On World Migratory Bird Day, RSPB England's Lucy Hodson explores the fantastic feats undertaken by migratory species as they traverse the skies to and from their summer and winter grounds.

It starts with a single scream. You see it, high above, a crescent moon silhouette circling. They’re back!

The moment our swifts return to the skies is often heralded as the start of summer. These iconic birds are one of many species that only spend a part of their year in the great British blue. The rest of their time is spent on the wing, and in their wintering grounds in southern Africa.

Bird migration is a true phenomenon of the natural world. Some are winter migrants, travelling from northern countries to spend the colder months in our comparably milder climate. Some only pass through, using the UK as a pitstop on the way to and from their breeding grounds elsewhere.

Others, like swifts, are summer migrants, and the ones that often capture our hearts and imagination. There’s a good number of birds that journey to the UK each year in order to raise their young.

Let’s take a look at some of our most iconic, celebrated migrant birds and the phenomenal journeys they embark on…

Swifts

  Credit: Ben Andrew 

Swifts are champions of the skies and are amazing acrobats, holding the crown title of the fastest level-flying bird in the world. Common swifts (apus apus) have been recorded reaching speeds of nearly 70mph. When they’re around, they make themselves known. They’re very social birds, and will form ‘screaming parties’ – flying around at roof height and making a high-pitched screeching call.

Looking at them, they’re built for a life in the skies; their crescent/boomerang silhouette streamlines them as they soar. When a young swift leaves the nest for the first time, it might not land again for another two or three years, remaining constantly on the wing both day and night. This is reflected in their feet, which are so weak that they struggle to perch; in the past people thought they lacked feet altogether!

Returning each year in late April or early May, swifts only grace our skies for a few months. When they’re on the move, they can cover 500-600 miles a day, and the three winter months are spent 5-6,000 miles away in southern Africa.

Swallows

  Credit: Chris Gomersall 

‘One swallow does not a summer make” – it’s an age-old saying with roots in our natural world. Though it may be true, the first swallows we see are a sure sign that spring and summer is well on the way.

These chattering, graceful birds are normally seen returning in April, a few weeks before the swifts.  They will raise two or three broods of chicks throughout spring and summer, before getting ready to migrate back to Africa in September.

Though perhaps not as fast as the swift at 35mph, they still cover some distance; travelling up to 200 miles a day during migration. Their journey takes them to and from South Africa each year – a distance of around 6,000 miles!

Mega migrants

 Credit: Ben Andrew

So swifts and swallows are perhaps two of the most famous migrants, but what about others? Many birds have a similar annual journey – breeding in the UK and Europe, and wintering on the African continent.

Smaller birds like house and sand martins, blackcaps, whitethroats and most other warblers, redstarts, pied and spotted flycatchers all do this. Less obvious ones like cuckoos, nightjars, hobbies and ospreys make the mammoth journeys too.

Champions of migration; the arctic tern.

 Credit: Louise Greenhorn

There are some birds that take migration to a whole new level. Perhaps the champion of migrations is the arctic tern. This bird holds the title of the longest migration of any bird in the world! It’s so good at travelling, it manages to see two summers a year.

After breeding in the northern hemisphere in areas of the arctic circle, the birds head south for the winter. They’ll travel along coastlines, hunting for fish in shallow waters, all the way down to the southern hemisphere. Here they’ll spend the winter in Antarctica (the southern hemisphere’s summer), before heading back to breed again.

This phenomenal migration means the artic tern tallies up a whopping 44-56,000mile journey each year depending on their route!

Help our migrants!

In two decades we’ve lost more than half of our swifts, and we know many of their nesting sites have been lost. If you’d like to help give swifts a home near you, consider putting up a swift box on your house!

We also want your help in mapping swift hot spots in the UK – so take a look at our Swift Tracker app and let us know where you see them.

Find out more about the phenomenon of migration here: https://www.rspb.org.uk/birds-and-wildlife/natures-home-magazine/birds-and-wildlife-articles/migration/ 

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