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.

Monday 5 August 2013

There and back again

Two months have snuck by since our last update. It's been anything but quiet for migrant birds during that period though. June will be remembered by some as the Month of the Rare Swift, with long-distance (and very lost) travellers in the form of a Pacific Swift and a Needle-tailed Swift reaching our shores. Rare seabirds soon got in on the action when an exquisite Bridled Tern appeared on the Farne Islands in early July, quickly followed by an even more astounding sight: an Ascension Frigatebird found resting on a harbour wall on Islay on 5 July!

Lots has been happening amongst our more familiar species too. All our satellite-tagged Cuckoos have departed, with several already south of the Sahara! Some juvenile Cuckoos will still be in the country but the vast majority of these are also expected to leave in the next couple of weeks. (Common) Swift numbers are starting to drop off too, though as of last week they were still being recorded on about 30% of BirdTrack complete lists.

Arctic-breeding waders, restricted as they are to a short breeding season, are already heading south again. Wood Sandpiper, Little Stint and Spotted Redshank are amongst the many wader species that can be encountered at this time of year, and certainly spice up late summer birding trips.

Spotted Redshank by Chris Mills
Some Spotted Redshank retain their breeding finery into early August.
Chris Mills

In some years, July sees an influx of Common Crossbill, presumably involving a high proportion of Scandinavian-bred birds. This July certainly lived up to its (cross)billing, as the BirdTrack reporting rate below shows. Furthermore, it wasn't just the more familiar Common Crossbill that arrived but also unusually large numbers of their much rarer cousin, Two-barred Crossbill. This species breeds in Scandinavia and eastwards, lending weight to the suggestion of a Scandinavian origin to these influxes. The geographic spread of the Two-barred Crossbill arrival was noteworthy: whilst influxes are often confined to or at least concentrated on the Shetland and Orkney islands, this year's arrival featured multiple records down the English east coast, from Spurn to East Anglia. 4 birds even had the good grace to spend a few days less than 15 minutes' drive from the Nunnery, providing a nice lunchtime distraction for many BTO staff members!

BirdTrack reporting rate: Common Crossbill
The Common Crossbill influx as reflected in the BirdTrack reporting rate.

A round-up of migration activity in early August wouldn't be complete without a mention of the seabirds passing through British and Irish waters at this time of year. Whilst southern Ireland has had the lions share of goodies (including up to 3 individual Fea's Petrel in one day, plus an even rarer Bulwer's Petrel), counts of several thousand Manx Shearwater have already been recorded from southwest Cornwall on several dates. Whilst this species breeds on offshore islands in Britain and Ireland, some of the other species already logged by seawatchers in the southwest have come from much further afield. At the end of July I was lucky enough to see a scarce Great Shearwater whilst on a 'pelagic' (a boat trip in search of pelagic seabirds). This species breeds no nearer than the island of Tristan da Cunha in the South Atlantic, one of only a very few species to migrate north to winter in the North Atlantic.

Great Shearwater by Martin Elliott, Mermaid II pelagic
'My' Great Shearwater, a few miles south of Land's End.
Martin Elliott

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