Grey-backed Storm-Petrel vs White-bellied Storm-Petrel

In short

To distinguish the Grey-backed Storm-Petrel from the White-bellied Storm-Petrel, focus on the plumage and behavior. The Grey-backed Storm-Petrel has a distinctive grey back, while the White-bellied Storm-Petrel features predominantly white underparts and lacks a central black belly stripe. Both species exhibit unique foraging behaviors, but the Grey-backed Storm-Petrel's grey coloration is a key identifier.

Identification tips

1. Look for the grey back of the Grey-backed Storm-Petrel. 2. Note the white underparts and lack of a central belly stripe in the White-bellied Storm-Petrel. 3. Observe foraging behavior; the White-bellied Storm-Petrel's one-legged skip is distinctive. 4. Consider the habitat: warmer waters suggest White-bellied Storm-Petrel.

Size

Both species are similar in size, typical of small storm-petrels.

Plumage

The Grey-backed Storm-Petrel has a grey back and darker upperparts, whereas the White-bellied Storm-Petrel is characterized by white underparts and lacks a central black belly stripe. The White-bellied Storm-Petrel also has pale-tipped upper parts.

Behaviour

Both species forage by skipping off waves, but the White-bellied Storm-Petrel is noted for its asymmetrical skipping using one leg.

Habitat

The Grey-backed Storm-Petrel is generally found in cooler waters, while the White-bellied Storm-Petrel prefers warmer, subtropical waters and breeds on scattered islands in both the Pacific and Atlantic Oceans.