Sarcidiornis melanota

The Comb Duck is unmistakable with its large size, measuring 56 to 76 cm in length, and its characteristic bulbous black knob on the male's bill. Adult males are particularly striking with glossy, iridescent plumage that appears black and greenish-blue, depending on the light. Females, on the other hand, are smaller and lack the prominent knob, displaying more subdued coloration with mottled patterns on their wings and body.

Juveniles resemble females but can be distinguished by their duller plumage and less prominent facial markings. The Comb Duck can be confused with other large waterfowl, such as geese, but its unique bill and iridescence set it apart. In flight, its strong, direct wingbeats and broad wings are distinctive. When perched or resting, the Comb Duck maintains a relaxed posture, often seen with its head tucked under its wing while floating on water.

The sexual dimorphism in this species is pronounced, with males being not only larger but also more colorful. During the breeding season, the differences become even more apparent, as males exhibit more vibrant plumage and the knob becomes more pronounced as part of their display to attract females.

Comb Ducks have an omnivorous diet, with a preference for aquatic vegetation, seeds, and small invertebrates. They often feed on the water surface, dabbling and tipping up to access underwater food sources. During the wet season, they consume a greater proportion of plant material, such as grasses and sedges, which are abundant in flooded areas.

In the dry season, when plant availability decreases, their diet shifts towards insects and other invertebrates, which they skillfully capture with their broad bills. They are known to feed during both day and night, though they are generally more active at dawn and dusk. Their foraging behavior is efficient, often involving group feeding where multiple individuals work together to locate and capture prey.

Comb Ducks are social birds, often forming small flocks outside the breeding season. During courtship, males display by expanding their necks, showcasing their bright plumage, and vocalizing to attract females. These displays can be quite elaborate, involving head shaking and wing flapping to draw attention.

Territorial behavior is minimal, with Comb Ducks showing tolerance towards conspecifics, especially in areas with abundant resources. They are generally non-aggressive, although males may exhibit some competition during the breeding season. In response to predators, Comb Ducks rely on their strong flight ability, taking to the air with little hesitation when threatened. Daily activity patterns include periods of feeding interspersed with resting and preening, often conducted in the safety of open water.

The nesting habits of the Comb Duck involve selecting locations near water sources, often utilizing dense vegetation or secluded areas for concealment. Nests are typically constructed using locally available materials such as grasses, reeds, and leaves, forming a simple but effective structure.

Clutch size ranges from 6 to 15 eggs, with incubation lasting approximately 28 to 30 days. Both parents participate in rearing the young, although the female primarily incubates the eggs. After hatching, ducklings remain with the parents until they fledge, which occurs around 8 to 10 weeks of age. The Comb Duck generally produces one brood per year, though in optimal conditions, a second brood may be attempted.

The vocalizations of the Comb Duck are not particularly musical but serve important social functions. Their primary call is a low, grating sound, often described as a 'gurr' or 'grog,' used for communication within flocks. During the breeding season, males emit a series of softer, more melodic whistles as part of their courtship display. Alarm calls are sharp and abrupt, helping alert others to potential danger. While not prolific singers, their calls are essential for maintaining social bonds and coordinating group movements.

• 1Comb Ducks have one of the most striking sexual dimorphisms among waterfowl, with males sporting a prominent black knob on their bills.
• 2Despite their large size, Comb Ducks are strong fliers, capable of covering great distances in search of suitable habitats.
• 3The iridescence of the male Comb Duck's plumage changes with the angle of light, creating a spectacular array of colors.
• 4Comb Ducks often engage in communal nesting, where several females may lay eggs in the same nest, increasing the brood's survival chances.
• 5The species gets its name from the comb-like knob on the male's bill, which is most noticeable during the breeding season.
• 6Comb Ducks play a crucial role in seed dispersal, contributing to the health and regeneration of wetland ecosystems.
• 7Historically, the Comb Duck was considered a sacred symbol in various cultures, often associated with fertility and abundance.

The Comb Duck is currently listed as Least Concern by the IUCN, with populations considered stable across much of its range. However, localized threats persist, including habitat loss due to wetland drainage and conversion for agriculture. Pollution and hunting also pose risks in some areas. Conservation efforts focus on protecting wetland habitats and promoting sustainable land use practices to ensure the long-term survival of the species. Historically, Comb Duck populations have fluctuated in response to environmental changes, but adaptive conservation measures have helped mitigate severe declines.