Mallard (Anas platyrhynchos subsp. platyrhynchos) Species sexually dimorphic, male. Hagerman National Wildlife Refuge, Grayson County, Texas, USA. The refuge is on the Big Mineral Arm of Lake Texoma which is formed by the damming of the Red River. An intermixing of Blackland Prairie and Cross Timbers and Prairies Vegetational Areas. Margin of a lake marsh at ca. 189 m (619 ft) elevation.