Hawaiian Petrel vs Cook's Petrel

In short

Hawaiian Petrel and Cook's Petrel are both medium-sized seabirds of the genus Pterodroma, but they can be distinguished by differences in plumage and structure. Hawaiian Petrel has a more robust build with a darker overall appearance, while Cook's Petrel is slimmer and paler. Observing these differences in flight or at sea can help in identification.

Identification tips

1. Look for the darker, more robust appearance of the Hawaiian Petrel compared to the paler, slimmer Cook's Petrel. 2. Note the contrasting white belly of the Hawaiian Petrel against its blackish upperparts. 3. Consider geographic location and range, as Hawaiian Petrel is more likely in the central Pacific, while Cook's Petrel is found further south.

Size

Hawaiian Petrel is slightly larger and more robust compared to the slimmer Cook's Petrel.

Plumage

Hawaiian Petrel has a darker plumage overall, with a blackish head and upperparts, and a contrasting white belly. Cook's Petrel is paler, with a more uniform gray upperparts and a less contrasting white underbelly.

Behaviour

Both species exhibit similar flight patterns typical of gadfly petrels, with dynamic and agile flight. Specific behavioral differences are not well-documented.

Habitat

Hawaiian Petrel is primarily found in the central Pacific, breeding in the Hawaiian Islands, while Cook's Petrel breeds on islands off New Zealand and ranges across the South Pacific.

Voice

Vocalizations are not a reliable field mark as both species are rarely heard at sea and their calls are more often noted at breeding sites.