Ainley's Storm-Petrel vs Ashy Storm-Petrel

In short

Ainley's Storm-Petrel and Ashy Storm-Petrel are both small, dark storm-petrels that can be challenging to differentiate. Ainley's Storm-Petrel tends to have a slightly more forked tail and longer wings, while Ashy Storm-Petrel is known for its more uniform dark plumage. Observing their behavior and habitat can also provide clues.

Identification tips

• Look for the slightly more forked tail and longer wings of Ainley's Storm-Petrel.
• Note the uniform dark plumage of Ashy Storm-Petrel.
• Consider the location: Ashy Storm-Petrel is more likely along the California coast, while Ainley's may be seen further south.
• Be aware that vocalizations are not a reliable differentiator for these species.

Size

Both species are similar in size, but Ainley's Storm-Petrel may appear slightly larger due to its longer wings.

Plumage

Ainley's Storm-Petrel has a slightly more forked tail and may show subtle differences in wing length. Ashy Storm-Petrel is more uniformly dark and lacks the forked tail appearance.

Behaviour

Both species exhibit typical storm-petrel flight patterns, but Ainley's Storm-Petrel might be seen further south near the Galapagos during migration.

Habitat

Ashy Storm-Petrel breeds along the California coast, often in protected areas, while Ainley's Storm-Petrel is less well-known but thought to migrate southward.

Voice

Vocalizations are not well-documented for either species, making it an unreliable field mark.