Knob-billed Duck vs Cotton Pygmy-Goose

In short

The Knob-billed Duck and Cotton Pygmy-Goose can be distinguished by their size and bill features. The Knob-billed Duck is larger and has a distinctive knob on its bill, while the Cotton Pygmy-Goose is smaller with a more delicate bill. Both species inhabit wetlands, but the Cotton Pygmy-Goose prefers areas with abundant floating vegetation.

Identification tips

• Size: The Knob-billed Duck is larger.
• Bill: Look for the distinctive knob on the Knob-billed Duck's bill.
• Plumage: Note the contrasting black and white plumage of the Knob-billed Duck versus the more subtle coloration of the Cotton Pygmy-Goose.
• Behavior: Observe flocking behavior; the Cotton Pygmy-Goose is more likely to be seen in large groups.

Size

The Knob-billed Duck is significantly larger than the Cotton Pygmy-Goose.

Plumage

The Knob-billed Duck has a more contrasting black and white plumage, with a glossy greenish or purplish sheen on the back. The Cotton Pygmy-Goose is more subtly colored, with a greenish back and white underparts.

Behaviour

The Knob-billed Duck is often seen alone or in small groups, while the Cotton Pygmy-Goose is more social, forming flocks of hundreds outside the breeding season.

Habitat

Both species are found in wetlands, but the Cotton Pygmy-Goose specifically prefers areas with abundant floating or submerged vegetation.