Saturday, April 21, 2012

Spring moving on a bit further!

An early session of seawatching before being locked into more formal tasks!
Species numbers were similar to yesterday with the exception of Auk numbers that were closer to 1200 birds moving north in the same time span ( 90 minutes ). In addition to these more routine movements a party of Wigeon , a Whimbrel and a flock of 35 Bar-tailed Godwits  moved north. The latter are regular migrants over the sea to and fro their breeding/wintering quarters but these birds seemed a bit early to be on the move , which is usually later in May.

I'm always intrigued by the movement of birds such as Gannet and Razorbill. I usually presume ( not a good trait in science! ) that the Gannets are returning to their major breeding colony on Ailsa Craig  and that they have been feeding further north. Similarly the auks are likely to be moving, at this time of year, to their more northerly breeding colonies, but all such is conjecture. Increasingly information suggests seabirds are having to move over greater distances in order to utilise productive feeding grounds and I guess, certainly in the middle of the breeding season, more care is needed nowadays than previously in presuming birds are simply involved in local movements. Currently, as numbers increase, suggestions as to where the observed Manx Shearwaters originate are on the back burner!!

Late today I was sent a reference to a recently published paper in the Journal of Ornithology based on a fifteen year study of  3127 prey items taken from 37 peregrine nests in the Basque area of Northern Spain. Part of the paper's title is " Are patagial  wing tags a potential predator attraction for harriers?"  In 2009 4 sets of Hen Harrier remains were found in  eyries along with 2 Montagu's Harrier remains , birds of which had been wing tagged. In 2010 a further eight tagged Montagu's Harriers were found. Further details are not available but the results and research are certainly of immense interest. Personally I would have chosen a slightly different title but the meaning may have been distorted in the translation from Spanish.  The accusation that patagial wing tags  negatively affect their hosts has been raised before and possibly this might start a reassessment of the matter.
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