A Field Guide to the Birds of Hawaii and the Tropical Pacific. Pan-American Journal of Aquatic Sciences 11:87-92. minor nicolli, Suliformes: Fregatidae) at Trindade Island, Brazil. Observations on endangered frigatebirds ( Fregata ariel trinitatis and F. A Guide to the Birds of Mexico and Northern Central America. Island Heritage Publishing, Waipahu, Hawaii. eBird: An online database of bird distribution and abundance. Christmas’s belly is always white (at least mostly white), whereas subadult Greats of both sexes darken on the belly while retaining an all- or mostly white chest.īirdLife International. Male Christmas is black with a white belly and male Great is essentially all-black. Christmas’s belly is always white (at least mostly white), whereas subadult Greats of both sexes darken on the belly while retaining an all- or mostly white chest. As the sexes differentiate, Christmas and Great Frigatebirds become easier to identify based on the color of the belly. Subadult Females: Usually distinguishable. Until Great’s belly begins to darken, the most consistent difference is that Christmas’s white underparts extend into its armpits. Most confusing are the juvenile and other immature plumages, which vary widely and can be essentially identical in color and pattern. Immatures: Usually distinguishable, but complicated. Female Christmas has a full black hood and white belly, whereas female Great has a pale throat and black belly. Male Christmas is black with a white belly and male Great is essentially all-black.Īdult Females: Distinctive. Adult plumages of the two species are distinctive, but immatures are readily confused.Īdult Males: Distinctive. Christmas and Great Frigatebirds occur together throughout Indonesia, the Timor, Banda, and Arafura Seas, and in nearby portions of the eastern Indian and western Pacific Oceans. Female Greats often have pinkish bills, while female Magnificent’s bill is generally pale grayish or horn-colored.Ĭf. Female Magnificents begin to darken on the throat, whereas female Greats do not, so this may allow for positive identification of Magnificent in some cases. Subadult Females: Sometimes distinguishable, but complicated. As they age, the differences become less pronounced, such that second-cycle immatures are mostly similar both within and between the two species. However, immature Greats are polymorphic and some portion of them have an all-white head like Magnificent-in which case there may be no reliable difference. Juveniles and older immatures are often distinguishable, as most juvenile Greats have a tawny (or buffy or orange or reddish) hood, which they retain at least in part into the second year. Immatures: Often distinctive, but complex and sometimes indistinguishable. Bill color differs accordingly, but to a lesser extent. In the eastern Pacific populations, which are most likely to occur together, the females also differ in their eyerings: bluish on Magnificent, red on Great. Magnificent has a full blackish hood, whereas Great has a pale throat. If the lighting is right to catch reflections, Great often shows a strong green or purple gloss on the back feathers, whereas Magnificent is usually duller and purplish or coppery.Īdult Females: Distinctive. If the upperparts are visible, the presence of a distinct alar bar on the wings would suggest Great. They likely occur together somewhat more often in the eastern Pacific, but would be difficult to recognize due to their confusing similarities and the difficulty of tracking the various distinctions that apply to certain plumages.Īdult Males: Effectively indistinguishable under most field conditions. Magnificent and Great Frigatebirds occur together regularly in the Galápagos and Ecuadorian waters, around remote Mexican islands, and to a very limited extent in Brazilian waters.
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