The hooded merganser (Lophodytes cucullatus) is not a part of the nature of Dorset. This one I photographed was a single male at the RSPB Radipole Lake reserve for well over a year and for a while it has became part of the 'furniture'! My reason for including it is to qualify a message I am always anxious to give to budding nature watchers who are keen to find something rare and exclusive.
I have always been a numbers person so early on in my bird watching 'career' I understood very well when someone said to me "If you are not sure about which species a bird you have seen is then, out of the options, it is statistically likely to the most common one and you need good evidence to be certain that that is not the case." I have always found those wise words and so, having promoted this message frequently in my nature notes, I felt I should add a rider to it - always expect the unexpected!
The origins of this particular hooded merganser are unknown. A native normally of north America it suddenly appeared on the River Wey at Radipole. It arrived as an immature male bird and it is just possible that it made the journey across the Atlantic to arrive here but far more likely is that it was born to parents that are part of a collection somewhere and before it could be pinioned it made its escape and, finding the company of many other ducks and plenty of food in the centre of Weymouth, it decided to stick around for a while.
Escapes from collections have always been a problem and the plethora sika deer in Purbeck is another case in point. It is particularly true in wildfowl where there is a greater tendency to interbreed with other ducks and to create hybrids which can weaken the genetic strain of the natural birds.