Friday, 21 November 2014

Number 9 - Brambling blizzard

Broadfield - without finches on this occasion...

No.9 January 2008 Finch flock at Canons Farm, Surrey

This is not so much a single day, let alone a single moment, more of a rolling event. It all began on January 1st, when I located a large flock of finches at Canons Farm, feeding in a very large field known locally as Broadfield. There were at least 1,000 present, and my initial scan through them with binoculars revealed the odd Brambling in amongst Chaffinches. However, once the scope was put to work it became obvious that at least a quarter of the finches were in fact Brambling - a 750/250 split!

I returned on January 5th. Word of the finch flock had got around, as at least a dozen other birders were also present, unheard of back in these 'early' days at the farm. Throughout the day the finch flock remained faithful to the field, waxing and waning in number, numbers breaking off to forage elsewhere, then returning to swell those that had remained site faithful. At times all took to the air, swirling and twisting over the earth, pitching down only to take flight abruptly. Together we estimated the flock breakdown as Chaffinch (1,650), Brambling (550) and Linnet (200), an overall flock size of 2,400. By 13.00hrs the numbers peaked, but then soon started to dwindle, leaving 700-800 until the light started to fade.

When I visited on January 19th numbers had fallen to 1,400, although Brambling numbers had increased to 800. The following day (20th) Brambling peaked at 1,200, with Chaffinches numbering 800. I spent most of the afternoon transfixed at this seething mass of birds, white-rumps and nasal calls all around me. I knew it was something that I might not see on such a scale again, certainly not locally.  By January 24th the flock was still at a healthy number - 2,000 - although the breakdown had shifted once more, with Chaffinches outnumbering Brambling in a 1,600/400 split. From this point onwards the flock broke up and such counts were not repeated. It was interesting to observe how the flock size had kept relatively stable over the three weeks, yet the composition had not. Taking the peak counts of the three finch species present, a minimum of 3,000 had been recorded, but this was very much a minimum. Was there a turnover of birds, or were the same birds returning each day?

What had attracted them? The farmer had not taken in the flax crop that autumn and it had been flattened by November winds. The flax had then been rolled by machinery, exposing the seed on the soil surface. It was an open avian feast...

This event was not just memorable as pure spectacle, but also a reminder that such things can occur close to home in areas that might not be considered as worthy of spending your birding time. It certainly opened some local eyes to the potential of Canons Farm, something that has been ongoing ever since. We are still awaiting a return to such large finch numbers.

2 comments:

  1. Wonderful seeing such a flock. Reminds me of a time in the Pyrenees a couple of years ago. It was January and we were
    in a mountainous area well wooded with beeches. Then unexpectedly at about 10am wave upon wave of Bramblings
    flooded overhead. It was a continuous wave for about half an hour. They stopped briefly in the beech woods then quickly moved on. They were like a host of locusts. We estimated 50,000 birds but this was probably an underestimate. Apparently there were over a million roosting in the area. These invasions occur infrequently but quite spectacular and breathtaking when they happen. It seemed there were only a few Chaffinches with them.
    Bob

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  2. Bob, you have got me there - 50,000 Bramblings must have been some spectacle - my 1,200 were exciting enough. I have read of these enormous Brambling roosts before in disbelief. The New Naturalist finches book mentioned a million plus being recorded in Switzerland I believe.

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