The Lincolnshire Bird Club

Just a couple of hundred metres over the border in Rutland, but I've just been watching a Rough-legged Buzzard at Great Casterton near Stamford which is a bit closer for those of us in the south of Lincolnshire.
Take the Pickworth road out of Great Casterton. Just past the last house on the left a track forks off to the left. I wa parked 200metres up this track having a break from hedge planting when the RlB flew across in front of me dirty white rump and upper tail clearly showing. It landed on a Leylandii and was mobbed by a crow. It then flew back showing a cold grey/brown back and upperwings to land on one of my tree shelters just 50 metres from my truck. I watched it through binoculars for several minutes. From the extensive dark bib and the belly patches being confined to the flanks I would say that it was an adult male.
I'm not sure if the track I was on is a public footpath. It was certainly very muddy. Time was about 2pm
Regards
Hugh Dorrington

Sorry, this has apparently been re-identified as a pale tailed Common Buzzard. It still looked like a Rough-legged to me.
Regards
Hugh

Is it me, or has there been an increase in the number of pale buzzards in Lincolnshire this year. If I go to Cornwall/Wales/Scotland the majority of birds are dark - I estimate that at the moment 1 in 10 Lincolnshire birds (that I have seen this winter) seems to be what I would call 'pale'. This isn't based on any scientific calculation by the way.....

Does anyone have a national figure for the % of pale birds in the UK population?


Common Buzzard - M Watts, Louth Nov 2008 (The light feathers covering this bird legs makes you look twice!)


Common Buzzard - N Clayton North Carlton Jan 2009

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Andrew Chick
Website: http://www.forktail.co.uk/

Hi Andy,i have noticed in recent years an increase in pale morph Common Buzzards,especially in my local area.The second photo reminds me of a bird i had at Worlaby last autumn,pretty stunning in flight with its white scapular patches,and wholly white underparts and head.There is a bird at Worlaby at the moment,which had me take a second look,before i found the juv. Rough-leg,which is quite pale,and has a white v-shaped mark on the rump when seen in flight and when perched at long range can look mis-leading.


Regards



Steve

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http://www.brachytron.blogspot.co.uk

http://www.LincolnshireOdes.blogspot.com

http://www.flickr.com/photos/routy

Interesting question, my gut reaction would be that this is a 'founder effect', ie within the British population when it was at its lowest ebb few white morph birds survived the era of persecution (or alternatively were not ever here in the first place) and thus the genes for pale morph Buzzzards almost disappeared from the population. The sudden resurgence in eastern England might therefore be the result of colonisation by Continental birds, witness the big Common Buzzard movement this autumn...

this from Kruger et al. (2001) Evolution 55 (6):

The common buzzard is highly variable in color, and three main morphs have been distinguished (Glutz von Blotzheim et al. 1971; Melde 1983), although the substantial variation even within these morphs led Ulfstrand (1970, 1977) to describe a continuous spectrum from dark brown to almost pure white (see also Cramp and Simmons 1980). The frequencies of the main morphs vary across Europe. Some authors have suggested that there is clinal variation in morph composition (Ulfstrand 1977), but it is now widely accepted that geographic clines are not detectable (Melde 1983; Del Hoyo et al. 1994). Nevertheless some generalizations can be made.

The dark morph is always the rarest morph, ranging from 0.1% in southern Germany (Dittrich 1985) to over 3% in central Germany (Scherner 1980), 9% in Sweden (Ulfstrand 1977), and up to 17% in another region in central Germany (Zang et al. 1989). The light morph is more common than the dark morph, ranging from 2.3% in southern Germany (Dittrich 1985) to over 10% in central Germany (Scherner 1980), 14% in Sweden (Ulfstrand 1977), and its highest frequency is 21% in central Germany (Zang et al. 1989). Indeed, using the frequencies of the two morphs given above, they are significantly correlated (r 5 0.963, P 5 0.03). The intermediate morph is always the most common, ranging from around 60% (Zang et al. 1989) to 98% (Dittrich 1985). Thus, the typical European situation consists of a polymorphic population with the majority of birds being intermediate.

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Dr Alexander C. Lees
Lecturer in tropical ecology
Manchester Metropolitan University

Lab Associate
Cornell Lab of Ornithology,
Cornell University

http://www.freewebs.com/alexlees/index.htm
@Alexander_Lees