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, 22 September 2017

From Russia With Love?

When it comes to pace of change in the avian world, it's hard to beat late September in western Europe. Summer visitors are departing en masse, as evidenced by the estimated 100,000 House Martins logged at Sandwich Bay Bird Observatory on 20 September, with large movements of that species and Swallow noted at several other locations. At the same time, wintering birds are starting to pour in, reflected by the rapidly rising BirdTrack reporting rates of waterfowl like Brent Goose and Shoveler.

Historical BirdTrack reporting rate for Brent Goose

The vagaries of the weather at this time of year adds to the rapidly changing picture. Whilst we were discussing American waders and passerines last week, attention is now turning towards potential arrivals from the east, as a large area of high pressure – with associated easterly airflow – is building over Russia. Two Pallas's Grasshopper Warblers, a species that breeds from central Russia eastwards and typically winters in southeast Asia, have already arrived in the UK, one in north Norfolk and one on Fair Isle, and a female Siberian Thrush made it to Shetland. Perhaps rarer still, these days at least, was a Yellow-breasted Bunting found on Out Skerries, Shetland on 20 September. This species is thought to have suffered a 90% population decline, owing mainly to trapping in its non-breeding range, and is now classed as Endangered.

More common species to look out for this week include departing Chiffchaff and passage Wheatear, both of which reach their peak autumn reporting rates on BirdTrack this week. That said, it seems to have been a poor autumn for Wheatears to date, so it will be interesting to see if this picks up in the remainder of September. It's also the best week of the year for Barred Warbler, a lumbering Syvlia warbler that breeds no closer than eastern Germany and southern Scandinavia but is seen regularly in the UK in small numbers each autumn, particularly on the Northern Isles and down the east coast. Waders will remain a feature too, with Dunlin and Snipe both expected to feature on up to 15% of complete lists this week. At the scarcer end of the spectrum, it's the best few weeks of the autumn to find a Dotterel.

Juvenile Dotterel by Nick Moran

Given that the easterly airflow is originating in the Pechora area of Russia, at the northwestern end of the Ural Mountains, it seems reasonable to think that a Pechora Pipit or two might be on the cards for those lucky enough to be birding some of Britain's more northerly outposts. For the rest of us, there'll be lots to enjoy over the next week or so, perhaps including the first big arrival of Redwings. Listen out for their 'tseeep' call over coming nights, particularly on damp, misty evenings when arriving birds will tend to be lower and therefore easier to detect.

Redwing by Nick Stacey
Redwing by Nick Stacey
Nick Moran

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