BTO migration blog

Spring and autumn are exciting times for anyone who watches birds. Here on this blog we will make predictions about when to expect migrant arrivals and departures, so that you know when and where to see these well-travelled birds.

Tuesday, 13 September 2011

Autumn storms

The first autumn storms have hit and have had a big effect on migration already. During strong windy conditions, migration for smaller birds comes to a halt as they seek shelter and take the opportunity to rest and, if possible feed-up in preparation to continue their journeys.The day counts of visible migration at Spurn Point illustrate this perfectly. On Sunday 11 September, prior to the winds increasing, 2,280 Swallows were counted heading south over the Point; yesterday with gale-force south-westerly winds only 33 were seen.

Strong westerlies, particularly those associated with fast tracking storms that cross the Atlantic in a day or so often bring North American birds with them, and this weekend’s storm did just that; over thirty Buff-breasted Sandpipers arrived in the UK during the weekend. This high Arctic breeding wader leaves its breeding grounds in Alaska and western Canada during August and September, heading for the Paraguayan and Argentinian pampas. The eastern breeding birds complete this huge migration in one long flight over the sea from New England to Paraguay and Argentina, so are often prone to getting caught up in these fast tracking storms. The winds also brought the first American passerine to our shores, a Red-eyed Vireo, to the Isles of Scilly. This bird would have been making its way to northern South America or Cuba.

Red-eyed Vireo above by Joe Pender

In the UK early autumn storms also bring seabirds closer to land and provide the opportunity for observers to witness some impressive movements of these maritime birds. In the last three days, over ninety Sabine’s Gulls have been seen, from Cornwall to Dumfries and Galloway, and over thirty Grey Phalaropes have been seen from coastal headlands and a few inland reservoirs, including in the London area. Both of these are true oceanic birds.

Sabine’s Gull by Joe Pender

September and October are the most exciting months in a migration watchers calendar. Light winds at anytime during this period, particularly light southerly winds, can produce huge movements of pipits, finches and hirundines – Swallows, House Martins and Sand Martins - during September, and large movement of thrushes, buntings and larks in October. Strong westerlies can bring birds from North America, whilst strong easterlies can result in birds arriving from as far away as eastern Siberia.

So what can we expect over the coming weeks?

As the weather quietens down in the next few days and with winds from the south and east we can expect large movements of finches, pipits and hirundines, as they head off to Africa and we could see the arrival of few Red-backed Shrikes.

You can follow migration as it happens by checking out the BirdTrack maps and reports.

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