Wednesday, August 12, 2009

Dunstable Sewage Treatment Works

This beauty is a Ruddy Shelduck, or a Brahminy Duck if you live in India. Today there were a pair like this at Dunstable Sewage Treatment Works, so I took the opportunity to catch up with them this evening. It's what twitchers call an 'insurance tick'. They're not on the official British List at the moment....but they probably will be before too long, because there is a self-sustaining population in north-western Europe and other areas (see below) where it is believed/hoped these originate from - they are particularly nervous birds which suggests that they are wild, rather than feral. They're beautiful birds, and well worth a visit whether you're a twitcher, enthusiastic birder, or what! They're obviously on some sort of avian package-holiday, and have spent the last few days sight-seeing between Tring Reservoirs (in Herts), DSTW and Luton Hoo.

Photo source:

Update (14/8/09): Lee Evans posted the following fascinating info on our local newsgroup:

At the breakdown of the Soviet Union, many zoos and wildlife parks were left in a state of disrepair and mismanagement and one such species which was popular was the Ruddy Shelduck. This bird benefited from the collapse and in the Ukraine and at a site near Moscow, a non-naturalised population spawned. The Ukraine also had a small natural population of this species and both populations soon merged, so much so that now there are several thousand birds.

Each July, Ruddy Shelducks gather to moult at two main sites in Continental Europe - at Emmeer in The Netherlands and at Klingau Reservoir in northern Switzerland, involving up to 1,060 birds at the former site and 450 at the latter. The direct origin of these birds is unknown but considered most likely to be from the Russian states. Migration before and after July in Northern Italy certainly suggests an arrival from the Balkans.

Now, during this moult period - June-August, Britain receives anything between 15 and 100 of these birds in an average summer, which I believe are overshooting birds from these populations and perhaps nominated 'scouts' seeking out new moulting sites as locations in SE Europe continue to dry up.

It is a well known phenomenon that our Common Shelducks gather to moult at Waddensee.

So, in effect, the European population is a mix of natural and non-natural populations which have consequently merged and we have no way of separating like from like. These birds are acting in a very natural way and as such should be treated fairly and with respect. Obviously I accept that a feral population co-exists in Britain, The Netherlands and Germany but the numbers involved in the moult gatherings, far far exceed these numbers and it is clear that both genuinely wild and non-naturalised birds are involved.
Lee G R Evans
British Birding Association

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