The birds' bait ball becomes a bite-sized snack for a hungry humpbackHumpback whales have come up with a novel way for getting an easy snack - stealing birds' dinners. A BBC crew filmed seabirds carefully corralling unwieldy shoals of herring into tightly packed "bait balls" from which the fish are easy to pluck. But they discovered that passing whales would wait for the birds to complete their hard graft before devouring the ball of fish in a single gulp. The team said this was the first time they had seen this behaviour. The footage, filmed off the coast of North America, forms part of the BBC wildlife series Nature's Great Events: The Great Feast. Fish banquet The team witnessed the whales' crafty behaviour as they set up to film vast shoals of herring as they gathered to feed on plankton blooms. The whale came in and scooped up the whole thing in pretty much one gulp - mouth open, whoosh, and the whole thing was gone Joe Stevens, producer While the fish feast, diving birds also congregate, eyeing an opportunity for their own fishy banquet. Joe Stevens, a producer on the programme, said: "Murres (a type of guillemot) dive under the shoal and whittle it down into a ball of fish, using the surface of the water to contain it. They dart around it, picking off the fish. "Other seabirds like gulls then come in to get bits of the bait balls." But while the team expected to capture this spectacle on camera, they were unprepared for what came next. Mr Stevens explained: "We had a cameraman in the water - and we started to notice lots of whales. "And we thought: 'What would happen if the whales got interested in these balls of fish?' And then the whales did get interested. Humpbacks migrate from Hawaii to reach the fish feast "One came in and scooped up the whole thing in pretty much one gulp - mouth open, whoosh, and the whole thing was gone." It was a bit of a shock for the underwater cameraman, he added. Mr Stevens said the crew witnessed the humpbacks scoffing the bite-sized bait balls several times. He said: "It was like the whales had noticed what the birds were doing, and let the birds do all the hard work of creating the balls of fish so they could then come in to scoop them up." He added: "You have to take your hat off to them - it is when you see them doing things like that, you realise that they are really very very clever and that they are aware of their environment and what is going on."