Arctic Skua vs Brown Skua

In short

The Arctic Skua (Stercorarius parasiticus) and Brown Skua (Stercorarius antarcticus) can be challenging to differentiate, especially in non-breeding plumages. The Arctic Skua is generally smaller and more variable in plumage, while the Brown Skua is larger and more uniformly dark. Observing their behavior and habitat can also aid in identification.

Identification tips

1. Size and Structure: Look for the smaller, more slender Arctic Skua versus the larger, bulkier Brown Skua. 2. Plumage: Note the contrasting morphs in Arctic Skuas compared to the uniform dark brown of Brown Skuas. 3. Behavior: Observe kleptoparasitic behavior in Arctic Skuas and more aggressive scavenging in Brown Skuas. 4. Habitat: Consider the geographical location; Arctic Skuas are more northern, while Brown Skuas are found in the southern hemisphere.

Size

The Arctic Skua is smaller and more slender compared to the larger and bulkier Brown Skua.

Plumage

Arctic Skuas exhibit two morphs: dark and light, with intermediate forms, often showing more contrast in plumage. Brown Skuas are typically uniformly dark brown, lacking the distinct morphs seen in Arctic Skuas.

Behaviour

Arctic Skuas are known for kleptoparasitism, often harassing other birds for food. Brown Skuas are more aggressive predators and scavengers, feeding on carrion, eggs, and vulnerable birds.

Habitat

Arctic Skuas breed in the Arctic and subarctic regions, often seen at sea during migration. Brown Skuas are found in subantarctic regions, both at sea and on land.