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, 10 April 2014

Still not exactly flooding in

The spring migration momentum has picked up quite a bit this week with Swallows, Blackcaps and Willow Warblers leading the way. However, birds haven’t exactly been pouring in. With high-pressure extending all the way from Spain to southern Britain, the conditions looked ideal for birds that were being held-up further south to make their move, and of course those that were already well on their way did, resulting in a fresh arrival of Grasshopper Warblers, Redstarts, Pied Flycatchers and the first few Common Sandpipers and Lesser Whitethroats, the numbers were on the relatively low side though considering the weather conditions. It seems that birds might have been held-up much further south by strong north-westerlies in southern Spain/North Africa.

Redstart by John Harding

The conditions did, however, bring in the predicted Black Kite; a bird flew along the North Norfolk coast on 9 April, being seen at several sites on the way. Three Red-rumped Swallows also overshot this week.

Black Kite by Luke Delve

Britain is going to be blessed with high-pressure again next week but the wind is largely going to be from the north/north-west and could be pretty stiff at time. There will be periods of very light northerlies though and, at this time of the year these conditions can result in some of the largest arrivals – it seems that migrating birds are more in control flying into a headwind than with a tailwind. It is going to be a game of two halves though – whilst southern Britain enjoys light winds, warm temperatures and reasonably dry conditions, northern Britain will be experiencing strong westerly winds, relatively cool temperatures and, at times, heavy rain.

Whitethroat by Amy Lewis

So, what might we expect? For south coast visible migration watchers, Saturday looks like the day to be out and about. A weak front is forecast to move south overnight on Friday and could produce murky conditions for a brief period, possibly grounding any migrants that left northern France in much better conditions. This could also be repeated on Sunday into Monday and again Wednesday into Thursday.  In between, when the conditions are a little more settled, we might just see the floodgates finally open and enjoy a variable host of long-distance migrants. Whitethroat could be the most obvious arrival, along with Sedge Warbler and House Martin, and as for scarce migrants, Purple Heron is my prediction.

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