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.

Friday, 27 September 2013

Look to the east this week

This week has seen migration step-up a pace. Swallows have been pouring out of the country. On the south coast they were on the move in what was described as ‘biblical proportions’. 34,000 were counted moving through Christchurch Harbour alone on the 22nd, accompanied by 2-3,000 House Martins. Pink-footed Goose flocks increased throughout the week, the first Redwing flocks began to arrive and finches also started to move, mainly involving Goldfinch and Linnet, albeit in small numbers. Bramblings and Lapland Buntings also began arriving bang on cue.

Lapland Bunting by Dawn Balmer

On the rarity front it really was a case of east meets west, with top drawer birds arriving from both directions. Top billing has to go to the North American Eastern Kingbird on Inishbofin, Galway, shared with the Wilson’s Warbler on Dursey Island, Cork? Whilst from the east the White’s Thrush on Fair Isle, Shetland, and the two Brown Shrikes, in Hampshire and on Orkney were not too far behind.

Almost putting these in the shade, however, was the sheer number of Yellow-Browed Warblers that arrived. On Unst, Shetland, 80 were counted on 26 September alone, and birds made it as far south as Kent. With 40 on Fair Isle, Shetland and double figure counts from other sites too, there could be as many as a thousand in the country, surely one of, if not the, biggest arrival of these fantastic little birds ever.

So what of the weather over the next few days? High pressure is pretty much settled over the continent east of the UK, putting us in a fairly constant easterly airflow, at least for the next three or four days. So, this is where most of the action should come from. It is hard to believe that more Yellow-browed Warblers could arrive but a further arrival is definitely on the cards, and it is inevitable that they will bring something rarer with them. A showy mainland, east coast Lanceolated Warbler would be too much to ask of this supreme skulker but it is one to look out for.

Brent Geese by Andy Mason

Brent Geese should really begin to move this week, along with Wigeon and Red-Throated Diver, particularly for those seawatching from the east coast, and for visible migration watchers, Meadow Pipit could put on quite a show, whilst finch numbers should also build through the week.

Black-billed Cuckoo by Su Gough

With everything pointing to arrivals from the east it would be easy to forget the west, and, although the lows tracking across the Atlantic won’t be quite as deep as those of last week, they could still quite easily bring the odd North American bird with them. Black-billed Cuckoo is long-overdue and would be guaranteed a lot of attention if one did arrive.

Friday, 20 September 2013

East meets west

Westerly airflow and Atlantic storms have dominated the weather this week, as have birds that would be expected during these conditions. Leach’s Petrels have been seen in good numbers off north-western coasts, American waders, such as Buff-breasted Sandpiper, American Golden Plover, Baird’s Sandpiper and Wilson’s Phalarope have all been found, along with the second North American landbird of the autumn so far, a Baltimore Oriole on Shetland. Shetland also hosted the first North American landbird this autumn, a Black-and-white Warbler. The north and west have had the lion’s share of the action, which is not that surprising as the Atlantic storms have arrived to the north of the UK. What is a little more surprising is the arrival of birds from the east.

Yellow-browed Warbler by Joe Graham

Despite the almost continuous westerly airflow at least a dozen Yellow-browed Warblers arrived during the week and a couple of Arctic Warblers and a Little Bunting on the northern isles added to the eastern them. New Red-backed Shrikes and Wrynecks were also found but for rarity hunters, these were overshadowed by the Brown Shrike found in Hampshire on the 20th.

The strong westerlies disrupted migration a little but Meadow Pipits did move when conditions allowed, 5,700 were counted moving through Spurn on 17th. Bang on cue, 2,610 Pink-footed Geese also passed over the same site on the 18th, probably on their way to North Norfolk. Swallows and House Martins moved through in good numbers over the same couple of days.

The weather forecast for the weekend promises much of the same. A low will track across the Atlantic and will be stopped in its tracks just off the west coast of Ireland as it comes up against high pressure that extends from Eastern Europe all the way to Ireland. The perfect recipe for more east meets west birding, only this time the action could be much further south. I wouldn’t place any bets but American Redstart in the South west and a Bimaculated Lark in Norfolk would definitely fit the bill but Red-eyed Vireo and more Yellow-browed Warblers might be more likely.

Wednesday, 11 September 2013

Celebrating migration

A week is a long time in migration, and things are moving on apace. The summery weather of late August and the first few days of September has been replaced by much more autumnal conditions, and the birds being recorded have changed accordingly. In this week's strong northwesterlies – particularly in the North Sea – migrating seabirds have featured prominently. Arctic Skua passage has been impressive and the timing has been remarkably faithful to the long-term average in BirdTrack:

Pale-phase Arctic Skua. Problems identifying this tricky group?
Help is at hand in the BTO Bird ID video - Skuas.
Edmund Fellowes

Sooty Shearwater is a true 'global citizen', breeding in the sub-antarctic then moving into temperate zones of the North Atlantic, with numbers in British and Irish waters peaking at this time of year. Birds seen by sea-watchers here in September and October are thought likely to be non-breeding birds, since large-scale passage of birds returning to their breeding colonies occurs off South America in late August. There just wouldn't be long enough for the birds that are still in the seas around our coasts now to get to the breeding grounds in time.

