Little Venice

See this year's cygnets before the last brown goes

Find the swans from the path and look at the young ones beside the adults, keeping your distance.

What colour are the young birds?

Grey-brown all over

Born this year and not yet changed. Brown is a young swan's first set of feathers.

Mostly white, with brown patches

Part way through. The brown goes over the winter, a patch at a time.

Every swan here is white

Then these are adults. A pair that raised no young this year looks exactly like this.

I could not find any swans

Swans move between the pool and the wider canal through the day, so this water can be empty.

A cygnet is full grown by autumn and still brown. The white arrives over its first winter, long after it can fly.

This is a clue rather than a certain identification. A bird in its second year can still carry a little brown on the neck.

A mute swan pair holds the same stretch of water for years and drives off its own young before the next brood. That is why a canal pool can hold one family all autumn and then be down to two birds by spring. The grey feathers are a passport while the young are still tolerated.

Common in London in these weeks, though not recorded at this exact spot.

Count the bands now and find the canal's true level

From the path, look at the brick where it meets the water and work upward.

How many bands of different colour can you count?

One

A dark wet band and nothing above it means the wall has been rebuilt or scrubbed lately.

Two

The lower band is wet all the time and the upper one dries out. The line between them is the water's own height.

Three or more

Each band is a different set of things living there, sorted entirely by how often they get wet.

I could not see the wall above the water

Moored boats and overhanging plants cover long runs of wall, so the line can be hidden for a hundred paces.

A canal is held at a steady height by its locks. That is why the band is a sharp line and not a smear.

This is a clue rather than a certain identification. Rain and a passing boat both wet the brick higher for a while.

A canal has no current worth the name and no tide, so its height changes only when a lock is worked. The bands on the brick are a map of that steadiness. On a tidal river the same wall would carry one wide smear and no line at all.