Spectacled Petrel vs Great Shearwater

The Spectacled Petrel and Great Shearwater can be distinguished by their head markings and underwing patterns. The Spectacled Petrel features distinctive white 'spectacles' around the eyes, while the Great Shearwater has a dark cap and a white underwing with variable brown markings.

1. Look for white 'spectacles' around the eyes: This is a key feature of the Spectacled Petrel. 2. Check the underwing pattern: The Great Shearwater has a white underwing with brown markings, unlike the Spectacled Petrel. 3. Observe the head markings: The Great Shearwater has a dark cap, which can help differentiate it from the Spectacled Petrel.

The Spectacled Petrel is noted for its unique white 'spectacles' around the eyes, contrasting with its otherwise dark plumage. In contrast, the Great Shearwater has a dark cap, a brown belly-patch, and a white underwing with variable brown markings.