The
smallest UK duck, the Teal is common on lakes and large ponds. The population is boosted in winter by migrants from northern Europe. The yellow/buff undertail of the male is often easier to spot than the head pattern. The female, as in most ducks, is mottled brown though the green speculum (patch on the wing) can often be seen.
Rutland Water, Rutland, UK 14th January 2005
Ref:
Teal1
A female. Rutland Water, Rutland, UK 17th February 2006