Hawaiian Petrel vs Bonin Petrel

The Hawaiian Petrel and Bonin Petrel are both medium-sized seabirds of the Pacific, but they can be distinguished by their plumage and structure. The Hawaiian Petrel has a darker, more uniform appearance with a distinct dark cap and white forehead, while the Bonin Petrel shows a more contrasting pattern with a white face and a dark eye patch. Both species are often seen at sea, but their vocalizations and breeding habitats differ.

Look for the dark cap and white forehead of the Hawaiian Petrel versus the white face with dark eye patch of the Bonin Petrel. Note the slightly larger size and more robust build of the Hawaiian Petrel. Listen for the distinct calls at breeding sites, especially if near Hawaiian Islands.

Both species are similar in size, but the Hawaiian Petrel is slightly larger and more robust compared to the more slender Bonin Petrel.

The Hawaiian Petrel has a dark cap and nape with a contrasting white forehead and underparts, giving it a more uniform dark appearance. In contrast, the Bonin Petrel has a white face with a distinct dark eye patch, and its underparts are also white, creating a more contrasting look.

Both species are pelagic and spend most of their time at sea, feeding on squid and fish. The Hawaiian Petrel is known to forage more during crepuscular periods, while specific foraging behavior of the Bonin Petrel is less documented.

The Hawaiian Petrel breeds on high-elevation slopes in the Hawaiian Islands, whereas the Bonin Petrel breeds on islands in the Northwestern Hawaiian Islands and other Pacific islands. Both species are affected by introduced predators.

The Hawaiian Petrel is known for its eerie, wailing calls at breeding colonies, while the Bonin Petrel's vocalizations are less documented but are described as softer and less haunting.