Think about it. If there is an established national pattern of occurrence of a species, which is reflected in Northants, then something must be going on. And it is … with Ruddy Shelduck.
This species occurs annually in the UK in late summer and early autumn and the origin of the individuals involved has been the subject of much debate over the years – see here, here and here for open discussions from Keith Vinicombe and Andrew Harrop, for example. Escapes and ferals certainly do not account for all the occurrences as there is no feral colony in the UK and you can’t tell me that, every summer, there is a mass escape of juveniles (and adults) from wildfowl collections across the UK!
The birds we see here are believed to be from the moult gathering which occurs annually in the Netherlands and which involves any number of individuals between 500 and 1000. Either they overshoot in late summer or they disperse after moulting, resulting in records later in the autumn. The origin of these birds is unknown and may involve wild birds from southeast Europe but this is pure speculation and until the Dutch bother to ring or radio-tag some of them I guess we’ll never know.
The records in Northants mirror those nationally and Ruddy Shelducks have occurred in the county in 20 out of the last 45 years (1969-2013), including this year with a female currently at Pitsford Reservoir. The pattern of occurrence is consistent with the majority of the records in August and September (with a tail in October and some in November). Although many of the records relate to single birds, there have been small flocks – three together in 1989, 1992, 1999, 2005 and 2009 and four together at Hollowell Reservoir on 22nd August 1979 – adding weight to the belief they are not escapes. Other records in months earlier in the year are a puzzle and could partly be explained by escapees or by misidentification of the similar Cape Shelduck (South Africa), which also escapes from time to time and has occurred in the county on several occasions.
Ruddy Shelduck is on the British List but only in Category B, i.e. it has not been proven to have occurred here in a wild state since 1950. Hopefully its status will change for the better before too long so if you haven’t seen one then there’s still time to catch up with the Pitsford bird. Shouldn’t we be taking occurrences of this species more seriously?