Elliot's Storm-Petrel vs Least Storm-Petrel

In short

Elliot's Storm-Petrel and Least Storm-Petrel can be challenging to differentiate at sea. The most reliable field mark is the rump pattern: Elliot's has a white rump with a central dark line, while Least has a uniform dark rump. Both species are small, dark storm-petrels, but their flight patterns and habitats can also offer clues.

Identification tips

1. Look for the white rump with a central dark line on Elliot's Storm-Petrel; Least has a uniform dark rump. 2. Note the flight pattern: Elliot's has a fluttering flight, while Least is more direct. 3. Consider the location: Elliot's is more likely in the Humboldt Current, Least in the eastern Pacific near Baja California.

Size

Both species are small, but the Least Storm-Petrel is slightly smaller and more compact than Elliot's Storm-Petrel.

Plumage

Elliot's Storm-Petrel has a distinctive white rump with a central dark line, whereas the Least Storm-Petrel has a uniform dark rump. Both have dark upperparts and underparts.

Behaviour

Elliot's Storm-Petrel tends to have a more erratic, fluttering flight compared to the faster, more direct flight of the Least Storm-Petrel.

Habitat

Elliot's Storm-Petrel is typically found in the Humboldt Current off the coasts of Peru and Chile, while the Least Storm-Petrel is more often seen in the eastern Pacific, particularly off the coast of Baja California.

Voice

Vocalizations are not typically used for identification at sea, as both species are generally silent when away from breeding colonies.