The cinnamon teal feeds mainly by dabbling at the surface of shallow water, swimming forward with the head partially submerged as it strains food from the water with its beak. It will also forage by upending and head-dipping, and occasionally feeds on land near water (2) (5) (7). Groups of feeding teal will often swim behind each other, taking advantage of food stirred up by the birds in front (5) (7). The diet is varied and includes seeds, roots, aquatic plants, insects, molluscs, crustaceans and zooplankton (2) (5) (7). A higher proportion of animal matter may be eaten in spring, when the females need more energy for egg production (5) (7).
Although usually seen in pairs or small groups during the breeding season, larger flocks of cinnamon teal sometimes form during winter and on migration, and the species often associates with other waterfowl, such as the blue-winged teal (Anas discors), northern shoveler (Anas clypeata) and gadwall (Anas strepera) (4) (5). The cinnamon teal is described as being a quiet species compared to other dabbling ducks, although the male sometimes gives a nasal, whistling call and the female a high-pitched quacking (3) (4) (5).
The breeding season varies with location, but usually starts around April in the north of the range (2) (5). The nest is a well-concealed depression in the ground, usually located in thick vegetation near water and lined with grass, vegetation and down (2) (5) (7). The female alone builds the nest, incubates the 4 to 16 eggs for between 21 and 25 days and cares for the young (2) (5) (7), although the male will remain with and aggressively guard his mate until about the third week of incubation (5) (7). The ducklings are olive-brown above and greenish-yellow below (2) (4), and are able to fly after about seven weeks (2) (5) (7). The cinnamon teal usually breeds for the first time at a year old, and has been recorded living for over 12 years in the wild (5).