Grey-backed Storm-Petrel vs Black-bellied Storm-Petrel

In short

The Grey-backed Storm-Petrel and Black-bellied Storm-Petrel can be distinguished by their belly markings and leg length. The Grey-backed has a uniformly grey belly, while the Black-bellied features a distinctive black central belly stripe. In flight, the Black-bellied's legs extend beyond the tail, unlike the Grey-backed.

Identification tips

1. Look for the black belly stripe on the Black-bellied Storm-Petrel. 2. Observe the leg length in flight; the Black-bellied's legs extend beyond the tail. 3. Consider habitat; the Black-bellied is more likely in colder waters. 4. Note the overall size; the Black-bellied is slightly larger.

Size

Both species are small storm-petrels, but the Black-bellied Storm-Petrel is slightly larger.

Plumage

The Grey-backed Storm-Petrel has a consistent grey back and belly, while the Black-bellied Storm-Petrel has a bold black stripe down the center of its white belly. Both have dark upperwings and tails.

Behaviour

Both species exhibit the typical storm-petrel foraging behavior of 'walking' on water, but the Black-bellied Storm-Petrel is noted for its unique asymmetrical skipping using one leg.

Habitat

The Grey-backed Storm-Petrel is generally found in temperate waters, whereas the Black-bellied Storm-Petrel prefers colder, sub-Antarctic waters.