Whistling ducks

As they do, they were all up on the grassy bank, pecking away: a whistle of wigeons. (Spelling error coming up here. No, Mr Blipfoto, they are not 'widgeons,' my bird book says so!). As soon as I get near, they do a Dunkirk style retreat into the water. Occasionally, one of the drakes will whistle, a sort of 'pwoo' sound, which is rather lovely.