Antarctic Prion vs Slender-billed Prion

In short

Antarctic Prion and Slender-billed Prion are both small seabirds with subtle differences. The most reliable field mark is the bill shape: Antarctic Prion has a broader, more robust bill compared to the slender, more pointed bill of the Slender-billed Prion. Both species have similar plumage, making bill shape a key identifier.

Identification tips

1. Bill Shape: Look for the broader bill of the Antarctic Prion versus the slender bill of the Slender-billed Prion. 2. Plumage: Note that plumage is similar; rely on bill shape instead. 3. Location: While both species share similar ranges, slight variations in distribution might help if known. 4. Behavior: Observe flight and feeding behavior, though these are not distinctive.

Size

Both species are similar in size, with no significant difference to note in the field.

Plumage

Both prions have similar grey and white plumage, with a blue-grey upper and white underparts. Plumage alone is not a reliable differentiator.

Behaviour

Both species exhibit similar flight patterns and feeding behaviors, often seen skimming low over the water.

Habitat

Both species are pelagic and are often found in similar southern oceanic waters, making habitat a non-distinctive factor.

Voice

Vocalizations are not well-documented for field differentiation between these two species.