Wilson's Storm-Petrel vs Fork-tailed Storm-Petrel

Wilson's Storm-Petrel and Fork-tailed Storm-Petrel are both small, pelagic seabirds, but they can be distinguished by their plumage and behavior. Wilson's Storm-Petrel is dark with a distinctive white rump, while the Fork-tailed Storm-Petrel has a unique bluish-gray coloration. Both species exhibit similar foraging behaviors, but their habitats and vocalizations differ.

1. Look for the white rump on Wilson's Storm-Petrel. 2. Note the bluish-gray coloration of the Fork-tailed Storm-Petrel. 3. Observe the foraging behavior: Wilson's dips feet, Fork-tailed may follow ships. 4. Consider habitat: Wilson's is more generalist, Fork-tailed prefers shelf waters.

Both species are small storm-petrels, but Wilson's Storm-Petrel is generally smaller and more compact than the slightly larger Fork-tailed Storm-Petrel.

Wilson's Storm-Petrel is mostly dark with a prominent white rump patch, whereas the Fork-tailed Storm-Petrel is characterized by its bluish-gray plumage, lacking the stark white rump.

Both species forage by hovering and pattering on the water surface. Wilson's Storm-Petrel often dips its feet into the water to disturb prey, while Fork-tailed Storm-Petrel may follow ships and is attracted to lights at night.

Wilson's Storm-Petrel is a generalist, found in various pelagic environments, while Fork-tailed Storm-Petrel is more often seen over continental shelf waters and near the shelf break.

Vocalizations are not a primary distinguishing feature in the field for these species, and specific differences are not well-documented.