Understandably also known as Knob-billed Ducks, the unusual Comb Ducks are named for the
prominent, leaf-shaped caruncle
or fatty comb atop the basal two-thirds of the drake's black bill, a
structure clearly evident even in flight. While flaccid and reduced in size
for much of the year, the fleshy comb enlarges considerably prior to the breeding season,
when caruncle size presumably indicates the general vigor of males.
Drakes are twice the size of females, and their dark dorsal
surfaces are glossed with dazzling metallic-violet, purple, bronze and green.
Male vents and flanks are enhanced with pronounced yellow or cinnamon,
and their creamy-white head and hindneck is washed with orange-yellow.
The extent of black on their head is highly variable; some males are nearly black
headed. Both sexes possess a small crest of slightly curly feathers,
but the less glossy females lack a
comb and yellowish head coloration, and their head is
normally more profusely spotted.
While widely separated geographically, the two races are quite similar,
but some taxonomists regard them as separate species.
Possibly originating from African immigrants crossing the Atlantic,
the slightly smaller, more elongated South American Comb Duck
(S. m. sylvicola) drakes show significantly blacker,
non-glossy flanks than Old World Comb Ducks (S. m. melanotos),
and the more speckled females tend to be darker.
Heavily built, goose-like ducks of wooded wetlands,
the African birds are partial to grassy savanna
woodlands featuring lagoons or inundated areas.
Though primarily lowland residents, the neotropical
ducks reportedly occur as high as 11,500 feet.
Chiefly sedentary in Asia and South America, seasonal
movements are mostly related to dry season water availability.
The highly mobile African ducks are
prone to undertake extensive journeys that occasionally surpass 2,200 miles.
Habitually perching in
trees (particularly dead ones),
Comb Ducks reportedly even cling with their strong claws to vertical
tree trunks like monstrous woodpeckers.
Resorting to the wing immediately when disturbed they fly on
slow but steady, noisy wingbeats,
with flocks traveling in irregular formation,
staggered single-file lines, or V-formation.
South American Comb Duck. Commonly seen alone or in small parties,
the rather shy ducks gather into
flocks that may exceed a hundred non-breeding birds during the dry season,
sometimes in sexually
Comb Ducks commonly roost on the ground along neotropical rivers,
and they may associate with other waterfowl.