Friday, 11 November 2011

Further Notes on this Years Thrush Migrations.

Today on my way up to Hutton Roof, it was very noticeable that there had been a very large fall of Blackbirds in the night, I had over a score just going up the Lane, and there were many more on the roof itself.

The wind spoint things yet again , it was a Easterley and blowing at 20mph+ gust. The only records are: Chaffinch: 8, Greenfinch: 1, Goldfinch 1W, Wren a couple of them scolding me as usual, Fieldfare could be heard but was not seen. Redwing: 5W. and some Common Gulls (18) were going East. Nice to see thousands of Starlings going East having left their Leighton Moss roost.

A follow up to yesterdays notes on this years "Thrush Visible Migration":-

The dates this year where so early, well at least in the special case of the Fieldfare, and reading more into this, that is probably the answer to the “shortfall” question.

I agree the inception would have started prior to the 14th and fortunately for the Thrushes they found a suitable short window on the 13th and the 14th quickly terminated by blocking fronts on the 15th.

Because of this short window I am sure that it was necessary to take advantage for the “bulk” of the Thrushes to use this in what was probably a more so than usual “high concentrated” effort to get through.

Fieldfare numbers where seen to come through on the 14th more or less from first light, which would indicate that they had probably come through (crossed North Sea) on the 13th. The 15th saw a reduction in birds by 50% compared to the previous day 14th, and the 16th and 17th saw yet a further reduction by 50% compared to the 15th and since those dates there has been very little in the way of incoming thrush passage, other than minimal slight upward surge on both the 6th and 7th of November, this slight surge coincided with a change from East to Northerly winds. The birds recorded on these dates where only a eight on the 6th and a tenth on the 7th of the original counts going back to the 14th October.

Another fine example of “bulk birds” on this same day (14th October 2011), but more so in regards to Redwing, was the experience of Martyn Priestley of (Caldene Fields, Bradford, W. Yorks) on the 14th October 2011, recording no less than 3604 Fieldfare, but a exceptional count of 29,371 Redwing. And his comments for that day read:

“An unprecendented watch! With a movement of thrushes I have not witnessed before in all my time of Vis migging! Pre dawn Redwings could be seen were coming in from the N mainly directly over my head due to the low mist. Then around 08.19 light rain moved in this weather system provided a break in cloud cover to the E of Caldene Fields over the East Bierley and Tong area. This window and the light rain brought literally thousands and thousands of Redwings into view including two 4,000+ counts!! Around 0945 till 10.30hrs Fieldfare pushed through again to the S with a single party of over 1000+”.

Also some further notes from Martyn read: “So I am thinking that they were moving above cloudbase and when my window appear + the rain, bingo!”, and yet another further relevant note: Why did no one else get the flood< which I expected. I can only think that as they cleared my window they gained height again with the onset of cloud etc. Because early in the morning I was getting smallish visible parties but overhead calls of unseen birds and suspected they were some above cloudbase or they started to disperse further S. I tend to favour the first option”.

Now then, this example shows what can happen when rainfall enters the equation. He would have had a good count that day like most of us, I am sure, but would he have ever had such a fabulous count but for the welcome “light rain interference”that morning, I doubt it very much. I am sure the light rain had brought the birds down into view from probable earlier unseen high altitude.

The weather this time has so far been sadly dominated by Easterlies! Whereby for me, I associate good “push days” with light Westerlies, and especially light Northerlies, but after saying that, last year the push date for here was on a very light South Easterley, and again that is probably why even last years count was less than half of the 2009 count!!
Obviously it would be very nice to see more birds, and I am sure that more birds will come if we get more favourable windows and the weather goes worse in the Baltics or the Scandinavias, but for me as I see it the bulk of the birds, have already passed by long ago.