Hawaiian Petrel vs Bulwer's Petrel

The Hawaiian Petrel and Bulwer's Petrel can be distinguished by size and plumage. Hawaiian Petrels are larger and have a distinctive dark cap and white underparts, while Bulwer's Petrels are smaller and uniformly dark. Observing these features in flight or at sea can help differentiate them.

Look for the size difference first; Hawaiian Petrels are noticeably larger. Check for the contrasting plumage of Hawaiian Petrels with their white underparts and dark cap. Observe flight style; Hawaiian Petrels have a more direct flight compared to the fluttering of Bulwer's Petrels. Listen for eerie moaning calls at breeding sites for Hawaiian Petrels.

Hawaiian Petrel is larger, with a wingspan of about 100 cm, compared to the smaller Bulwer's Petrel, which has a wingspan around 76 cm.

Hawaiian Petrel has a dark cap, white underparts, and a contrasting dark back and wings. Bulwer's Petrel is uniformly dark brown, lacking the contrasting plumage of the Hawaiian Petrel.

Both species are pelagic and spend much of their time at sea. Hawaiian Petrels are known for their powerful, direct flight, while Bulwer's Petrels have a more fluttering flight pattern.

Hawaiian Petrels breed in the Hawaiian Islands, often in high-elevation areas, while Bulwer's Petrels are more widespread, breeding on islands in the Atlantic and Pacific Oceans.

Hawaiian Petrels are known for their eerie, moaning calls at breeding sites, whereas Bulwer's Petrels are generally silent at sea, with some vocalizations at colonies.