This is an adult male teal. The female is a mottled brown colour, without the striking head markings. The teal is Britain’s smallest duck.
Teals can be easily spotted in winter, when they gather in large numbers. Many of them will have migrated from the colder climes of the Baltic and Siberia. They can be found on reservoirs and flooded meadows or gravel pits.
Their collective noun, spring, refers to the way a group of teals may suddenly all take to the air at once. Large flocks of teal weaving through the air is a delightful sight.