I have a book devoted entirely to Mandarins and Wood Ducks, surely two of the most brilliantly plumaged birds in all the world. Obviously we only have the Wood Duck here, but fortunately it is quite common and not difficult to find. As you know there is a sizeable population of Madarins in the UK now.
I read somewhere that the naturalized Mandarins in Europe are faring better than the original wild ones in east Asia these days............They are very shy in Hokkaido, they are probably much easier to photograph in the UK.
I recall photographing Mandarins on the river Stour - lured with bread....no long lens needed!
Wouldn't work here John..........