Every winter the number of immigrant birds builds all along the south coast and especially in Dorset around Christchurch Harbour, Poole Harbour, Radipole/Lodmoor and the Fleet. Amongst the incoming birds are waders, geese and ducks and, surprisingly to me, it seems that the teal (Anas crecca) is not only one of the most numerous but also the most overlooked by the casual observer.
I think some inexperienced bird watchers may dismiss them as mallard because of the green on their head. Although closely related to mallard, teal are easily distinguished as they are much smaller and have a clearly visible yellow triangle to the rear, under the wing. This yellow is visible, especially through binoculars, from a considerable distance and is the essential mark of the teal. I think it is also true to say that they are a more social bird than the mallard and tend to keep together in quite large flocks, often a few hundred, some times a thousand, together.
Generally found on our salt marshes around Phragmytes reed beds but you will also find them on sodden riverside pasture and large ponds. So, next time you see a lot of brown ducks, take a closer look. Can you see that yellow flash?