About Aythya collaris (Donovan, 1809)
Aythya collaris, commonly called the ring-necked duck, is a small to medium-sized diving duck. Its standard measurements are: length 15.3–18.1 inches (39–46 cm); weight 17.3–32.1 ounces (490–910 g); wingspan 24.4–24.8 inches (62–63 cm). Adult males are slightly larger than females, and their color pattern resembles that of the closely related Eurasian tufted duck. Males have a gray bill marked with two white rings, a shiny black angular head, a black back, a white line on the wings, a white breast, and yellow eyes. Adult females have grayish brown angular heads and bodies, with dark brown backs. Their dark bills have a lighter band that is more subtle than the male's; they also have grayish-blue feet, and brown eyes surrounded by white rings. Females produce a trilling call described as "trrr". This species has a cinnamon-colored neck ring that is usually difficult to observe, which is why it is sometimes also called "ringbill".
