Leach's Storm-Petrel vs Sooty Shearwater

In short

Leach's Storm-Petrel and Sooty Shearwater are both seabirds, but they differ significantly in size and flight style. Leach's Storm-Petrel is much smaller and exhibits a fluttering flight, while the larger Sooty Shearwater has a more powerful, gliding flight. These differences are the most reliable field marks when observing these species at sea.

Identification tips

1. Size and flight style: Note the smaller size and fluttering flight of Leach's Storm-Petrel compared to the larger, gliding Sooty Shearwater. 2. Plumage: Look for the white rump patch on Leach's Storm-Petrel, absent in Sooty Shearwater. 3. Habitat: Consider the location; Leach's Storm-Petrel is often further offshore. 4. Vocalizations: Listen for any sounds, though both are generally quiet at sea.

Size

Leach's Storm-Petrel is significantly smaller than the Sooty Shearwater, with a wingspan of about 20-24 inches compared to the Sooty Shearwater's 37-40 inches.

Plumage

Leach's Storm-Petrel is mostly dark with a distinctive white rump patch, whereas the Sooty Shearwater is uniformly dark sooty brown with a silvery underwing.

Behaviour

Leach's Storm-Petrel has a fluttering, erratic flight pattern, often hovering over the water, while the Sooty Shearwater is known for its strong, direct flight with long glides.

Habitat

Both species are pelagic, but Leach's Storm-Petrel is more likely to be found further offshore, while Sooty Shearwaters can be seen closer to shore, especially during migration.

Voice

Leach's Storm-Petrel is generally silent at sea, while the Sooty Shearwater may produce low croaking or moaning sounds, though vocalizations are rarely heard during field observations.