Northern Giant-Petrel vs Grey-faced Petrel

In short

The Northern Giant-Petrel (Macronectes halli) and Grey-faced Petrel (Pterodroma gouldi) can be differentiated by size and bill structure. The Northern Giant-Petrel is significantly larger with a robust, pale bill, while the Grey-faced Petrel is smaller with a more slender, dark bill. Both species are seabirds, but their habitats and behaviors differ, aiding in identification.

Identification tips

• Size and shape: Look for the larger size and robust build of the Northern Giant-Petrel.
• Bill structure: Note the pale, massive bill of the Northern Giant-Petrel compared to the slender, dark bill of the Grey-faced Petrel.
• Plumage: Observe the mottled grey-brown plumage of the Northern Giant-Petrel versus the uniform dark grey of the Grey-faced Petrel.
• Behavior: Watch for scavenging behavior and association with ships in Northern Giant-Petrels.
• Location: Consider the geographic location; Northern Giant-Petrels are more likely in colder waters.

Size

The Northern Giant-Petrel is much larger, resembling a small albatross, whereas the Grey-faced Petrel is medium-sized for a petrel.

Plumage

Northern Giant-Petrels have a mottled grey-brown plumage with a pale head and neck, while Grey-faced Petrels are uniformly dark grey with a paler face.

Behaviour

Northern Giant-Petrels are often seen scavenging and following ships, whereas Grey-faced Petrels are more solitary and less likely to approach vessels.

Habitat

Northern Giant-Petrels are typically found in subantarctic and Antarctic waters, while Grey-faced Petrels are more common in temperate and subtropical seas, particularly around New Zealand.

Voice

Vocalizations are not a reliable field mark for these species as they are rarely heard at sea.