Herald Petrel vs Black-winged Petrel

In short

The Herald Petrel and Black-winged Petrel are both medium-sized petrels with similar plumage, making them challenging to distinguish at sea. The most reliable field mark is the underwing pattern: the Herald Petrel typically shows a more contrasting black and white underwing, whereas the Black-winged Petrel has a more uniformly dark underwing with less contrast.

Identification tips

1. Focus on the underwing pattern: Herald Petrel has a more contrasting black and white underwing. 2. Note the overall body shape: Black-winged Petrel may appear slightly more slender. 3. Consider the location and time of year, as ranges may overlap but can provide context.

Size

Both species are similar in size, but the Black-winged Petrel may appear slightly more slender.

Plumage

Herald Petrels have a more contrasting black and white underwing pattern, while Black-winged Petrels have a darker, less contrasting underwing. The upperparts of both species are generally similar, with a greyish tone.

Behaviour

Both species exhibit similar flight patterns typical of petrels, with gliding and occasional flapping. Behavior is not a reliable differentiator.

Habitat

Both species are pelagic and are often found in similar oceanic habitats, making habitat an unreliable differentiator.

Voice

Vocalizations are not well-documented for field identification and are not a reliable differentiator.