Straight away, the fluffy plumage of this bird would tell you that we are dealing with a youngster, here. But it is a confidently swimming youngster, judging from the photograph. Some of our water birds have free-swimming fluffy chicks just about from hatching. These include ducklings, grebes and the ‘gallinules’ (Moorhen and Coot). The bill shape looks wrong for a fluffy duckling and our grebes have striped chicks with stubbier bills than this bird. Baby divers also have robust, chunky bills. So perhaps it is a baby gallinule. But both baby Moorhens and baby Coots have red tones (and blue in Moorhens), balder heads and shorter bills. This jet black baby, with a fluffy head and long ivory bill, is a baby Water Rail.
Black and fluffy No stripes Fully feathered head, no ‘bald patch’ Longish ivory bill
Black, fluffy plumage Obviously a natural swimmer Pale, narrow bill