Tadorna variegata (Gmelin, 1789)
The Paradise Shelduck is the only shelduck native to New Zealand. Cited
by Darwin in the Descent of Man as an acknowledged counter-example to
the pattern that the male is usually the modified sex of a species
through the mechanism of sexual selection, this species is unique in
that the juvenile birds' plumage is more similar to that of the male
than to that of the female (Darwin 1871). A
flamboyantly colored duck, the female is also brightly colored in
comparison to the male. Females have a bright white head and
chestnut-red body as opposed to the males' black head feathering and
charcoal grey body. Their delicious meat and bright coloring make them
popular targets for hunters on the islands, and they are currently
managed successfully as a game species. They are also a highly vocal
species with the females and males having distinct honks (New Zealand
Dept. of Conservation).
These usually
sedentary and territorial birds flock together between December and
February for the annual molt.
These birds
have a pasture diet of grass, clover and crops (like grain). They will
also eat available aquatic vegetation. Because of increasing
agricultural practices on both North and South Islands, these birds
have expanded their range within the islands since man's arrival and
deforestation for agriculture has occurred. Farmers, however, consider
them a pest species and hunters a prime target species. Despite these
obstacles (and because of them [?]), the
species has been very successful since the imposition of bag limits (New
Zealand Dept. of Conservation).
Their average lifespan is 2.3 years,
though the age range is considerably more diverse (New Zealand Dept. of Conservation).
These birds only breed in the pastures,
grasslands and wetlands of New Zealand. Pairs mate for life, and birds
first breed in their second or third years of life. Pairs usually return
to the same nesting area each breeding season. Nests are built close to
the ground, usually under fallen trees or in dirt holes. Some also
build nests in made-man barns or tree holes. Clutches contain up to 10
eggs and are laid between August and September in the spring. The
incubation period of about a month follows with the female providing
most of the care until after hatching, at which point the pair share
parental duties. While incubating the eggs, the female will leave the
nest unattended to forage several times a day (New Zealand Dept. of
Conservation).
Ducklings fledge at eight weeks, at which point
their first molt sheds their brown and white down. Males and females are
not distinguishable until the second molt when they reach sexual
maturity (New Zealand Dept. of Conservation).