The Teal is the smallest dabbling duck, at 35 cm in length. From a distance, the drakes in breeding plumage appear grey, with a dark head, a yellowish behind, and a white stripe running along the flanks. Their head and upper neck is chestnut, with a wide and iridescent dark green patch of half-moon- or teardrop-shape that starts immediately before the eye and arcs to the upper hindneck. The speculum is green in both sexes.
In non-breeding (eclipse) plumage, the drake looks more like the hen; it is more uniform in colour, with a dark head and vestigial facial markings. The hen itself is yellowish-brown, somewhat darker on wings and back. It has a dark greyish-brown upper head, hindneck, eyestripe and feather pattern.
In the United Kingdom a small summer population breeds, but far greater numbers of Siberian birds arrive in winter. This dabbling duck is highly gregarious outside of the breeding season and will form large flocks. In flight, the fast, twisting flocks resemble waders. In the breeding season, it is a common inhabitant of sheltered freshwater wetlands with some tall vegetation. The Common Teal usually feeds by dabbling, upending or grazing.
Information and photograph courtesy of en.wikipedia.org (JM Garg)