The Magnificent Frigatebird (Fregata magnificens) is a migratory bird distributed throughout North and South America. The species is sexually dimorphic and dichromatic. Individuals weigh between 1 kg and 1.9 kg with females typically 11% to 23% heavier than males. Male plumage is black with purple glossing on the head and green glossing on the neck. Additionally, males have a bright red gular sac that is used to attract females. Female plumage is brownish black with a white patch on the breast and upper belly. Magnificent frigatebirds are 89 cm to 114 cm in length with an average wingspan between 217cm and 224 cm (Diamond and Schreiber, 2002).
Magnificent frigatebirds belong to a grouping of birds known as the Pelicaniforms. Pelicaniformes have a totipalmate foot in which all digits are connected by webbing. The group is also characterized by a gular or throat pouch (Feduccia, 1996).
During the non-breeding season, the magnificent frigatebird is found as far north as Alaska and as far east as the western coasts of Europe and Africa. The breeding range of the Magnificent frigatebird is throughout the Caribbean islands and the tropical areas of the east and west coasts of Central and South America. Breeding occurs in mangroves on coral reefs or in deciduous trees and bushes on dry islands. The magnificent frigatebird uses a male lek mating system. Males form groups of six to 30 individuals and each male selects a nesting spot. Females fly over the grouping of males and choose a mate. The nest is built upon the chosen display site of the male (Diamond and Schreiber, 2002).
Clutch size of the magnificent frigatebird is one egg and the incubation period lasts between 53 and 61 days. Both parents participate in nest defense and incubation of the egg. Females feed young for 10 to 16 months but males help feed the young for only three months. Three months after the young has hatched, males abandon their mates and the colony to molt. Males return to the colony the next breeding season to mate again, usually with another mate. Therefore, males are able to mate annually. Females only are able to mate every other year because they stay with their young for up 16 months (Diamond and Schreiber, 2002).
The diet of the magnificent frigatebird consists mostly of flying fish and squid. However, other prey items include young turtles, crabs, jellyfish, plankton, and young of other seabirds. The magnificent frigatebird is a glider and has a forked tail used to maneuver in the air. The species has not been observed swimming or diving and cannot walk bipedally. Individuals are usually perched when not gliding (Diamond and Schreiber, 2002).
The magnificent frigatebird defends its nest, although no other territoriality has been observed. Aggressive behavior typically occurs over food items and individuals often steal food from conspecifics or members of other species. Additionally, females will force other individuals, including young, from perches.
Additional Information on the Skull
Click on the thumbnails below for labeled images of the skull in standard anatomical views.
Baumel, J. J., A. S. King, J. E. Breazile, H. E. Evans, and J. C. Vanden Berge (eds.). 1993. Handbook of Avian Anatomy: Nomina Anatomica Avium, Second Edition. Publication of the Nuttall Ornithological Club, number 23. Nuttall Ornithological Club, Cambridge, Massachusetts, 779 pp.
Diamond, A. W., and E. A. Schreiber. 2002. Magnificent frigatebird: Fregata magnificens. Birds of North America 601:1-23.
Feduccia, A. 1996. Origin and Evolution of Birds. Yale University Press, New Haven, CT. pp 420.
Fregata magnificens on the USGS Patuxent Bird Indentification InfoCenter.