Sooty Swift vs Great Dusky Swift

In short

The Sooty Swift and Great Dusky Swift are both dark swifts of the Cypseloides genus, but they can be distinguished by size and head coloration. The Great Dusky Swift is larger with a distinctive silvery head, whereas the Sooty Swift is uniformly dark.

Identification tips

1. Look for the silvery head of the Great Dusky Swift, especially in good light. 2. Compare sizes if both species are present; the Great Dusky Swift will appear larger. 3. Observe behavior; the Great Dusky Swift may be seen perching on rocks, unlike the Sooty Swift. 4. Consider the location; proximity to large waterfalls may suggest Great Dusky Swift.

Size

The Great Dusky Swift is fairly large compared to the Sooty Swift, which is smaller and more compact.

Plumage

The Great Dusky Swift has a dark grayish-brown body with a silvery head, while the Sooty Swift is uniformly sooty or dark brown without the silvery head.

Behaviour

Both species are often seen in flight, but the Great Dusky Swift is known for perching on exposed rock faces, especially near waterfalls.

Habitat

The Great Dusky Swift is often associated with the dramatic torrents of Iguazu Falls and similar environments in eastern South America, whereas the Sooty Swift's habitat details are less specific in the sources.