What walruses want


Figure 1.

On 20 March 2008, a BBC camera crew captured remarkable footage of walruses (Odobenus rosmarus) apparently hunting spectacled eider ducks (Somateria fischeri) overwintering amid the pack ice of the Bering Sea (see http://news.bbc.co.uk/earth/hi/earth_news/newsid_8673000/8673614.stm). What? Walruses hunting ducks? Didn't they eat clams and other shellfish? What nonsense! Indeed, such was the (not very) learned (as it turned out) consensus of my biologist colleagues. Yet here was visual evidence that these white-tusked, bristle-lipped pinnipeds might be something more than the bottom-feeding mollusk-munchers I had thought them to be. My surprise was made only greater upon discovering that the son of a 19th-century whaling ship's captain had been trying to tell me this since 1889. And he'd not been alone.

The authors of a paper describing the above-mentioned sightings (Arctic 2010; 63: 53–56), published in the same month the film finally appeared on the BBC website, were careful to mention that they saw no duck captured as the walruses rushed them from below. Aha! Were they, then, just scaring the birds for fun in some maritime version of “bowling for buzzards” as practiced by The Lion King's Pumbaa? My disbelief came under sustained fire, however, as I read several accounts reporting fowl to occasionally feature on walrus menus. One, published in 2004 (Polar Res 2004; 23: 111–14), recorded thick-billed murres (Uria lomvia) being taken time and again by walruses off Coats Island in Hudson Bay, Canada. All they left behind were the bones and feathers, the walruses' pumping tongues creating enough of a vacuum to strip the birds of their softer body parts. Another report (Polar Res 2010; 29: 455–57) recounted numerous successful attacks on pink-footed geese (Anser brachyrhynchus) off the Norwegian island of Svalbard, the flightless, molting birds as easy a target as turkeys at a fairground shoot. Even bits of a swift black guillemot (Cepphus grylle) had found their way into the gut of a walrus off Alaska's St Lawrence Island (Mar Mammal Sci 1990; 6: 348–50). I wondered who was the more astonished, that guillemot or me.

OK, so walruses have a thing for the odd chicken dinner, but my humiliation burgeoned when I discovered that they also enjoy beefier burgers. Papers recounting seals being taken by walruses had been dribbling in for years behind my back (see for example Polar Biol 1984; 3: 11–18 and especially Meddelelser om Grønland, Bioscience 1977; 46: 44). And if that were not enough, the Sptizbergen Travel website even posted photos of a walrus feeding on a bearded seal (Erignathus barbatus)

Figure 2.

The gruesome truth: a walrus eating a ringed seal (Pusa hispida).

I threw up my hands, however, when I realized that the aforementioned whaling ship's lad had beaten all these reports to publication by nearly a century. Back in January 1889, Robert Walker Gray offered the following in The Zoologist (Third Series, Vol XIIL): A male Walrus which was shot measured 11 ft from the tip of the nose to the extremity of the spine, and 9 ft in girth. The stomach of this Walrus was filled with large pieces of Seal's skin, with the blubber attached, and also of pieces of liver. Last season we shot two, and both their stomachs were similarly filled; one of them, which was shot in the water, had a floe Seal in its mouth which it had just captured; so that the unfortunate floe Seals, persecuted on the ice by the Bears, are preyed upon by the Walrus while in the water. And it seemed he ought to know. Despite being in his early 20s when writing the above, Gray was already a seasoned explorer of the Greenland Sea, having traveled there with his father on several whaling trips. He seemed a trustworthy source too, eventually becoming a respected physician and an authority on whaling history.

But why should walruses settle for seal when they can polish off a polar bear (Ursus maritimus) or nab a narwhal (Monodon monoceros) and leave me even more embarrassed? Amazingly, even these mighty creatures can be feasted upon. The same Meddelelser om Grønland article recounts a personal communication – from one Ole Brønland – of walruses falling upon a shot polar bear, dragging it under water, presumably to eat it. And up popped Gray again in a 1927 article in Nature (119: 923, intriguingly reprinted in the 22 September 1927 edition of the Brisbane newspaper The Queenslander!) with two observations of narwhal-eating walruses, one made by his father: On an earlier voyage [in 1879], before I commenced sailing with him, my father, the late Capt Gray of Peterhead, came across a narwhal recently dead, and a walrus engaged either in killing it or eating it…The body of [the narwhal] was scored with deep wounds, and the stomach of the [walrus] was packed with its blubber.

I surrendered. Apparently, seal-chomping, bird-bashing, narwhal-slurping walruses have long existed out among the icebergs. Whatever will nature come up with next? Fruit-eating crocodiles? What? (J Zoology 2013; 291: 87–99). Oh, come on, you can't be serious!