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 13 April 2012

Migration hits a wall

Having spent the last week or so on the south coast of Kent, full of anticipation for the wonderful spectacle of visible spring migration that I was going to enjoy, the final result was rather disappointing.

Clear blue skies and very light winds for ten consecutive days meant that any migrants that were arriving were too high to see, and the absence of moderate wind, cloud cover and drizzle (I must have been one of the few parents over the Easter break praying for these conditions, at least for a couple of days) meant there was also very few grounded migrants. On the plus side, those migrants that did arrive were presumably able to continue on their journeys directly to their breeding grounds.

Willow Warbler by Neil Calbrade

So what did happen? Further west along the south coast the weather conditions were much more mixed. Under thick cloud cover and moderate north-westerly wind, Portland Bird Observatory experienced its biggest falls this spring so far. On the last day of March there was a fall of around 3,000 Phylloscs (Willow Warblers and Chiffchaffs), 500 Blackcaps, 75 Wheatears, 12 Redstarts, 6 Ring Ouzels and 4 Pied Flycatchers, along with a steady arrival of small numbers of hirundines (Swallows, House Martins and Sand Martins).

One hundred and fifty miles to the east the picture was very different. On the same day under clear blue skies and no wind, I counted 5 Willow Warblers, 15 Chiffchaffs, 12 Wheatears, two Ring Ouzels and no Redstarts or hirundines.

So, migrants have been arriving, some such as Willow Warbler, Chiffchaff and Blackcap, in large numbers, However, for other species the arrival has been very light. For the time of year many of our summer visitors are worryingly absent. There are very few Swallows and Sand Martins around. Whitethroats and Sedge Warblers are also conspicuous by their absence too. This is probably down to southern Europe experiencing poor weather during the last week. Southern Spain and Portugal have had hailstorms, heavy rain and cool northerly winds. These conditions would be more than enough to bring migration to a halt.

With unsettled weather and a northerly airflow forecast for the next few days, migration will be slow. Birds will still arrive in small numbers and coastal watchpoints could see moderate falls as tired bird make landfall. The winds are due to be lighter on Sunday, so this could be the day to be out and about.

No comments:

Post a Comment

Note: only a member of this blog may post a comment.