It has been less than a year since I summarised the Northamptonshire status of Ruddy Shelduck and speculated on the possible origins of birds visiting the county. There is an annual pattern of late summer/early autumn occurrences which ties in nicely with the now well established post-breeding, summer moult migration to The Netherlands. It would appear that birds occur locally as a result of dispersal from The Netherlands after they have completed their full body moult, which leaves them flightless for about four weeks.
There are currently two – a male and female – at the southern end of Pitsford Reservoir, which were first discovered on 24th June – a somewhat earlier arrival date than would normally have been expected.
Ruddy Shelducks, Pitsford Res, 30th June 2014 (Mike Alibone)
The date coincides with the arrival of others in the UK: two in Gloucestershire on 19th and singles in Staffordshire on 25th and Cheshire on 28th, while the build-up in The Netherlands has also begun with two hundred or so at Vreugderijkerwaard, west of Zwolle (remember the Hawk Owl? 🙂 ) on 27 June. A flock of ten had also reached the west coast island of Texel by 25th June where, according to René Pop, they are very unusual; from here it is just a short hop to East Anglia …
The Pitsford birds are in active moult and the drake at least is flightless, having shed all its primaries and secondaries. This, then, begs the question, are we now getting some of the ‘Dutch’ birds before they moult?
The origin of the ‘Dutch’ birds is still not fully resolved but we are now more than half-way to understanding where they come from. In an attempt to discover the source of the summer moulting population a Ruddy Shelduck Work Study Group was set up and, in 2013, it launched an investigation into the origin of the large numbers (eight hundred or so) summering at the Eemmeer as well as those elsewhere in The Netherlands. Forty-eight were trapped and fitted with individually numbered yellow neck-collars and seven were fitted with GPS transmitters.
As a result of this we now know that many – if not all – of these birds are from feral populations in Germany and Switzerland, and it has been established that birds from the German lower Rhine and the Swiss birds are connected to each other. However, there are still a number of individuals with collars which have not been seen after having left the Eemmeer in August 2013. The Dutch are still hoping that these may be from the ‘wild’ population in south-east Europe. It’s nice to dream …
Back to the feral birds. The German and Swiss populations are said to be growing, particularly around Lake Constance, at the tri-point of Switzerland, Germany and Austria, where approximately six hundred and forty were counted in February 2014. There is some concern in the region that they may successfully compete with other hole-nesting species and this has conservation implications. For this reason, along with the fact that this is a European ‘C’ list species and, therefore, potentially worthy of admission to the British list, shouldn’t we be taking Ruddy Shelducks a Tad more seriously?