The duck weighs on average 0.59 kilograms for males and 0.5 kilograms for females. The body of the duck is described as 'chunky' with a stiff fan shaped tail. In the winter, both sexes have similar appearance. Other characteristics include large gray feet and a concave bill, which is gray in the winter but will change to a blue-gray in the spring for males.
Males also display different colors in the spring, changing to a red-brown chest, rump and flank.
The ruddy duck is generally a vegetarian but will also eat animals. The diet includes pond weeds, stems, and leaves, and larvae of midges. Food is acquired by surface dives. The shape of the body along with the feet located at the extreme rear, make the duck an excellent under water swimmer. Reproduction Reproduction begins with an elaborate display by the male in front of the female.