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

Thursday, 12 April 2018

Migration still slow


During the last week there has been an arrival of summer migrants, with most of the early arrivals represented. However, numbers still seem to be quite low. Although spring feels late this year the first Sedge Warblers have arrived bang on cue and Ring Ouzel has pretty much caught up.

BirdTrack reporting rate for Ring Ouzel

With that in mind it will be interesting to see how the next week unfolds. There is a good window in the weather on Friday going into Saturday when winds will be easterly turning southerly and light across the Channel and the southern North Sea. This should allow anything held up to move, at least those birds that have made it north of the Pyrenees. It looks like there will be a blocking weather front just north of the mountains that will probably stop any birds moving in to it in their tracks.

Pied Flycatcher by John Harding

So, what might turn up? Pied Flycatchers, Redstarts and more Ring Ouzels should definitely be a feature; in fact it might well be a Ring Ouzel weekend. We should see more Black Redstarts too and possibly one or two more White-spotted Bluethroats.

Cuckoos seem to pretty much on time too but if you haven’t heard one yet you could well do at the weekend. With any luck we should have our first satellite tagged bird back too, the closest is just over three hundred miles south of his Suffolk territory, so he might well make his move on Friday. You can follow him and four other tagged Cuckoos here.

Whitethroat by Amy Lewis

Right now we should be seeing Whitethroats, Willow Warblers, Yellow Wagtails and Tree Pipits either moving through or singing on territory; this could well be the case on Saturday morning. White Wagtail and Little Gull are classic birds for this time of the year in these conditions too.

Wryneck by Jill Pakenham

With easterlies forecast it is worth keeping an eye out for a Wryneck or two, especially if you plan on visiting the east coast, and who knows? We might be treated to a Pallid Swift too.

Friday, 6 April 2018

Migrants about to flood in


Spring migration has been a bit of a trickle so far, however, this is about to change. The forecast for the next few days, and into next week, is one of southerly and at times fairly light winds, the ideal recipe for migrants that have been held-up to finally arrive.

Chiffchaffs and Blackcaps should really be here in force now but as evidenced by the BirdTrack graphs they are running about two weeks late.



These aren’t the only birds running late as most of the early migrants seem to be held-up further south. The graphs for Swallow and Wheatear are just as revealing.


As we write this, birds are at last beginning to arrive, several Chiffchaffs and a single Willow Warbler are now singing on the BTO’s Nunnery Lakes, and the first singing Blackcap of the spring has just burst into song at the headquarters.

The winds on Friday are forecast to be coming from as far south as North Africa, which will almost certainly provide a window for some of our later arriving visitors to get here a little early; there is already a report of a Common Swift from Lancashire and the winds are only just turning south. During the next couple of days birds such as Cuckoo, Turtle Dove and Hobby should all be on the cards. The trickle of Yellow Wagtails, Tree Pipits and Ring Ouzels should also grow, and we should see the first push of Sedge Warblers.

With winds coming from so far south, overshoots will be inevitable, Alpine Swift, Hoopoe, Red-rumped Swallow and Black Kite are the classics but a showy Great Spotted Cuckoo would be much appreciated.

A flavour of migration further south has been given to us a by a friend who is currently working on a survey ship 8 miles off the North African coast around Agadir, Morocco. He has seen flocks of Pintail heading north, a trickle of Sandwich and Common Terns accompanied by Arctic, Long-tailed and Pomarine Skuas. 

Long-tailed Skua chasing Sandwich Tern
 by Andrew Williams

Swallows have also been on the move but the highlights have included Grey Phalaropes, a Hoopoe being mobbed by several gulls that managed to run the gauntlet and carry on north, and a Purple Heron that tried to land on the ship but failed and too continued north.

 Hoopoe off Agadir by Andrew Williams

Evading capture

Paul Stancliffe
Scott Mayson