Western Palearctic Ruddy Shelducks - British occurrencies
October 16, 2007
Keith Vinicombe has very kindly provided the most recent information regarding Ruddy Shelduck status in NW Europe and further east (although 2007 statistics from Holland and Switzerland are eagerly awaited).
KEV is a prime advisor to the UK400 Club on vagrant wildfowl occurrencies in Britain and his eticulous work has been very much appreciated over the past 30 years. Together, we have carefully vetted all of the records and the UK400 Club treatment is a result of his extensive studies.
Ruddy Shelduck A major influx of at least 59 Ruddy Shelducks into Britain and Ireland occurred in 1892, with others at that time reaching as far west as Greenland. This influx has always been considered to relate to wild birds and the species resides on Category B of the British List (species seen in an apparently wild state only before 1950). The numerous records since then are treated by the BOURC as relating to escapes. While many undoubtedly are, there is a strong pattern of late summer occurrences (mainly July-August) and many, if not most of those records, relate to small flocks, a classic characteristic of an irruptive vagrant.
In 1994, there was a major irruption into north-western Europe, involving as many as 351 birds, including about 262 into Fenno-Scandia. This is thought to have involved birds that moved out of south-east Europe and/or south-western Asia in response to drought. There were about 55 seen in Britain that year, including flocks of up to 12. Despite this, the BOURC refused to admit Ruddy Shelduck into Category A, one of the reasons being the existence of a feral population based on the Askania-Nova steppe reserve in Ukraine, but this site is very close to the species’ natural range. Since then, small flocks of Ruddy Shelducks have continued to occur in late summer, but there have been further important developments.
One is the establishment of another feral population based on Moscow Zoo, which reached 294 in January 2004, and another feral population based on lakes and reservoirs in northern Switzerland, which reached 280 in August 2003. Most significant is the establishment of a moult migration to Eemmer, Utrecht, the Netherlands, which reached 430 in July 2006. There is a widespread belief that these birds come from a large feral population in Germany, but there is a snag to this theory: there is no large feral population in Germany! Contemporaneous counts confirm that they do not come from Switzerland.
The Dutch do not know where these birds come from but the prevailing view is that they are wild. Intriguingly, there has recently been some evidence of a regular passage through northern Italy, thought to involve birds travelling to and from Switzerland and perhaps originating in the Balkans.
Interestingly, it is now known from ringing recoveries that the feral population in Ukraine is mixing with wild birds in southern Russia, the population of which has increased significantly in recent years. This is supported by the fact that only 80-90 pairs nest at Askania-Nova whereas up to 2,000 may be present in winter.
Bearing in mind that (1) there are now over 700 Ruddy Shelducks moulting in western Europe every summer and (2) the barriers between wild and feral birds in the natural range are breaking down, there is no reason why Ruddy Shelduck should not be added to the British List. Even if, for the sake of argument, the birds that reach these shores are feral, then they are clearly countable as Category C vagrants.
See British Birds (1999) 92: 225-255 and an update in Birdwatch (2004) 141: 42-44.
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