They had already decided they could make movie stars out of a flock of dumb clucks. So asking Academy Award-winning actor-director Mel Gibson to voice Rocky, Chicken Run's cocky claymation rooster, must have been a breeze for co-producers/directors Nick Park and Peter Lord, right? Think again.

"We were scared to approach him," confesses Park, himself a three-time Oscar winner for such cheeky short films as The Wrong Trousers and A Close Shave, both featuring clueless inventor Wallace and his patient dog Gromit. "[Gibson] being such a big star... [we thought], what if he says no? It's going to be so embarrassing. But he was just really into having a laugh, and was familiar with Wallace & Gromit. That made it easy to get him on board; he knew our sense of humor and just played along and was a great sport. It's a credit to him really, the way he can do all these different movies with such credibility. We literally pulled him off The Patriot to do a chicken film!" But what a chicken film: The brave little broilers learn that their cushy gig at the egg farm is about to end, and have to fly the coop before they're turned into chicken pot pies.

And speaking of poultry, what is it that's so funny about chickens? "What isn't?" asks Lord. "They are fundamentally funny animals ? the way they walk, their little heads, their big round fluffy bodies and their little spindly legs. The fact that their eyes are on either side of their heads is not funny, so we had to move their eyes to the front of their heads."

Funny, yes. Easy to animate, no. "Quite early on we realized we had kind of chosen one of the worst creatures you could possibly animate," recalls Park. "Most of the chickens are quite rotund, sort of pear-shaped and balanced on two thin legs. For this kind of animation that posed quite a practical problem. Their weight is towards the top... they fall over easily."

"You know, this is the thing about chickens," concludes Lord. "They are pretty damn stupid and they're cowards. So it was so terrific to put them in a heroic role. Especially in the opening sequence, when they're doing all these escapes, behaving like action heroes but looking like these absurd middle-aged English women. It's just a lovely combination."