Long-tailed Tit ssp. caudatus in Germany

SchwanzmeiseA flock of Chickadees and Tits in the middle of the mountains right in the middle of Germany in hazy weather with low-lying clouds combined with drizzle, chilly wind from the west might contain white-headed Long-tailed Tits, which are normally immediately counted as Aegithalos caudatus caudatus.

The Long-tailed Tit (Aegithalos caudatus) exhibits complex global variation with 19 subspecies recognized. The can be divided into three groups: the caudatus group in northern Europe and Asia. The europaeus group in southern and western Europe, north-east China, and Japan. The alpinus group is confined to Mediterranean Europe and south-west Asia.

The subspecies caudatus of the Long-tailed Tit (Aegithalos caudatus)  breeds in Fenno-Scandinavia, Eastern Europe, the largest part of the former Soviet Union, parts of China and Japan, North and South Korea and Mongolia. Since the appearance of the relevant parts of field guides in european languages, this subspecies is located more westernly and southernly than indicated before. Long-tailed Tits are resident or non-migratory bird species with an invasive occurrence in some years, often finding vast numbers in the Baltic countries and in Northwest Europe.

Several subspecies of the Long-tailed Tits occur in the southern and western parts of the area of subspecies caudatus. These subspecies belong to the so-called alpinus / europaeus assemblage. The distribution area of ​​europaeus extends northwestern to Belgium, Denmark, Germany, the Netherlands, Poland and southern Sweden. Long-tailed Tits opf the subspecies europaeus has been identified as a vagrant in UK, Norway, Russia and Ukraine. The subspecies europaeus is like the subspecies caudatus a resident bird, which can also be invasive.

A large part of the caudatus’s characteristics mentioned in the literature can also be found in europaeus, especially in areas with many intermediate birds. One characteristic of caudatus, however, is diagnostic: a pure white and completely blotched head. Differences in biometrics are marginal (only the average slightly larger tail length of caudatus can sometimes be useful). Differences in sounds have not yet been demonstrated. In addition, there are some additional features that are indicative of caudatus, but can also occur with intermediate birds.

It might be, that numbers of the subspecies caudatus are exaggerated. In a study pursued in the Netherlands, 15 well-documented cases (of a total of 56 speciemen) of caudatus were obsolete. Remarkable is the small number of ring catches. Only two cases of a total of 15 individuals were considered acceptable. The wrong idea about the occurrence may be due, among other things, to ignorance of diagnostic features that resulted in confusion with intermediate Long-tailed Tits.

It is possible that there are four groups of Long-tailed Tits, which has to be distinguished:

  1. stripe-headed europaeus (as depicted in the usual field guides)
  2. europaeus -like birds (for example, with a vertebral stripe at the head)
  3. caudatus-like birds (e.g., white-headed individuals with single black feathers on the head)
  4. phenotypic caudatus with a pure white head

Which birds are the “type caudatus”?

Long-tailed Tits of the subspecies caudatus must have the following characteristics:

  • pure white, which means “snow-white” head,
  • sharp delimitation of the black neck to the white head,
  • no chest band (not even to a little extend),
  • white belly with flanks, also white, or only superficially pink,
  • white or at least broad-white-banded tertials.

It is important to note, that not every watched Long-tailed Tit observed has to be assigned to a subspecies. If no assignment to a subspecies is possible, leave it as it is.

In light of the features explained above the Long-tailed Tits from the Criewener Polder, Brandenburg/ Germany previously erroneously identified as Aegithalos caudatus, ssp.: caudatus is probably  more europaeus with a clear caudatus-like appearance. See the white-headed individual with broad-white-banded tertials but with a hint of black feathers on the head.

SchwanzmeiseOn contrast, the image of the Long-tailed Tits above was shot on Happy Island – an island of the Yellow Sea of China – and can be dedicated to the subspecies caudatus, probably japonicus or better sibiricus.

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.  Besides the image of the blog, you can find a nice selection of birds in the gallery or in the “Pictures Shop”. Just give a message, if Bird-Lens could serve you with an image needed before the new pictures are online.

 

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