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 19 April 2018

Stop, start migration

This spring has been a very interesting one, so far. For the first few weeks it was definitely running late. Chiffchaff, Blackcap, Sand Martin and other early migrants were 2-3 weeks behind their normal migration pattern. Fast forward to the here and now and it is hard to believe migration is late at all. Those birds that should be arriving right now, including Cuckoo, Nightingale and Hobby, are arriving bang on cue.  In northern Britain some species have arrived early. In the last few days, Fair Isle has had its earliest ever Lesser Whitethroat and Dotterel.

Dotterel by Edmund Fellowes

This all goes to show how weather affects our long-distance migrants and how spring migration is a bit of a lottery; arrive here early and in an early spring the gamble may well pay off, this year it probably hasn’t; arrive here late and you might miss the best breeding territories and the strongest mate, this year you might be OK.

With southerly winds some of our early migrants have caught up and pretty much seem to be back on track, as seen in the BirdTrack Chiffchaff graph below. But what has happened to Wheatears? They are still way behind where they should be for this time of the year; check out its BirdTrack graph. It’s getting to the stage where we might consider something more sinister at play rather than just being delayed. Might there have been a problem in the winter quarters?

Chiffchaff BirdTrack reporting rate

Wheatear BirdTrack reporting rate

The forecast for the next few days is for south and south westerly winds, which will be particularly light over southern and central Europe. This should really open the floodgates for our migrants, both those making their way here and for those leaving. I still have Bramblings in my garden but probably won’t have by the weekend.

Brambling by John Harding

So, if you haven’t already heard a Cuckoo you could well do over the weekend, two of our satellite tagged birds are back, you can find more about them here. Keep an eye out for Hobby, and even an early Swift or two. Amongst these many of our migrants will become more obvious, Reed Warblers, Grasshopper Warblers, Whitethroats and Garden Warblers should all be seen and heard over the next few days. Tern passage will start to build too, with Common, Arctic and Sandwich Terns all on the move.

Black Kite by Jill Pakenham

With lots of birds on the move there is bound to be a few overshoots with them, the most obvious are Hoopoe, Purple Heron, Black Kite and Red-rumped Swallow, but we could also see one or two Sub-alpine Warblers and hopefully Alpine Accentor, one that hangs around for a couple of days allowing lots of birders to catch-up with it.
Paul Stancliffe

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