BBOWT explains the marvels of migratory birds

All sorts of animals migrate, from hoverflies to whales, but it’s birds that really bring migration to life, writes Logan Walker, from the Berks, Bucks and Oxon Wildlife Trust.

Through them, we can see migration in action, visibly unfolding in the air above us.

Around this time of year, our summer visitors are leaving, heading south in search of a warmer climate.

They’re replaced by winter wanderers, fleeing the harsher weather of northern and eastern Europe.

Migration in action

It is a great time to look for birds on the move.

Migrating birds regularly follow features in the landscape, allowing you to stand and stare in awe as flocks fly above your head.

Coastlines often produce spectacular movements as birds don’t want to fly above the sea, so they funnel along the edge of the land.

But birds can also follow rivers, pass through valleys, or along the borders between different habitats.

The art of watching and recording these movements is known as visible migration, or ‘vismig’.

With the right vantage point and weather conditions, vismig can be enjoyed just about anywhere – including in the heart of towns and cities.

October brings flurries of finches and thrushes arriving from the continent.

Ducks, geese and swans are also on the move.

They migrate in noisy groups, constantly calling to each other to make sure they stay in formation.

These calls are often what give them away.

Listen out for the ‘ink ink’ of pink-footed geese or the trumpeting of whooper swans, drawing attention to the birds flying high overhead in V-shaped flocks.

If you aren’t able to find a vantage point to enjoy migration in action, you can see the results gradually unfolding in the landscape around you.

Lakes and reservoirs such as Hosehill Lake near Theale start to fill with wigeons and
shovelers.

Bramblings begin to appear among the chaffinches in woodlands.

Redwings and fieldfares join the local blackbirds stripping berries from bushes.

Each day could bring something new.

The Nature Discovery Centre in Thatcham is always a great place for wildfowl watching, and the autumn is no exception.

We host regular bird walks around the lake with a chance to look out for fascinating wintering migrants – find out more at the events page on our website.

Wayward wonders

As an extra challenge, some birdwatchers set out to find birds that have no business being anywhere near the British Isles.

They’re known as ‘rares’ or vagrants.

These wanderers are often rated on a scale from ‘scarce’ birds, which can be expected in modest numbers most years, to the much-anticipated ‘megas’ – birds that may have only been recorded here a handful of times.

Vagrants are basically birds that turn up out of their usual range.

Something went awry during their migration, causing them to accidentally find themselves in the UK.

It could be an effect of strong winds blowing them off course, an issue with the bird’s own internal compass – or a combination of both.

In autumn, strong easterly winds often bring unusual visitors from Scandinavia and Siberia. Meanwhile, storms crossing the Atlantic can carry vagrants all the way from North America.

One of the more common autumn vagrants is the yellow-browed warbler. They nest in the taiga forests of Siberia and generally spend the winter in South East Asia.

You don’t need to look at a map to realise that shouldn’t bring them anywhere near the UK!

Yet each autumn, hundreds can be recorded across the British Isles, particularly on the east coast.

There’s always a chance of something spectacularly rare appearing in autumn.

It’s that slim chance that gets many birdwatchers out of bed well before dawn, scouring bushes and hoping for a ‘mega’.

For more information on where to see wildlife near you and how to help nature on your patch, visit the trust’s website: bbowt.org.uk