They are primarily herbivorous, and mostly graze on pasture grasses and clover, but have been observed eating a wide range of invertebrates.

They are seasonally hunted as a game bird throughout New Zealand, and today the IUCN Red List classifies them as a species of least concern.

The paradise shelduck was formally described in 1789 by the German naturalist Johann Friedrich Gmelin in his revised and expanded edition of Carl Linnaeus's Systema Naturae.

[2] Gmelin based his description on the "Variegated goose" from New Zealand that had been described in 1785 by the English ornithologist John Latham in his A General Synopsis of Birds.

[3][4] The naturalist Joseph Banks had provided Latham with a water-colour drawing of the duck by Georg Forster who had accompanied James Cook on his second voyage to the Pacific Ocean.

[12][13][14] The adult male has a blue-black head and neck, with a black rump and tail; the back and flank are lightly flecked with a pale yellow colour.

The male also has a dark grey flecked with pale-yellow breast and abdomen, chestnut undertail and underwing, and black iris, bill, legs, and feet.

The female, unlike the male, has an entirely white head and neck with a dark grey back heavily flecked with pale yellow.

[12] The rest is very similar to the male with the female's body being dark or light chestnut depending on age and stage of molting.

The females assume their white head during the first molt and 1–2 months after fledging their breast and abdomen turn dark chestnut.

[17] They are common around the hilly farmland characterised by fertile riversides, farm dams, and natural pools of the North Island.

The pair will run away from the young in a crouched position, raising and lowering its half-opened wings to distract the predator.

[12] The paradise shelduck can nest in a variety of places including inside hollow logs, under fallen logs, in-ground holes or trees up to 20 m (66 ft) high, rabbit burrows, under haystacks, piles of fence posts, tussocks, in rock crevices, under buildings, among tree roots, or in culverts.

Early departures from moulting sites begin in March and April, when adults will return to their distinct breeding territories.

[18] The adults are primarily herbivorous preferring pasture grasses and clover while the young eat mostly aquatic insects for the first five weeks of life before grazing on land.

[12] The only group of parasites that affects the Paradise shelduck are the helminths which consist of flukes (Trematodes), tapeworms (Cestodes), and roundworms (Nematodes), with only the flatworms not living symbiotically with the host.

[18] In relation to diseases, recent research discovered the presence of the bacterium Chlamydia psittaci on Paradise shelducks.