Frigatebird Facts | Galapagos Islands Wildlife Guide
Despite the sinister look of its elongated, angular beak, this huge, black seabird with a wingspan of almost 8 feet is quite elegant and streamlined. With the largest wingspan to weight ratio of any bird in the world, it is no wonder these birds are fantastic fliers.
Two species, the magnificent frigatebird and the great frigatebird, inhabit the Galapagos. Colonies exist on many islands, but the consistently energetic, magnificent frigatebird colony on North Seymour Island offers the best opportunity for viewing. Because great frigatebirds typically travel farther out on the ocean, they can usually be seen on the outer islands.
It is challenging to differentiate between these two completely black, males species. The magnificent frigatebird, which measures 3.6 feet long, is only about 2 inches longer than the great frigatebird—a virtually imperceptible difference from the field. In addition, the male magnificent’s black plumage sparkle with a purplish sheen, while the great frigate’s shimmers with a greenish shade. Both of these subtle differences are only apparent to the most experienced eyes.
Fortunately, it is easier to differentiate between females. Magnificent females have a blue eye-ring and white underparts adorned with a black throat while great females have a reddish eye-ring and entirely white underparts, including the throat. Identifying the females allows you to assume their mates are the same species. Both juveniles have white underparts and white heads.
Like many seabirds here, the frigatebird puts on a remarkable courtship display. The females visibly search out and select mates by taking flight over the rookery to examine males, who band together in groups. When a female flies low circles overhead, males respond in kind by inflating the scarlet gular pouches that dangle below their necks. After approximately 20 minutes, these heart-shaped, football-sized balloons reach full inflation. Typically, the male displays it heavenward in an effort to entice to attract females as they pass overhead. He also makes loud drumming and clicking sounds and vibrates his wings rapidly to further entice females. Once paired, the couple begins building nests. Frigates are known for stealing twigs from nearby nests so while the male searches for twigs, the female remains at the nest site to protect it from thieves.