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 18 May 2012

A far from normal spring

It has been anything but a normal spring. March, with its early spring Mediterranean overshoots, at times felt like May. April, with its heavy rain, snow and hail, resembled November, and so far May has felt very unspring-like.

Swallows and House Martins sheltering from the Rain
in Mevagissey, Cornwall, by David Jackson. May 2012

What effect has this had on our migrant birds?

March 2012 became the third warmest March on record, with temperatures often exceeding those in southern Europe.  As a consequence, early March saw higher than average arrivals, for the time of the year, of Wheatears and Swallows. As the month progressed and the temperatures held, it felt more and more like southern Europe and the arrival of over thirty Hoopoes, a couple of Purple Herons, Baillon’s Crake, Woodchat Shrike and Scops Owl only served to reinforce this.

Just as it seemed like spring migration was about to step up a gear the weather turned. April will be remembered as one of the wettest on record, overturning drought warnings in some counties to flood warnings. It wasn’t only in the UK that this weather pattern dominated, southern Europe suffered too.  On 16 April, the mid-morning temperature at Aiguamolls de L’Emporda, northern Spain, was 5 degrees, forcing migrating Swallows to seek shelter in the hides of the nature reserve.

Swallows at Aiguamolls de L'Emporda by Rod Leslie

Further south, gale force winds whipped up huge sandstorms over the northern Sahara and out into the southern Mediterranean Sea, forcing migrants into the water and providing a bonanza for feeding Lesser Black-backed Gulls. The March rush slowed down as rapidly as it had begun, and many of our migrants began to look like they were going to be late back this year. Whitethroats didn’t start to arrive in earnest until late April/early May, two to three weeks later than the norm.

BirdTrack results show that it was a similar pattern for several other species that normally arrive in mid-April, notably Hobby, Cuckoo, Turtle Dove and warblers including Grasshopper, Reed, Sedge and Garden Warblers. BirdTrack reporting rates for all these species are striking, as are those of both Whitethroat and Lesser Whitethroat.

Hobby by Jill Pakenham

So, here we are, mid-May and the weather is decidedly cool and wet. The winds are in the main coming from the north, and for the most part are quite strong. Even though most of our summer migrants are now represented, there are parts of the country in which many are still to arrive. When conditions allow, there are still some impressive movements of birds at coastal watchpoints, so migration is far from over yet and will almost certainly still have some surprises up its sleeve.

This coming weekend the northerly winds are due to turn more southerly, then south-easterly and eventually easterly. If this is the case, migration watchers on the east coast could be in for a bonanza, and as we are moving into the latter half of May, anything could turn up. I know that I’ll be out in search of a Red-footed Falcon or two.

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