Lesser Frigatebird vs Christmas Island Frigatebird

In short

The Lesser Frigatebird and Christmas Island Frigatebird are both large seabirds with long, forked tails and slender, hooked bills. The most reliable field mark is the underwing pattern: Lesser Frigatebirds have a narrower white bar on the underwing compared to the broader white bar of the Christmas Island Frigatebird. Both species can be seen together in their overlapping ranges, making careful observation essential.

Identification tips

• Underwing pattern: Look for the width of the white bar; narrower in Lesser Frigatebird.
• Size: Lesser Frigatebird is smaller.
• Range overlap: Be aware of overlapping ranges, especially near Christmas Island.
• Age and sex: Consider plumage variations due to age and sex, which can complicate identification.

Size

The Lesser Frigatebird is the smallest frigatebird species, while the Christmas Island Frigatebird is slightly larger, though both are large birds overall.

Plumage

Lesser Frigatebirds have a narrower white bar on the underwing, whereas Christmas Island Frigatebirds display a broader white bar. Both species have similar dark plumage otherwise.

Behaviour

Both species exhibit typical frigatebird behavior, soaring with minimal wingbeats and engaging in kleptoparasitism.

Habitat

Both species inhabit tropical and subtropical oceans, often seen soaring over open water near islands.