Townsend's Storm-Petrel vs Ainley's Storm-Petrel

Townsend's Storm-Petrel and Ainley's Storm-Petrel are very similar in appearance, making them difficult to distinguish in the field. Both species have subtle size and plumage differences, but these are not well-documented. Their non-breeding distributions overlap, adding to the challenge of identification.

Due to the lack of well-documented differences, focus on the location and time of year, as Townsend's Storm-Petrel disperses both north and south from southern California, while Ainley's Storm-Petrel is thought to migrate south near the Galapagos.

Both species have subtle plumage differences, but specific details are not well-documented. They are generally similar in appearance.