The river's most brilliant secret

The kingfisher is arguably the most spectacular bird in Britain and, for many of us, the hardest to pin down. Most sightings last less than two seconds: a streak of electric blue and orange travelling low and fast down the middle of the river, gone before you have lifted your binoculars. That is not failure. That is the bird behaving exactly as it should.

The good news for anyone living near a lowland river is that kingfishers are far more common than their reputation suggests. A pair will hold a territory of a kilometre or more of water, so on a quiet stretch you are not hunting for a needle in a haystack. You are learning to read one piece of river properly, and then returning to it.

Choosing your stretch and your hour

The first two hours after dawn are reliably the best. Light is low and angled, the water is often glassy, and the bird has to feed hard after a cold night. Evening can be almost as good, but mornings are quieter and you will meet far fewer people and dogs.

Slow lowland rivers, chalk streams and the gentler stretches of larger rivers all suit kingfishers. The best lengths tend to share the same features:

• Shallow gravel runs and gentle riffles where minnows, sticklebacks and bullheads gather
• Overhanging branches of alder, willow and hawthorn, close to the surface
• Margins of reed, sedge and bur-reed, which shelter small fish
• Steep, sandy or earthy banks where a pair can tunnel out a nest
• Very little disturbance — few walkers, no swimmers, no dogs crashing through the shallows

Water clarity matters more than most people realise. After heavy rain, when the river runs brown, kingfishers struggle to hunt by sight and often move or lie low. Give it a day or two after a spate, and head out when the water has dropped and cleared.

Reading the water for likely perches

A kingfisher hunts from a perch, and it uses the same few perches again and again. Look for anything one to two metres above the water with clear, shallow water beneath it: a low branch dipping towards the surface, an exposed root, a fallen trunk, a stone, a bridge parapet, a mooring post.

These regular perches leave evidence. Look for white splashes of droppings on a favourite branch or stone, often on one side and pointing in a consistent direction. Nearby you may find small, greyish pellets of fish bones and scales, coughed up after a meal. Finding a perch like this is worth more than an hour of random walking.

Also watch for hovering. Kingfishers will sometimes hang above the water, wings whirring, before dropping. The plunge itself is quick, steep and usually followed by a return to the same perch to swallow the fish head-first.

Fieldcraft: how to get close without getting close

Kingfishers are not especially shy of people, but they are extremely sensitive to sudden movement. The trick is to be still and screened rather than distant.

• Walk slowly and stop often. Scan twenty to thirty metres ahead rather than staring at your feet.
• Keep bankside vegetation between you and the water where you can, and stay off the skyline.
• Wear dull greens, browns and greys. Avoid white, black and anything bright.
• Use 8x32 or 8x42 binoculars. You will mostly be watching at twenty to fifty metres.
• If a bird flies, freeze rather than follow it. It will often return to the same perch within a minute or two.
• Keep dogs out of the water on these stretches. One swimming dog can clear a kilometre of river.

What you will actually see and hear

Learn the call first. It is a sharp, thin, high-pitched whistle, often given in flight before the bird comes into view — the cue to look up and look low. The flight itself is fast, direct and usually just above the water, with rapid, whirring wingbeats.

As for the colour: it is not always blue. The brilliance is structural, created by the way light interacts with the feathers, so in flat grey light a kingfisher can look disappointingly dark, almost blackish. In low, direct sunshine with the light behind you, it glows turquoise, cobalt and copper. If you can identify the sex, that is a bonus: females have an orange-red lower mandible, males an all-dark bill. Young birds in late summer and autumn are duller and greener, with dark bills, and they wander widely.

Patience, seasons and leaving no trace

Give a promising stretch half an hour of near-stillness before you move on. That sounds like a long time on a cold morning, but it is the single change that turns occasional glimpses into proper sightings.

Nesting runs from March into July, with two or three broods, and involves a tunnel sometimes a metre deep in a vertical bank. If you find an active nest, keep well back and keep others back too — disturbance at the tunnel can cause failure. Winter is underrated: with less cover and a greater need to feed, birds are often more visible, and a hard frost with clear water can produce a memorable morning.

Take nothing but photographs, leave the banks as you found them, and give the river the quiet it needs. Do that, and the flash will come.