During the last week of September 2012, huge numbers of Blue Tits (Cyanistes caeruleus) have been observed in Nabben at the peninsula of Falsterbo, the south-western tip of Sweden. 24,000 individuals has been migrating at Nabben which is 10% more than what is seen in a whole year in average. In the Migration Counts run by the Falsterbo Vogelstation you see, that only the years 1996, 2003 and 2008 can compete with the migration numbers of this year.
In his „Handbuch der Vögel Mitteleuropas“, Band 13/I „Passeriformes, Muscicapidae – Paridae“ Urs N. Glutz von Blotzheim mentioned that all migrating behavior is shown by the Blue Tit. Some are resident bird, some (especially the youngs) show dismigration and some are migratory, sometimes even in large numbers which is called an irruption. Urs N. Glutz von Blotzheim also mentioned that there are individual differences. Thus some (caged) Blue Tits of a population showed migratory unrest, some not.
Nevertheless, most people regard Blue Tits as regular guests at feeding tables during a snowy winter. However, the authors of a blog about a “Blue Tit Irruption” (dated from 2012-09-27) say, that at least for Sweden Blue Tit is a partial migrant, e.g. a minor part of the population migrates regularely, though not further than to Denmark or northern Germany. Whereas the Blue Tit-population of Great Britain is said to be mostly resident, the Blue Tits of continental Europe north of the alps are only partially resident and stay in their breeding range.
The author of the blog mentioned above describes how during years with low food resources, a large proportion of the population migrates. Blue Tits are dependent on seeds from trees as a food resource (in southern Sweden especially beech mast crop) in 2012, the beech mast crop is very bad but the Blue Tit population is very large, since the beech mast crop was very good in 2011 and, additionally, it seems like the breeding was successful, at least in southern Sweden.
To cope with the growing demand for top shots of the rarer species of the Palearctic Bird-Lens is keen to enrich the range of pictures of birds you can find in the western palearctic. This image is only a first impression, what you will find in the gallery in the “Pictures Shop” very soon. Just give a message, if Bird-Lens could serve you with an image needed before the new pictures are online.
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