Arctic Skua vs South Polar Skua

Arctic Skua (Stercorarius parasiticus) and South Polar Skua (Stercorarius maccormicki) can be challenging to differentiate, especially in their dark morphs. The Arctic Skua is generally smaller and more agile, while the South Polar Skua often shows colder plumage tones without rufous and a distinctive white 'skua flash' on the wings. Both species exhibit kleptoparasitic behavior, but their habitats and breeding ranges differ significantly.

1. Size and agility: Arctic Skua is smaller and more agile. 2. Plumage tones: Look for cold tones and absence of rufous in South Polar Skua. 3. Wing markings: South Polar Skua shows a white 'skua flash' on the wings. 4. Nape color: Adult South Polar Skua has a buffy yellow nape. 5. Habitat: Consider the geographical location; Arctic Skua is found in the northern hemisphere, South Polar Skua in the Antarctic.

Arctic Skua is generally smaller and more agile compared to the larger South Polar Skua.

Arctic Skua has two morphs, dark and light, with intermediate forms, while South Polar Skua's dark morph is distinguished by cold tones and lacks rufous. South Polar Skua also has a white 'skua flash' along the primary bases and a buffy yellow nape in adults.

Both species engage in kleptoparasitism, but Arctic Skua is more studied in this behavior in the northeast Atlantic.

Arctic Skua breeds in the northern hemisphere, particularly in the Arctic, while South Polar Skua breeds in the Antarctic region.