Leopard seals resemble their terrestrial namesakes in two ways. They have polka-dot pelts.
And they are powerful, generally solitary carnivores that are quite capable of killing a human being if they so choose—
as has indeed happened once, in 2003, when a British marine biologist was the victim.
Curiously, though, there have also been reports of leopard seals behaving in a friendly manner towards people—
apparently trying to present gifts, in the form of prey, to divers. Until now, there has been no explanation for this philanthropy.
But work just published in Polar Biology by James Robbins of Plymouth University, in Britain,
suggests that what the seals are actually looking for is a dining partner.
Mr Robbins and his team were studying leopard seals in the waters around South Georgia,
an island in the Southern Ocean 1,500km from the tip of the Antarctic peninsula.
Instead of diving, or watching from ships, they used drones to carry out their observations.
These drones recorded hitherto unobserved behaviour on the part of the animals.
First, belying their solitary reputation, the seals came together in groups to attack king penguins
(twice the size of the gentoo penguin in the photograph) that were entering the sea from a rookery on the island.
Second, when a seal did catch a penguin in these circumstances it would sometimes offer to share it with a neighbour
in a way reminiscent of divers' tales of gift giving.
What looked like an aberration might thus be a normal way of behaving. But why?
Mr Robbins's suggestion is that sharing a penguin with a neighbour makes it easier to eat.
A close look at footage the drones recorded shows that seals in such partnerships take it in turns to feed.
One holds the bird tight in its jaws while the other rips off a chunk of flesh and swallows it. Then they swap roles.
By contrast, for a lone seal to reduce a penguin to bite-sized chunks means
whipping the prey around in its jaws with as much force as it can muster, in order to tear lumps of flesh free from the carcass.
This commonly happens, but is thought to be extremely tiring. Better, therefore, to find a buddy and enjoy a meal together.