Wednesday, July 28, 2010

Three aspects of bird movements!

I've mentioned before that House Sparrows have a very disjunct distribution in some places on Islay, with thriving populations at various "centres" and notable absences at suitable locations between these. Previously House Sparrows were so common in many places in Britain that they were largely ignored to some extent. Nowadays their numbers are reduced and they enjoy equal status, as far as an interest in the activities and so on, as many other species.

They don't breed around this property but very gradually records appear to be increasing. Yesterday was no exception with two juveniles and an adult male being seen for a brief period. In the normal sense this might have been considered to have been part of some juvenile dispersal activity, but the presence of the adult suggested a more involved movement.

At the moment Willow Warbler movements are in full swing. Doubtless the recent foul weather has not assisted and held things up to some degree. After what appeared to be a quiet period in the late morning, I was surprised to see numbers of warblers, 13in fact, feeding in my "thistle garden", a wave of activity that then passed leaving only a couple of birds behind. I hadn't seen many others earlier when out locally and it seemed a wave of movement was happening down the valley. Migrating birds tend to move overnight, rest and then feed up voraciously before tackling another stage. Does this suggest birds dispersing from local populations very gradually move out from their natal areas until filled with the urge to move on? Despite searching south of the house later nothing could be seen of them.

A colleague advises that a young Eagle Owl he ringed in 2007 has recently been recovered in Scotland. A journey of approximately 190 miles northwards and one that will doubtless set conjecture circulating once again on this species. Whilst a rather different sort of journey, what's the distance between the Low Countries and our East Coast or the even more "convenient" English Channel crossing!!!!

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