Killer whale flips seals out of water with its tail

Just when the seals thought it was safe to go back in the water . . . along came Bigga
He's an adult male orca or killer whale, about seven metres from nose to tail, weighing probably more than five tonnes and with a dorsal fin almost as tall as Portsmouth's new striker Peter Crouch.

In captivity an orca needs to down a daily 45kgs, equivalent to a small adult common seal. The appetite of a sea-going wild adult is much bigger.

In Whales of the World (1981), Lyall Watson refers to a report of an adult male found to have parts of 13 porpoises and 14 seals in its stomach - and another seal in its throat.
So when Bigga cruised menacingly into South Nesting Bay about 10 miles north of Lerwick, capital of the Shetland Isles, the fear that gripped the local seal colony was palpable.

"They were very aware of his presence and sensed that they were his target", said Andy Foote, an Aberdeen University postgraduate researcher working on the Scottish Killer Whale Project.

"As Bigga cruised up and down very close, staying out of the sea was their best survival strategy. At one point we saw a female with her flippers protectively around her pup, seemingly trying to make sure it didn't panic and slip into the water."

But three hours of patience finally paid off for the huge predator. The watchers realised this when a cloud of blood appeared suddenly on the sea's surface, then there was turmoil as the remains of the pup Bigga had just seized were flipped into the air by a powerful swipe of his tail.

"Killer whales often play with their food in this way", explained Mr Foote. "We don't really know why they do that - it's one of many mysteries that surround these fascinating animals."

Examples of this behaviour are given in Whales of the World: "We have seen a group in the Galapagos dismember a five metre manta ray by throwing it into the air."

Getting to know individual killer whales is an important part of the project engrossing Mr Foote and his colleague, Dr Volker Deecke, from the Sea Mammals Research Unit at St Andrews' University.

Once an orca is identified via photo, it is given a number and a name. Bigga - named after a whale-shaped island between mainland Shetland and neighbouring Yell - is also known as 014.

Often alone, Bigga sometimes joins the pod of five involved in last year's attack on a group of eider ducks that were flightless due to moulting.

That pod's big adult male has the number 032 and the name Busta - after Busta Voe. Its smallest member, a three-year-old numbered 067, has just been named Ossa, a location in north-west Mainland Shetland after public suggestions were invited.

With a different pod of eight reported this summer, the orca presence in Shetland is considered greater than in former times - and Mr Foote feels this is supported by an aspect of local folklore.

Shetlanders have special names for prominent local creatures - for instance the great skua, a rare seabird, is known as the bonxie, the black guillemot is the tystie and the common seal, the selkie.

"Perhaps significantly, however, there isn't a Shetland name for the killer whale", said Mr Foote. "That could indicate it has only been appearing regularly in Shetland waters in comparatively recent times."

If that is the case, one possibility is that it is linked to the disappearance of sand-eels from Shetland and Orkney waters since the 1980s.

Killer whales don't feed directly on them but their normal diet covers a range of creatures - sea mammals, birds and larger fish - that do. Has there been a change in hunting patterns due to the food chain disruption caused by the sand-eel absence?