Sea-watchers hoping for a Sooty Shearwater
at the Spurn Migration Festival, 6–8 September 2013.
Nick Moran

Amazing migrations are worthy of celebration, and that's exactly what the Spurn Migration Festival that took place last weekend was all about. Packed with exciting events, there were lots of ways for visitors to sample the marvels of migration. Guided migrant walks, wader- and sea-watching sessions and ringing demonstrations offered the chance to experience migrants first-hand. A programme of instructive talks and workshops helped to put the birds' journeys – and the importance of Spurn itself to these birds – into context. If the event runs again in future, it comes highly recommended!

It was great to see so many people using the BirdTrack App as they enjoyed and recorded the scattering of scarce migrants that were refuelling at Spurn over the weekend: a Red-backed Shrike, a couple of Common Rosefinch and an elusive Wryneck, among others. There were plenty of waders too, including Curlew Sandpiper, Spotted Redshank and some loose flocks of Snipe, seen arriving over the sea.

A recently-arrived Snipe at Spurn – perhaps a bird that was in one of
the small groups seen coming 'in-off' during the Sea-watching event!
Nick Moran

Ahead of time? This year's autumn arrival of Snipe has been
slightly earlier than the long-term average in BirdTrack.

The Spurn Migration Festival also offered unique opportunities to witness the astounding radar patterns recorded at Spurn during the phenomenal fall of thrushes in late October 2012, and to get a migrant's-eye view of the whole area from the top of the lighthouse. The latter gave an insight – from the perspective of a migratory bird – into the reasons why locations like this are such important stop-over sites. Surrounded by sea and mudflats, the habitat provides an oasis for land birds arriving from across the North Sea or moving south along the east coast, as well as a vital landmark for navigating raptors and other day-flying migrants.

Migrant-magnet: a unique view of Spurn Point from the top of the lighthouse,
highlighting the site's attractiveness to migratory birds.

Heading south: the view greeting diurnal migrants like raptors as they reach
the tip of Spurn Point and prepare to cross the mouth of the Humber estuary.
Nick Moran

Talking of migratory thrushes, the BTO Winter Thrushes Survey will launch for its second winter on Sunday 15 September, in time to catch the earliest-arriving Redwing in the next week or so. Even so-called 'resident' species like Blackbird will be on the move, as illustrated by the reporting patterns in both Garden BirdWatch and BirdTrack.

Last week's predictions came to fruition as the bad weather grounded a few more migrants, including a handful of Red-backed Shrike, along the east coast, and the westerly airflow did indeed produce a North American land bird in the form of a stunning – if fleeting – Black-and-white Warbler on Shetland! With north and northwesterly winds forecast to continue until the weekend, it's time to turn our attention to birds arriving from Iceland. Pink-footed Goose numbers should increase rapidly, and we can expect arrivals of other waterfowl like Wigeon and Pintail. Also coming from the same area are many of our wintering Merlin and Snow Bunting, sightings of which should begin increasing too. The first few Lapland Bunting have arrived in the north and west (perhaps an indication that they are from the Canadian / Greenland population) and more should be on their way soon.

Moving up the rarity stakes, the first North American Catharus thrush of the autumn – maybe a Swainson's Thrush – could be on the cards, and how about a hirundine or swift from across the Pond? There's already been a Purple Martin in Holland and a Chimney Swift in Portugal in the last week, so here's hoping!

Friday, 6 September 2013

Autumn migration hits its peak - for some species

The peak period for autumn migration, as measured by large movements of a particular species at a bird observatory, or migration watchpoint, is often thought to run from mid September to mid October. However, for some species the peak has already passed, the last of the satellite tagged BTO Cuckoos left the UK on 26 July.  For others, it is right now, as is the case for Whinchat, and it will be a few weeks away until Meadow Pipits peak. So there is plenty to look forward to.

Meadow Pipit by

Of course, migration is influenced by the vagaries of the weather and birds can either be held up, or leave early, depending on the conditions.  BirdTrack is a good indicator as to what is happening as the autumn unfolds. The BirdTrack reporting rate for Whinchat illustrates this perfectly, and shows that unless things change Whinchat migration is bang on cue.

Whinchat reporting rate graph.

So, how might the weather influence migration this weekend?

Met Office pressure map - - 0100 Saturday 7 Sept

Low pressure is centred over the UK from Friday afternoon into Saturday morning and as a consequence of this the weather is going to be unsettled for most of us. On the face of it it doesn’t look like there will be much movement from the east, however, depending on the timing of rain on the west coast of Norway, migrants here might be tempted to leave and be drifted across the North Sea in a short window of easterly airflow. So with poor weather on the east coast, particularly from Shetland down to Yorkshire, we might see a fall of migrants that should include Whinchats, and possibly a few Red-backed Shrikes. And, who knows? Maybe something altogether more exciting, I’m hoping for a Norfolk Pallas’s Grasshopper Warbler  but will be just as happy with a small fall of Spotted Flycatchers.

Saturday morning looks best for the east coast, whilst on Sunday, interest could turn to the west and perhaps an early North American land bird.