Getting your eye in: shape before colour

Most people start a coastal walk trying to name birds by colour, and most come away defeated. The wind is in your face, the light is behind the birds, and everything on the water looks like a duck. The trick is to read silhouette and movement first — birders call it "jizz", that instant impression of size, posture and flight style — and only then reach for colour. A gull flapping with slow, elastic wingbeats is doing something quite different from a cormorant powering along on straight, snappy beats.

Learn half a dozen shapes and you can identify most of what you meet on a British shore before you lift your binoculars. Plan around the tide: two hours either side of low water gives you exposed mud, rock and strandline, and therefore birds. Carry 8x42 binoculars if you have them, and walk with the sun behind you where the path allows.

Telling the common gulls apart

Gulls are where most people give up, which is a shame, because the four you are likely to see are straightforward once you know the shortlist.

• Herring gull — the classic seaside gull. Pink legs, pale grey back, heavy yellow bill with a red spot near the tip, and a loud laughing yelp. Confident, noisy, will take a chip from your hand.
• Lesser black-backed gull — yellow legs and a darker slate-grey back. Slimmer and neater than a herring gull. Common inland in winter, on rooftops and playing fields.
• Great black-backed gull — the heavyweight, with a near-black back and pink legs. It is the bird standing over a dead fish on the tideline, daring anything else to come closer.
• Black-headed gull — small and dainty. Despite the name, the head is chocolate-brown in summer and in winter it is white with a dark smudge behind the eye.

Leg colour is your quickest check, and it holds in poor light. A fifth bird, the kittiwake, is a proper cliff specialist and gets its own mention below.

Cormorant or shag?

Both are long-necked, dark, fish-eating divers that sit low in the water and stand on rocks with their wings held out to dry — the posture that makes people call them "prehistoric".

The cormorant is the bigger, heavier bird, with a thick neck and a bronze-green sheen. In spring it shows a white patch on the thigh and a white face. It often fishes estuaries and even inland lakes, flies with steady, purposeful wingbeats, and tends to leap forward before diving with a splash.

The shag is smaller and slimmer, with a thinner, snakier neck and a more rounded head. In early spring it grows a shaggy crest, which gives it a permanently windswept look. It is a bird of rocky coasts and clear water, diving more quietly and swimming underwater more often than it flies. If the bird is on a sea cliff in summer and looks neat and green, think shag.

Oystercatchers and the wader crowd

The oystercatcher is the one shorebird nobody misidentifies. Black above, white below, with a long straight orange-red bill and pink legs, it is noisy and conspicuous, piping a piercing kleep-kleep as it flies. Watch one working a mussel bed: it either hammers the shell open or slips the bill in and prises the valves apart, and individual birds specialise in one technique or the other.

Other waders reward a little patience:

• Curlew — big, brown, with a long downcurved bill and a haunting cur-lee call.
• Redshank — bright red legs, grey-brown back, forever telling you off with a tew-tew-tew.
• Turnstone — small and speckled, flicking seaweed and pebbles over on the strandline.
• Sanderling — pale, runs along the surf edge like a clockwork toy, never quite getting its feet wet.

Cliff nesters: the summer crowd

On a cliff-top walk between April and July you are looking at a city. A few species carry the skyline:

• Gannet — a big, brilliant white bird with black wingtips and a wash of yellow on the head. Flies on stiff, straight wings, then folds and plunges into the sea from height.
• Fulmar — looks like a stocky gull but flies on rigid wings with occasional wobbles, skimming the cliff face. It has a tube on top of the bill, which is the clue.
• Guillemot — chocolate-brown and white, standing upright on narrow ledges in dense rows. Whirring flight, straight and fast.
• Razorbill — similar, but blacker and chunkier, with a blunt, thick bill crossed by a thin white line.
• Kittiwake — a small, gentle gull with a yellow bill, black legs and black wingtips, endlessly calling its own name from the ledge.

Watching without causing harm

Seabirds and their nests are protected by law in the UK, and disturbance is an offence. In practice, that means a few simple habits.

• Stay on the path and respect rope lines, signs and temporary diversions on cliff tops.
• Keep back from ledge colonies. A bird that leaves the nest to see you off has exposed eggs or chicks to gulls and the weather.
• Keep dogs on leads on cliff tops and along high-tide strandlines from April to August.
• Give roosting waders at least fifty metres, and never walk through a roost for a photograph. They are resting to survive the cold, and every flush costs them energy they cannot easily replace.
• Use binoculars or a scope rather than your feet. If a bird starts alarm-calling or diving at you, you are already too close — back away.
• Leave any chick on the beach alone. The parents are usually close by and watching you.

Pick one unfamiliar bird each walk and learn it properly: where it was, what the tide was doing, what it sounded like. Six trips later you will know your coast in a way that no field guide can give you.