The Speculum feathers, Latin for mirror, on a wing are an area of iridescence usually on the secondary Flight feathers. The Brazilian teal has a large area of lustrous green, extending onto the Primary-feathers; unlike Mallard ducks it does not have the clear black & white bordering. The Bronze-winged duck is named after its very striking speculum. Most Domesticated ducks are descended from the wild Mallard Anas platyrhynchos. How these birds look is dictated by phases and patterns. The Trout colour, seen in Runners and the Rouen Clair only differs from the wild colour through being light phase. The duck’s plumage resembles a brown trout Salmo trutta. The light phase gene not only affects the body feathers but also the border of the Speculum feathers. On close inspection the secondary coverts have fine white tips, unlike dark phase birds such as a Mallard coloured Rouen (duck) or Call duck, which should have a clear black border above & below the speculum. Trout Runner duck bred by Thomas Moody.