The canvasback feeds almost entirely by diving to consume the leaves, roots and seeds of aquatic plants. It usually dives to depths of around 2 metres when feeding, and remains submerged for 10 to 20 seconds, but will sometimes dive to depths of 9 metres (3). The canvasback will occasionally also feed at the water surface, either grabbing food items from the surface, or upending and submerging the head underwater. This species also eats a variety of insects, crustaceans and small fish (8).
Gregarious for most of the year, except when breeding, the canvasback is often seen foraging in large flocks. At migration stopover sites, extremely large flocks of over 1,000 individuals are often seen (3). Pair bonds are established during the spring northward migration, which commences in early February. Breeding birds arrive at the nesting grounds around early April, with the females often returning to the same site to breed each year (5) (9).
The female canvasback builds the nest, which is a bulky structure built on a mat of floating dead plants or suspended from emergent vegetation (3). Usually, 9 or 10 eggs are laid, and are incubated for around 24 days (2). The male canvasback usually abandons the female during incubation to gather with other males at moulting grounds and begin the southward migration (9).
The chicks, which have brownish upperparts and yellowish underparts, can fly at 63 to 77 days and reach sexual maturity at a year old (2). Most female and juvenile canvasbacks begin the southward migration in early September and arrive on the wintering grounds around late November (9).