Manu Minute: ΄Iwa, the man-of-war bird

By Patrick Hart,

Ann Tanimoto-Johnson, Savannah Harriman-Pote

Published December 27, 2021 at 1:25 PM HST

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1 of 2 — Image 1: ΄Iwa in flight

When in flight, ΄iwa, or great frigatebirds, have immediately recognizable silhouettes with long, pointed wings, hooked bills, and a forked tail. ΄Iwa have the largest wings for their body weight of any bird in the world, and recent studies using satellite transmitters have shown they can fly over two months without landing.

Ann Tanimoto-Johnson

2 of 2 — Image 2: ΄Iwa at the Hawaii Wildlife Center

΄Iwa are sexually dimorphic. Like many birds, males and females differ in size and coloration. But their most notable difference is far more unique: males have bright red gular sacs or “pouches” under their bills which inflate during courtship displays, while females have white-colored gular sacs that do not inflate.

Alex Wang

΄Iwa, also known as great frigatebirds, live their lives far above our heads. These birds can soar for hours, days, and even months, without landing. They even have the ability to sleep while in flight!

΄Iwa get a bad rap for their feeding behaviors. They'll use their natural agility to harass other seabirds into dropping their food, which ΄iwa can then scavenge. This practice of "kleptoparasitism" earned them the name ΄iwa, which can translate to "thief," as well as the nickname “man-of-war bird." Despite their reputation, great frigatebirds do catch a majority of their own meals.

Listen to our Manu Minute to hear more about the conservation and cultural significance of the ΄iwa!

AMTJ_Manu Minute Iwa, spectrogram video.mp4

Audio credit: Chandler Robbins/Macaulay Library at the Cornell Lab of Ornithology (ML32597)