The Grey Teal - Anas gracilis - is a medium size (41 to 48 centimetres for males and 37 to 44 centimetres for females), mainly brown bird. Male and female are similar in appearance. Top of the head and back of the neck are dark coloured (black to brown), speckled with lighter brown.
Feathers on the back are dark brown with paler edges; rump and tail are dark brown. Feathers on the breast, sides and underside are paler then feathers on the back with the same paler brown edging. Bill, legs and feet are black to slate-grey.
The iris is red-orange, especially in direct sunlight and the white throat is more readily seen in sunlight.
The Grey Teal is similar in colouring to female Chestnut Teal but the latter is darker in colouring and lack the white throat which characterises the Grey Teal of both sexes.
Immature birds are coloured similarly to adults but are paler, particularly on the head and neck. Immature birds have brown eyes. Young birds take nearly a year to achieve adult plumage. Adults moult twice a year; once before breeding and again immediately after breeding.
The Grey Teal is very widespread and highly nomadic found all over Australia living in fresh, brackish or salt water. Most of the population wander over the entire continent depending on the occurrence of rain and distribution of floods. The species is found in greatest numbers in the tree-lined billabongs of the Murray-Darling system.
Grey Teals feed on plant and animal material; plants are sedges, grasses and seeds, animals are beetles and other water insects or their larvae as well as mussels and small crustaceans, especially when feeding in coastal tidal swamps. The feed by upending to reach submerged plants, or by stripping seeds from plants in the water or overhanging the water. When water levels are steady the birds remain in billabongs and lagoons feeding around the edges; if water levels rise and spread out as floods the Grey Teals follow the water and feed on invertebrates flooded out of burrows as well as on the range of seeds and grasses now flooded. This dietary flexibility enables the Grey Teal to feed in just about any body of water.
Breeding begins at any time of the year, triggered by an increase in water level. Nests are built anywhere; on the ground, in crevices in rocks. Tree holes are commonly used inland, these are often more than a metre deep and steep. Sometimes eggs are laid on bare ground and covered with grey down plucked from the female's breast. The extent of the breeding season varies widely depending on the weather; in droughts there is little or no breeding, if flooding is prolonged then breeding continues for months with couples rearing brood after brood.
Four to 14 eggs are laid, usually seven or eight; cream in colour, becoming stained; oval, 54 by 39 millimetres. Incubated 24 to 26 days by the female.
The Grey Teal lives a cycle of boom-and bust with expansion in numbers during floods; once the dry period begins birds disperse or die. Most juveniles survive for only one year and few live longer than 20 months.