Matsudaira's Storm-Petrel vs Bulwer's Petrel

Matsudaira's Storm-Petrel and Bulwer's Petrel can be distinguished primarily by size and plumage. Matsudaira's is larger with a more robust build, while Bulwer's is slimmer with a distinct tail shape. Both species are dark, but Matsudaira's has a more uniform dark plumage compared to Bulwer's slightly browner tones.

Look for Matsudaira's Storm-Petrel's larger size and uniform dark plumage. Bulwer's Petrel is slimmer with a distinctive long, wedge-shaped tail. Observe flight patterns: Bulwer's has a more buoyant and graceful flight. Consider location and range if known.

Matsudaira's Storm-Petrel is generally larger and more robust than Bulwer's Petrel, which is slimmer and more delicate.

Matsudaira's Storm-Petrel has a uniform dark plumage, while Bulwer's Petrel may appear slightly browner, especially in good light.

Both species are pelagic and spend much of their time at sea, but Bulwer's Petrel is known for its more graceful flight pattern.

Both species are oceanic, but Bulwer's Petrel is more widespread, breeding on islands across the Atlantic and Pacific, while Matsudaira's is more restricted to the Northwest Pacific.

Vocalizations are not a reliable field mark as both species are mostly silent at sea.