More about the great frigatebird, or ʻiwa

The great frigatebird, or ʻiwa in Hawaiian, is one of the easiest birds to identify at Kīlauea Point NWR, due to its distinctly different look from the other birds here. This large black bird, with its seven-foot wingspan, forked tail, narrow, angled wings and light body, is an aerodynamic wonder.

The weight of the bones makes up a mere 5% of its total body weight and who needs legs when you’ve got wings? The legs and feet are so trimmed down to size that on land `iwa can do little more than perch on branches or a cliff; they really don’t walk. An ‘iwa that lands on the ground struggles to get back onto its perch. Landing on the ocean is even more dangerous because, unlike most seabirds, they cannot run on the ocean because of those diminutive legs and feet. A poorly developed oil gland means minimal waterproofing on their feathers. Landing on the ocean for this bird could lead to becoming waterlogged and drowning.

Oh, but what supreme fliers they are! Scientists have discovered that frigatebirds can stay aloft for nearly 2 months at a time and reach heights as high as 2.5 miles above sea level with no problem flying through clouds or freezing temperatures! A frigatebird will end up spending up to 90% of its time in the air over its lifetime and that means there had to be some trade-offs.

Frigatebirds are also sometimes called Man-o-war birds, a name given to them by Caribbean sailors who likened them to the speedy, maneuverable pirate ships by the same name. The Hawaiian word ‘iwa means “thief” in Hawaiian and it reflects the frigatebird’s habit of stealing food from other seabirds.

This behavior, also known as kleptoparasitism, is commonly observed at Kīlauea Point where ‘iwa can be seen chasing and harassing red-footed boobies until they throw up their meal. The ‘iwa then swoops down to catch the ejected prize from mid-air and swallows it. This feeding behavior is opportunistic and not their primary hunting strategy. Most meals are caught by swooping over the water and snatching squid or fish from within a few centimeters of the ocean surface, or from the air when fish leap out of the water.

As common as it is to see ‘iwa at Kīlauea Point, they are not known to be nesting on the Refuge. In Hawai‘i, frigatebirds nest on the remote atolls and islands northwest of the main Hawaiian islands.

The most iconic image of the great frigate bird is probably that of the male, which is all black with its throat pouch, also known as a gular sac, inflated out like a great crimson red balloon during courtship. Females have a gular sac too, but it is dull in color and they do not inflate it like the males. Females can easily be distinguished from the males by their white throat and chest patch. Juveniles have white with varying amounts of rust coloring on the head, throat and underbelly.

The feathers of the ‘iwa bird features prominently in Hawaiian culture. The iridescent black feathers, including tail feathers, were used in the kāhili of royalty and in feather capes. It is found in many traditional Hawaiian moʻolelo (stories) and ʻōlelo noʻeau (sayings). One such saying, found in Mary Kawena Pukui’s book ‘Ōlelo No‘eau, says “Kīkaha ka ‘iwa he lā makani”, which translates to “When the ‘iwa bird soars on high, it is going to be windy.” Interestingly enough, when Hurricane Iniki struck in 1992, one of the staff at Kīlauea Point, who stayed on the refuge during the storm, said that early in the morning and before the winds picked up, he saw a huge flock of ‘iwa spiral up into the sky and fly northwest out to sea. The red-footed boobies, however, did not attempt to leave until the storm was upon them which resulted in a number of them being blown back into the trees and shrubs and a number of them became entangled and died.

If you want to see the ‘iwa birds on Kaua‘i, Kīlauea Point is the place to come, especially to observe them at their thieving best. Kāhili Beach is another great place to watch them too. There, you can see them swooping down to grab a quick drink from Kīlauea Stream. Whatever you do, don’t point your finger at them or you’ll make it say the keiki to one another on school field trips out to Kīlauea Point. So, grab your binoculars and come have a look, but no pointing...better to be safe than sorry.

male iwa flying Gene McGuire 5.2.11 022.jpg