White-bellied Storm-Petrel vs Black-bellied Storm-Petrel

In short

The most reliable field mark to distinguish these two storm-petrels is the presence of a bold black central belly stripe on the Black-bellied Storm-Petrel, which the White-bellied Storm-Petrel lacks. Additionally, Black-bellied Storm-Petrel has longer legs that project beyond the tail in flight, unlike the White-bellied Storm-Petrel.

Identification tips

• Look for the black central belly stripe on the Black-bellied Storm-Petrel.
• Check the leg length: Black-bellied's legs extend beyond the tail in flight, unlike White-bellied.
• Consider habitat: White-bellied is more likely in warmer waters, Black-bellied in colder, sub-Antarctic regions.

Plumage

Both species are generally grayish or blackish above with a black hood, dark upper wings and tail, and white wing linings. However, the Black-bellied Storm-Petrel has darker upperparts and a distinctive black central belly stripe, while the White-bellied Storm-Petrel has pale-tipped upperparts and lacks the belly stripe.

Behaviour

Both species forage by skipping off waves using one leg in an asymmetrical manner.

Habitat

The White-bellied Storm-Petrel prefers warmer waters and breeds in sub-tropical regions, while the Black-bellied Storm-Petrel prefers colder waters and is a true sub-Antarctic breeder.