Most people are pretty familiar with the idea of migration. Animals make epic journeys that can cross countries and even continents. Many of these are seasonal, driven by changes in weather, temperature and the amount of daylight. All sorts of animals migrate, from hoverflies to whales, but it's birds that really bring migration to life. Through them, we can see migration in action, visibly unfolding in the air above us.

Various birds are on the move throughout the year, but spring and autumn bring the biggest changing of the guard. In autumn, 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

Autumn 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! Get in touch with your local birdwatching group, or do a bit of research, and you can probably find a reliable site nearby.

Our top five destinations for winter visitors in Hertfordshire and Middlesex

• Stocker’s Lake – Stocker’s Lake is a key refuge for nationally significant populations of water birds in the Colne Valley, including species like Shoveler and Pochard. Managed in partnership with Affinity Water, this nature reserve provides a vital sanctuary for wintering birds. With abundant food and undisturbed habitats, Stocker’s Lake is a haven for a diverse range of aquatic birds, offering them a peaceful retreat during times of disturbance elsewhere in the valley.

• Amwell Nature Reserve – Like the above, Amwell was once a gravel pit but nowadays it is a haven for wildlife with a great variety of habitats and good connections to other nature reserves and habitats along the River Lea. Great Hardmead Lake plays hosts to many winter visitors and with a great viewpoint it makes for excellent serious bird watching or more casual observation. As well as Gadwall and Shovelers, you might be treated to the rare sight of a Smew. Visit in the evening and one thing you are sure to witness is the spectacle of the many wintering gulls that come to the lake in significant numbers. Not just a visual treat but an auditory one too – listen to the screeches, cries and cawing of Black-headed Gulls and Lesser Black-backed Gulls as they reacquaint after a day of foraging far and wide.

• King’s Meads Nature Reserve – as one of the largest water meadows in Hertfordshire, and crossed by various waterways, King’s Meads is a haven for autumn and winter visiting birds. Little Egrets stand out with their snow-white plumage, flocks of Lapwing and wading birds drop by on migration, feeding up in the pools and ditches for their long journeys ahead. As we head into winter, the reserve sees an influx of wildfowl including, Shoveler, Pochard, Wigeon, Tufted Duck and Gadwall. King’s Meads’ pools and ditches also provide winter feeding for Common Snipe. 

• Tring Reservoirs Nature Reserve – also an SSSI, collectively the four reservoirs which make up Tring Reservoirs - Startop's End, Marsworth, Tringford and Wilstone, owned by Canal and Rivers Trust and managed by HMWT as a nature reserve - are one of the best birdwatching sites in southern England. During the colder months, you can find a large number of wintering wildfowl across all four reservoirs, including Tufted Duck, Pochard, Teal, Gadwall, Wigeon and Shoveler with occasional Goldeneye, Goosander and Smew if it gets very cold.

• Lemsford Springs Nature Reserve – this reserve is pretty unique with its spring-fed watercress bed, which is a hugely valuable habitat for aquatic birds, as it does not freeze – even when the temperatures really drop. Along with that, due to targeted habitat management there’s the plentiful supply of freshwater shrimp in the undisturbed lagoons, which means there’s always an abundant food source whatever the weather. Winter 2022/23 was a bumper year for bird watchers visiting the reserve – with up to three Jack Snipe regularly seen, alongside Common Snipe and up to 14 Green Sandpipers.  The reserve’s hides provide great vantage points to watch all the action, as well as protection from the elements!

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 start to fill with Wigeons and Teals. Bramblings begin to appear amongst the Chaffinches in woodlands. Redwings and Fieldfares join the local Blackbirds stripping berries from bushes. Each day could bring something new.

Wayward wonders

Seeing migration in action is always a thrill, but some birdwatchers have rarer tastes. They 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 the weather, such as strong winds blowing them off course. Or it could be 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 southeast 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. They’ve become so common that some people think they might be establishing a new migration route, spending the winter somewhere in Africa.

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’.

So why not grab your binoculars and head outside to see what migratory birds you can spot this autumn? You never know what rare and exciting species might turn up!