The Christmas frigatebird is a very large, mostly black seabird with a glossy green sheen to feathers of the head and back . Females are larger than males ; they have a white breast and belly, a narrow white collar around the lower neck and a whitish bar across the upperwing . Males are dark all over apart from a white patch on the lower abdomen. They have a red gular pouch, which becomes more vibrant in the breeding season and is inflated during mating displays . Juveniles have more mottled feathers on their upper-parts , a pale fawn head, white throat and a russet necklace . They take around four years to gain adult plumage .
Males Christmas frigatebirds begin their mating displays in late December , inflating their scarlet throat pouches during courtship . Egg laying occurs between March and May and nests are positioned high in tall forest trees . A single egg is laid and both parents take it in turns during the 50 to 54 day incubation period; fledglings can remain dependant on their parents for six to seven months after their first flight .