The typically morose-looking walrus turns out to enjoy playing ball, whenever there happens to be a dead seabird floating about. Walruses have also discovered inventive ways of playing with live birds too.

As anyone who has ever swum underneath a duck to surprise it will know, it can be great fun to play with birds while swimming. Walruses are aware of this and have been spotted doing exactly that, when they are not busy having a carefree game of catch with a handy bird carcass.

While scientists cannot be certain that the walruses are indeed having fun, it is the first time that the animals have been seen engaging in playful behaviour, as walrus researchers Andrey Gilijov and Karina Karenina of St Petersburg State University, and Anatoly Kochnev of the Institute of Biological Problems of the North, Russia, noted in a paper published in the journal Acta Ethologica.

The birds seemed not to enjoy the encounters so much, and occasionally one would die when a walrus got too rough. Andrey Giljov / Acta Ethologica

The researchers observed a total of 71 walruses in the Chukchi Sea between Russia and the US playing with the birds on 74 different occasions in a number of ways. One of the most popular was "surfacing and splash".

Young walruses were the most playful, initiating more than 80% of the games. The arguably more jaded adult walruses seemed less amused with the birds, but adult males were a little more likely to play than adult females. The walruses did not mind a solitary game with a bird, but in eight cases a group got together to play with a bird.

The walruses weren't fussy when it came to which birds they wanted to play with, study author Andrey Gilijov told IBTimes UK.

"Walruses in our observations had no preference for the particular sea bird species to play with. Glaucous gulls, kittiwakes, tufted puffins and cormorants – walruses played with any bird which was present nearby. However, immature birds have been involved much often – possibly because adult birds are more vigilant and cautious."

Animal ethologist Gordon Burghardt from the University of Tennessee told National Geographic that play amongst animals often had a role in courtship, fighting and feeding. "Think of a cat playing with a rubber mouse, or even real dead ones before eating them, [or] dogs retrieving sticks as compared to retrieving prey," he said.

A walrus is pictured in the midst of a game of surface-and-surprise. Andrey Giljov / Acta Ethologica

Walruses make boisterous play companions for birds and the fun is likely to be very one-sided. Another of the walrus's most popular seabird games was "surfacing and hit and attack from below". However, the researchers noted that in very few encounters with live birds did they end up dead.

When the birds were dead to start with, however, the walruses were not averse to playing with their food.

"Encounters with dead birds were followed by further manipulations with bird carcasses, which included both the consumption of bird soft tissue and object play taking the form of drop–catch behaviour," the researchers wrote in the paper.

A walrus is pictured throwing a dead seabird around Andrey Giljov / Acta Ethologica