This species is one of the worlds rarest ducks. Once common it was pushed almost to extinction by predation as well as from a loss of habitat. Their diet mainly consists of aquatic or marine invertebrates.
Brown teal are strongly territorial during the breeding season. The nest is a bowl of grass under tussock or fern. The male guards the territory while the female incubates and subsequently raises the brood.
The calls differ between the sexes. The males give soft, high pitched wheezy whistles and popping calls, the females give low quacks and growls.
Captive breeding programs have been mainly successful but attempts at rebuilding wild populations have been less so. Predation by dogs, seals, gulls and harriers still being a real problem for these birds.