Thomas Pemberton
Why the British Isles sit on a migration crossroads
Britain's position on the western edge of Europe makes it a funnel rather than a destination. Birds moving between breeding grounds in Scandinavia, Iceland, Arctic Russia and the Canadian Arctic, and wintering areas in Africa, Iberia and the Mediterranean, have to cross or skirt our islands. Some are passing through at speed; others stop for days or weeks to refuel before pushing on.
Understanding the main routes — the flyways — turns a random walk into something far more deliberate. You begin to know which wind, which coast and which week gives you the best chance. Two things shape everything. Most landbirds are reluctant to cross large expanses of open sea, so they follow coastlines wherever they can. And our weather sits at the meeting point of Atlantic lows and continental highs, which determines whether birds drift to the east coast or the west.
The three flyways worth knowing
Most British migration can be usefully filed under three headings.
- The East Coast route. Birds arriving from Scandinavia, the Baltic and further east make landfall from Shetland and Fair Isle down through Aberdeenshire, Yorkshire and Lincolnshire to Norfolk and Suffolk. Headlands such as Spurn Point, Flamborough Head and the North Norfolk coast are classic first-landing spots, and easterly winds in autumn can produce genuine "falls" of birds that have been pushed off course.
- The West Coast route. This carries birds arriving from Iceland and Greenland, along with many seabirds and waders moving between Arctic breeding grounds and our estuaries. Watch the Hebrides, the Solway, Morecambe Bay, the Dee Estuary and the coasts of the Irish Sea.
- The overland and Irish Sea crossing. Many passerines come up through France and Iberia, crossing the Channel in the south and south-west — Portland Bill, the Isle of Wight, the Pembrokeshire islands and the Welsh and Irish coasts. In autumn, birds bred here funnel back the same way.
Scotland's Northern Isles are effectively the front door for Scandinavian and Arctic arrivals, while the south coast is more of a side entrance for birds moving up from the Mediterranean and Africa.
What turns up, and when
Timing matters as much as location. Roughly, the year runs like this.
- March to early April: the first returning wheatears, sand martins, chiffchaffs and little ringed plovers. Winter wildfowl such as pink-footed geese and whooper swans are heading north.
- Mid-April to mid-May: the peak. Swallows, willow warblers, cuckoos, whitethroats and garden warblers arrive, with the last migrants, including spotted flycatchers and swifts, into mid-May. Reed and sedge warblers fill the wetlands.
- June to July: quiet for passerines, but wader passage begins early. Green sandpipers, wood sandpipers and returning curlew sandpipers appear on muddy edges by the second week of July.
- August to October: the main autumn push. Waders peak on estuaries, then pipits, wagtails and chats move through, followed by thrushes. Easterlies bring drift migrants such as wrynecks, red-backed shrikes and bluethroats to east coast headlands.
- November to January: arrivals of redwings, fieldfares and whooper swans, and in some years an irruption of waxwings from Scandinavia.
Reading the weather like a birder
Wind direction is the single most useful variable. In autumn, a spell of north-easterlies funnelling down the North Sea often produces the best east coast birding, because birds heading south-west from Scandinavia get drifted towards our shores. Add rain or fog and they are forced to put down, which is when headlands and coastal scrub come alive. Equally, a night of clear skies and light southerlies may empty the coast again as birds continue south.
In spring it works in reverse. Persistent southerlies bring overshoots — birds that have flown past their intended latitude — and the first warm pulses after a cold snap can drop a wave of migrants into sheltered valleys and coastal hedgerows.
Tide and time of day matter too. Estuaries concentrate waders on the rising tide, pushing them closer to the shore, while headlands are often best in the first two hours after dawn, when night migrants settle and feed.
Turning observations into a useful journal
A nature journal becomes genuinely predictive once you record the conditions alongside the birds. Aim for consistency over completeness: a short entry made on the same walk each week beats a detailed one made twice a year.
- Date, time, location and a brief note of the exact spot, so you can return to it.
- Weather: wind direction, wind strength, cloud cover, rain and temperature. This is the data that lets you link a species to a set of conditions.
- Species, numbers and behaviour — feeding, singing, arriving, moving through or lingering.
- First and last dates for the year: first swallow, first cuckoo, last wheatear. Over several years these become your own phenology record.
- Anything unexpected, and where it came from if you can guess. A redstart on the east coast in September tells a different story to one on the west coast in April.
Reread your journal before you head out. After a couple of seasons you will notice patterns you would otherwise miss: the way a north-easterly in the second week of October reliably brings thrushes to a particular hedge, or how the first willow warbler always turns up within a few days of a certain tree coming into leaf. That is the real reward of keeping notes — not the record itself, but the anticipation it builds.
