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.



Thursday, 12 September 2019

12th -18th September



The past week has certainly felt a bit more autumnal with a definite chill in the air first thing in the morning and ever-shortening days as we slowly move towards the autumn equinox. Migration for many species slowed with the usual suspects for this time of year either missing or only in low numbers. Wrynecks, for example, were very thin on the ground with only a smattering of birds across the UK, with a distinct bias to the south and east. Commoner migrants such Redstart, Whinchats, Pied Flycatchers, and Spotted Flycatchers, as well as scarce migrants like Red-backed Shrike, and Barred Warbler all, saw a dip in their reporting rates this week as the northerly winds of the weekend gave way to lighter winds of a westerly bias, in effect stalling migration.


BirdTrack reporting rate graph for Whinchat showing a drop in reporting rate most
probably linked with unfavourable migration conditions

The effects of ex-hurricane Dorian weren't really felt as it passed to the north of the UK on the 11th September with a band of rain crossing the country being the only indication it had hit us. Perhaps it will be the early part of this week that species such as Baird's, Semipalmated and Pectoral Sandpiper and American Golden Plover turn up in good numbers and maybe something rarer like Yellow Warbler or Solitary Sandpiper?

The continued westerly airflow in the coming week means it is difficult to predict the intensity of migration and the species involved but the coming week is the peak migration time for species like Gannets, Guillemots and Razorbills which will also be heading south away from their breeding cliffs to winter off north-western Africa and the Mediterranean in the case of Gannet and the North Atlantic and the North Sea for Guillemot and Razorbill. Whilst coastal sites are best for these species any strong onshore winds can result in some, especially young birds, turning up on inland water bodies with Gannets even being seen flying down motorways.
Coming from Iceland and Greenland it is hardly surprising that the first Pink-footed Geese of the winter turned up last week on the northerly and north-westerly airflow, even though they are a week or so ahead of the historical average from BirdTrack data. Small flocks were seen on Fair Isle, the east coast of Scotland and North Norfolk, and with more, if the same weather forecast next week we could see more arriving along with the first Whopper Swans of the autumn. The majority of the world's population of Pink-footed Geese (estimated at around 225,000 birds) winter in the UK, in Scotland and Norfolk.

BirdTrack reporting rate for Pink-footed Goose showing the earlier than normal arrival last week.

These aren't the only wildfowl arriving to winter in the UK, Wigeon and Pintail numbers will start to build in the coming weeks as birds arrive from Northern Europe and Russia to take advantage of the relative warmth of UK winters.
Any strong westerlies at this time of year could also produce Grey Phalarope, this species spends the winter at sea but can be blown close to shore or even inland given the right conditions and can stay for a few days, entertaining the crowds with their mesmerising feeding technique which involves spinning around on the water to pick off insects pulled to the surface.

Species focus

Wheatears for many people signify the start of spring as they are one of the first summer migrants to reach the UK, but autumn can also produce large falls of this much-loved passerine. Wheatears of the race oenanthe bred in the UK but many of the Wheatears seen at this time of year will be of the Greenland race, leucorchoa, which undertake one of the longest transoceanic migrations, from their breeding grounds in Greenland and northeast Canada to their wintering grounds just south of the Sahara. It is believed that many individuals fly non-stop from Greenland to Britain and Ireland and other parts of Europe. These Greenland birds are slightly stockier, longer-legged and longer winged than their European counterparts and tend to stay around for a few days as they fatten up before continuing their southward migration.

Wheatear -Photo by Allan Drewitt


BirdTrack reporting rate for Wheatear showing the autumn peak in mid-September.


Weather for the week ahead.

The week ahead promises to deliver a mixed bag of weather with the wind direction seemingly changing from day-to-day. High-pressure over the southern half of the UK over the weekend and the resultant light winds should help those migrant departing out shores- swallows and martins ought to feature in visible migration counts and warblers, Reed, Sedge ad Willow, along with Whitethroat and Lesser Whitethroat, should be a feature amongst grounded migrants. Both Meadow Pipit and Grey Wagtail also take advantage of these lighter winds and a steady stream of these is often a feature of clear autumn mornings.
With a stronger northerly wind direction forecast for the middle of next week keep an eye on the sea for Great Skuas which can often be seen harrying the southbound Gannets and larger gulls.

Grey Wagtail - Photo John Dunn



Scott Mayson and Paul Stancliffe












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