There are 2 species of frigatebird in the Galapagos, the Magnificent Frigatebird and the slightly smaller Great Frigatebird.
They closely resemble one another, with black plumage, long, forked tails and tapering wings. Males have a bright red gular sac while females have white breasts. They are unable to swim and cannot walk well, so spend much of their time in the air and can stay airborne for over a week. They feed on the wing, using their long, hooked beaks to snatch prey from the surface of the water or in the air. They supplement their diet by harassing other seabirds such as blue-footed boobies, forcing them to disgorge their food.
They reach maturity at 4 years and breed throughout the year. Males display by inflating their gular sac, calling and holding their long wings outstretched, vibrating them. Frigatebirds nest in colonies, building nests in trees or on the ground. The female lays a single egg and both birds take turns feeding the chick for the first 3 months, after which time the mother takes sole charge of rearing for the next 8 months. The length of the rearing process means that birds cannot breed every year.
Both the Magnificent and Great Frigatebirds can be found nesting on Espanola, San Cristobal, Floreana, North Seymour, Isabela and Genovesa. There are also colonies on Wolf, Darwin, Los Hermanas and Tortuga.