Petrel de Bulwer vs Petrel de Jouanin

Bulwer's Petrel and Jouanin's Petrel are both dark petrels with long wedge-shaped tails, but they can be distinguished by size and subtle plumage differences. Jouanin's Petrel is generally larger with a heavier bill, while Bulwer's Petrel is smaller and more slender.

Look for the size difference and bill structure first; Jouanin's Petrel is larger with a heavier bill. Check for the presence of a pale bar on the upperwing-coverts, which is more likely in Jouanin's Petrel.

Jouanin's Petrel is larger and has a heavier bill compared to the more slender Bulwer's Petrel.

Both species are sooty-brown to blackish-brown, but Jouanin's Petrel may show a weak pale bar on the upperwing-coverts, which is less pronounced in Bulwer's Petrel.