13
Jan
13

Dipping into ratial clines

The photograph below is of a ‘Black bellied Dipper’ that has been frequenting the river Little Ouse and the River Thet in Thetford within the south of the county of Norfolk. It’s been there on and off since early November and will probably spend the rest of the winter there.

Although I think they are fantastic birds I don’t overly enjoy photographing Dippers. They are almost always in dark environments under riverside trees and they are piebald, both of which make exposure difficult. With this latest bird add to that the grey skies and dim days of a British winter and you have a challenge on your hands.

I took several photographs when we went to see the bird last week. The one below is not the best, in fact it is distinctly aesthetically unpleasing. I mean, who wants a picture of a dipper sat on a broken wheel trim? However, it shows the bib and chest/belly juncture quite well which is what I wanted you to see. The reasons for this will become apparent later.

Dippers, or to give them one of their proper name of White throated Dipper or European Dipper (Cinclus cinclus) are rare in Eastern England. They are the birds of the west and the north of the UK. However it is an intriguing species with several sub species supposedly separated on appearance. The following has been composed from the bible of birds; Birds of the Western Palearctic (BWP)

Cinclus cinclus cinclus is the nominate form otherwise known as Black bellied Dipper. It inhabits much of the continent.

Cinclus cinclus gularis inhabits England, Wales, Orkneys, east and central Scotland.

Cinclus cinclus aquaticus inhabits central and southern Europe.

Cinclus cinclus hibernicus inhabits Ireland, the Outer Hebrides and the west coast of Scotland.

Cinclus cinclus minor inhabits North West Africa.

Cinclus cinclus caucauscus can be found in much of Turkey and Iran.

Cinclus cinclus persicus also inhabits some of Iran.

Cinclus cinclus uralensis can be found in the Ural Mountains.

There are also several more eastern races from other parts of Turkey and Iran as well as Afghanistan, central China and Eastern Siberia.

The mainland British race gularis has a broad chestnut band on the belly whereas cinclus has a black belly with much reduced chestnut. It is traditionally assumed any of the Black bellied form occurring within England is due to southward movement of Scandinavian birds of cinclus. In the rest of Eurasia the geographical variation is highly complex some populations varying even within the same mountain range.

It is worth noting that uralensis has been known to undertake movements of at least 1000km aquaticus up to 160km and there are two possible British Records of this race. hibernicus which also has a similar appearance to cinclus in that its belly has restricted chestnut and is also known to undertake altitude movement during winter.

The more you read in BWP regarding racial variation the less it becomes clear where the lines can be drawn. I understand birds are even difficult to specifically identify to race in the hand yet alone in the field.

Let’s face it the Thetford bird is probably a cinclus but other options shouldn’t be totally excluded. What a great subject for someone to do a study with satellite tagging. Whatever race the bird is it was wonderful to watch it feeding on Cadis Fly larva; swimming under water to fetch them back to its perch where it nipped off the end of the covering, held on to the larva and shook off the sheath, swallowing the larva whole.

Dipper

Of the following three photos one was taken in Lancashire, one in central Scotland and one in Austria which is the aquaticus race. Can you tell which one it is?

Dipper 1

Dipper 2

Dipper 3

 

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2 Responses to “Dipping into ratial clines”


  1. January 13, 2013 at 9:27 pm

    The first of the three picture is the aquaticus. It looks like the race occuring in Switzerland.

    • January 13, 2013 at 10:15 pm

      Thanks for your interest Thomas. In fact it’s the centre photo taken in the Austrian snow last December that is aquaticus. The top one was taken in central Yorkshire the stronghold of gularis – As the post implies I am not so sure the races can be easily seperated on appearance alone. – if I didn’t know for sure I would have chosen the same as you.


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