Friday, March 28, 2014

The Radipole Merganser

As I was on the south coast of Dorset for a few days earlier in the week it gave me the opportunity to visit Radipole Lake and have a look at the, now resident, drake Hooded Merganser. If you carry out a search for this bird on the internet you will come across masses of comment and dozens of photographs. The big question of course is, 'Is it a wild bird or a presumed escape?' This has a direct bearing on the next question, 'Can I tick it?'
Hooded Mergansers are native to Canada and north America where there are two populations: the western and the eastern, the latter breeds in southern Canada and northern USA south to the Great Plains. In winter these birds move south to Florida and northern Mexico and if the Radipole bird is a genuine vagrant it would be from this eastern population during its southward migration. Nothing unusual there as we know that Lesser Scaup and Ring-necked Ducks make it across most years. But not in June! It's just too early for autumn migration for most of these birds. And this bird was found in June 2008 in a storm drain on Portland. However, that does not mean it necessarily arrived then. It could have been present for a while. Like most other Hooded Mergansers in Britain this bird was/is considered to be an escape. The BOU did not admit Hooded Merganser onto category A of the British list until June of 2009 based on a record from North Uist in 2000:
Immature or female, Oban Trumisgarry, North Uist, Outer Hebrides
23 October – 1 November 2000
The British Ornithologists’ Union Records Committee (BOURC) has admitted Hooded Merganser Lophodytes cucullatus to Category A of the British List following a review of the occurrence of a female or immature at Oban Trumisgarry, North Uist, Outer Hebrides, from 23 October until 1 November 2000 (sight record, photographed).

Hooded Merganser Lophodytes cucullatus. Radipole Lake March 2014
Since that record there have been four more birds:
2002 - Northumberland - 1st winter at Newbiggin-by-the-Sea - 7th to 25th March
2005 - Kent - adult female at Chilham - 4th to 10th December
2006 - Shetland - adult male at Haroldswick and Burrafirth, Unst - 15th April to 2nd May
2008 - Fife - female at Tayport - 26th October to 15th November 
Bob McGowan, Chairman of BOURC, commented:  “Hooded Merganser has had a particularly troubled route through various categories of the British List, but this only emphasises the complexities in assessing genuine vagrancy in waterfowl, particularly with species which exhibit moderate to high escape potential. For example, the National Waterfowl Census revealed that 206 Hooded Mergansers were hatched in Britain in 2001 so caution was justifiable. Since 2000, documented occurrences in the Azores, the Canaries and Iceland, as well as from Newbiggin in 2002 (British Birds 96: 606) and Shetland in 2006 (British Birds 100: 752), have demonstrated a tendency of increasing natural vagrancy, probably a consequence of the species’ better fortune in North America. Largely as a result of this evidence, BOURC voted unanimously to admit Hooded Merganser to Category A of the British List.”

Hooded Merganser Lophodytes cucullatus. Radipole Lake March 2014
The BBRC rejected this bird as being a true vagrant in the 51st annual report on rare birds in Britain and then on Thursday 23rd June 2009 the following message appeared on the UK400 club website:  'After much deliberation, the drake HOODED MERGANSER at Radipole Lake (Dorset) has now been formally accepted on to Category D1 of the UK400 Club British & Irish List. Rather than departing this spring, the bird has chosen to stay at the reserve and has now moulted into eclipse plumage. Although the circumstances in which it first appeared in a storm drain near Ferrybridge were quite favourable for natural vagrancy, the fact that it has remained for so long and has chosen to accompany the local Mallard population in search of food perhaps indicate that it was of suspect origin.' The bird therefore becomes UNCOUNTABLE on any UK400 Club day, life, county or year lists.' That's pretty clear then!

Hooded Merganser Lophodytes cucullatus. Radipole Lake March 2014

However Nigel Hudson and the Rarities Committee had this to say:
'The simple fact is that the majority of Hooded Mergansers seen in an apparently wild state in Britain and Europe will have escaped from captivity. However, some may be completely innocent of this charge, but deciding which individuals deserve recognition as being the genuine article and which should be damned will never please everyone. Being a relatively short-stayer on a loch in Scotland, the Fife female escaped severe condemnation, but a long-staying drake at Weymouth, Dorset, did itself no favours by outstaying its welcome and appears only in Appendix 3 of this report. That said, birders are free to make up their own minds as to whether the Dorset bird deserved the benefit of the doubt. It certainly would not have been the first wild bird, finding itself lost and alone, to adapt to an opportunistic lifestyle, and it could certainly be argued that arriving as an immature, finding itself a suitable haven, and then simply staying put is far from a hanging offence...'
Apart from the discovery date two other factors condemn this bird to the escapee basement. Firstly it has not been displaying truly wild behaviour. But it has! In spring it has been showing natural migratory tendencies and has moved away from Radipole. It has been seen as far away as Chichester and Poole Harbour - missing for four months - I was told by the warden at the reserve. Secondly it is considered to be too tame. If that's the case then there are an awful lot of escaped Tufted Ducks at Radipole.

Hooded Merganser Lophodytes cucullatus. Radipole Lake March 2014
 The bottom line is that this is a cracking bird to see and if you are in the area it's well worth a visit before it disappears. You decide for yourself if you want to count it as a tick on a list. I know what I'll do...!

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