or just the seals tolerating each other.

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Source:

Robbins JR, Poncet D, Alistair RE, Hocking DP (2019) A rare observation of group prey processing in wild leopard seals (Hydrurga leptonyx). Polar Biol 42:1625–1630. doi: 10.1007/s00300-019-02542-z

Author: Sara Pedro