ʻIwa – Great Frigatebird
Fregata minor
| Stated-recognized | Indigenous |
| NatureServe Heritage Rank | G4 – Apparently secure |
| North American Waterbird Conservation Plan |
Moderate Concern |
| Regional Seabird Conservation Plan |
USFWS 2005 |
The ‘iwa or great frigatebird is a large, graceful seabird (Family: Fregatidae) related to boobies and tropicbirds, with a pantropical distribution. Five ‘iwa (great frigatebird) subspecies are recognized, and one (F. m. palmerstoni) breeds in Hawai‘i.
Individuals have slim bodies, a long deeply forked tail, a long hooked bill, and almost useless legs and feet. Adult males are almost entirely black, with varying amounts of a dark green sheen on head and neck; during courtship males inflate large, red gular pouch. Adult females are larger than males, and are black with a white breast patch and a gray throat; both sexes may have a buff bar on the upper surface of wings. Flight is characterized by long periods of soaring.
An adept aerial flier, the species obtains some of its food by harassing other seabirds until they regurgitate their prey. Although ‘iwa (great frigatebird) captures most of its own prey, this behavior inspired both its Hawaiian and English names: ‘iwa means “thief” and “frigate” refers to the fast ships used by pirates. Often feeds far from land alone or in pairs, but will join mixed species feeding flocks, especially ‘ewa‘ewa or sooty terns (Sterna fuscatata) and ‘ua‘u kani or wedge-tailed shearwaters (Puffinus pacificus), feeding over schools of predatory fishes. ‘Iwa (great frigatebird) take prey on the wing, seizing it by dipping bill into water or from the air.
In Hawai‘i, diet primarily consists of flyingfish and squid. Nests in colonies, often with other species, ranging from ten to thousands of pairs, and constructs platform nests in low bushes. Unlike many seabirds, pairs usually switch partners every breeding season, likely because females often only nest every two to four years. Both parents incubate single egg, and brood and feed chick. Post-fledging feeding is provided by female for up to 18 months. Birds first breed at eight to ten years of age, and the oldest known individual was 37 years old.
‘Iwa (great frigatebird) breed throughout the NWHI. Large numbers roost on offshore islets of the MHI, but breeding has not been documented. Outside of Hawai‘i, ‘iwa (great frigatebird) nest on islands mainly in the tropical Atlantic, Indian, and Pacific oceans.
Outside the breeding season, adults remain relatively close to breeding colonies, but young and nonbreeders disperse throughout tropical oceans.
The Great Frigatebird, or ‘Iwa, can be found in all areas of Green Island. Often seen flying high over head, these prehistoric-looking birds are easy to spot on Kure Atoll. Great Frigatebirds build their nests in the tops of various species of bushes and trees, including beach naupaka and beach heliotrope. They are most often found nesting in the heliotrope trees along the north end of the island, though they can been seen perched in the naupaka bushes in all areas of Green Island. With that said, they are a bit shy and do not often frequent camp.
LOCATION AND CONDITION OF KEY HABITAT: Terrestrial: ‘Iwa (great frigatebird) breed and roost on small remote islands, typically within regions with tradewinds. Builds nests in the tops of various species of bushes and trees, including beach naupaka (Scaevola sericea), beach heliotrope (Tournefortia argentea), pisonia trees (Pisonia grandis), and mangrove trees (Brugiera spp., Rhizophora spp.) Marine: Pelagic.
The following management goals are important to Pacific seabird conservation: maintain, protect, and enhance habitat; eradicate or control non-natives; minimize bycatch and other negative effects of fishing; improve the effectiveness of oil spill response efforts; identify contaminates and hazardous substances; and minimize the effects of powerlines, towers, wind turbines and lights (USFWS 2005). The goal of these management actions is not only to protect seabird populations and their breeding colonies, but also to re- establish former breeding colonies thereby reducing the risk of extinction.
Kumulipo: Hawaiian Creation Chant
Hanau ka Moho, he makua
Born was the Rail, the parent
Puka kana keiki he Moli, lele
Out came its child a brown Albatross, and flew
-Line 311-312
ʻŌlelo Noʻeau
Fig., thief, so called because it steals food by forcing other birds to disgorge; also used figuratively for a handsome person, as follows: Kīkaha ka ʻiwa, he lā makani, poises the frigate bird, a windy day [of a handsome person who draws attention, as does the ʻiwa bird poised aloft]. Ka ʻiwa ālai maka, the frigate bird that fascinates the eye [an attractive person]. He iwa ka hoa e like ai (Kel. 134), just like one’s friend the ʻiwa bird (of one dressed up in finery).
ʻiwa
1. Frigate or man-of-war bird (Fregata minor palmerstoni); it has a wing span of 12 m. See ex., maʻoha; see sayings, ʻānai, haehae 2. (PCP kiwa.)
2. A native fern (Asplenium horridum) with narrow, feather-shaped fronds 45 to 95 cm long, their dark stems bearing dark-brown hairs and scales. The stems were formerly used for making hats. Also ʻalae. (PCP kiwa.)
