Great Frigatebird

(Fregata minor)
Hawaiian Name: ʻIwa
male great frigatebird
Male adult Great Frigatebird

The Great Frigatebird is a highly mobile and wide-ranging seabird found across much of the tropical Pacific and Indian Oceans, and parts of the South Atlantic. The species breeds on most of the Northwestern Hawaiian Islands (an estimated 5,000 pairs), with the largest breeding colony found on Nihoa. A single breeding record from Mokumanu Islet off Oʻahu is the only breeding record for the Southeastern Hawaiian Islands. However, Great Frigatebirds can be found year-round in all of the Hawaiian Islands and are often seen roosting or soaring over offshore islets in large numbers, often numbering into the hundreds. On Kauaʻi, Great Frigatebirds are regularly seen at coastal locations anywhere around the island, but are easiest to see at Kilauea Point, where there are usually numerous birds soaring over the point itself, over nearby Crater Hill, or roosting on Mokuʻaeʻae Islet just north of the lighthouse.

These long-winged and highly aerial seabirds seem to float almost effortlessly in midair as they wait for other seabirds to come near. Great Frigatebirds specialize in kleptoparasitism, or the stealing of food from other birds, usually boobies. These spectacular aerial chases usually result in the unfortunate victim dropping its recent catch, which the frigatebird will then grab, often in midair. Although frigatebirds are renowned for this behavior, the majority of their food comes from snatching food off the surface of the water and catching flying fish in midair. They are incapable of landing on the water, so they spend nearly all of their time in flight. Frigatebirds, including Great Frigatebirds are capable of extremely long-distance wanderings as evidenced by recent satellite tracking data from Lesser Frigatebirds. One individual tagged in the western Indian Ocean spent the following winter north of Australia, and was last detected the next year heading east into the central Pacific Ocean, covering a distance of almost 10,000 miles!

female great frigatebird
Adult female Great Frigatebird

With most of the Hawaiian population nesting in the protected Northwestern Hawaiian Islands, Great Frigatebird populations appear to be either stable or increasing in Hawaiʻi, especially since the end of WWII. Military activity on many of the Northwestern Islands during WWII had adverse affects on all seabird populations. However, since the end of WWII, Great Frigatebirds have benefited greatly from increased land area on those islands due to land expansion by the military, and the increased amount of non-native vegetation which provided additional nesting habitat. However, on other oceanic islands outside of Hawaiʻi, most Great Frigatebird populations are in decline due to heavy persecution for food (eggs, chicks, and adults), and lack of resources to prevent hunting and poaching, as well as habitat degradation and introduced mammalian predators. The subspecies in the south Atlantic (F. m. nicolli) is nearly extinct.

The distinctive shape of this seabird, with its long and deeply forked tail, long pointed wings usually held bent at the wrist,  long straight bill, large size (up to 7.5 foot wingspan), and overall black plumage make it straightforward to identify. There is a large variation in the color of the head and chest, which is related to age and sex. Adult males are solidly glossy black overall and have an inflatable red sac on the throat, which is rarely shown except at the breeding colonies. Adult females, which are apparently disproportionately common in the Southeastern Hawaiian Islands, have a black head with a white throat and chest (pictured above), whereas juveniles have a cinnamon head (which fades to white) and a white chest. It takes this species up to six years to reach a mature adult plumage, and the pattern on the head and chest in these subadults is intermediate between the cinnamon-headed juveniles and the mature adults, usually becoming quite mottled in males. However, there are no similar looking seabirds that occur regularly in Hawaiʻi, so the identification should be straightforward.