Also known as the Boatswain Bird, the red-billed tropicbird (Phaethon aethereus) is a tropical bird, one of three closely related tropical ocean seabirds. In appearance, it has mainly white plumage with some black markings on the wings and back, a black mask and, as its common name implies, a red bill, superficially resembling a tern. It has long white tail streamers, a thinly barred white back in black, curves of a black eye stripe upward behind the eye, black primaries, and a red bill. The female is similar to the male, but less tinged with red. Most adults have tail streamers that are about two times the length of their body, with males usually being longer than females. The Galapagos species, the red-billed tropicbird is additionally found within the tropical latitudes of the eastern Pacific, the Caribbean, and within the ocean. Like a number of the opposite pelecaniformes, tropicbirds are plunge-divers, feeding on squid and fish, stream baffled. After a dive, they bob keep a copy to the surface, sitting momentarily, with their two tail feathers cocked in an upright position. They are most commonly found in North America as vagabonds along the eastern and Gulf Coasts, perhaps representing dispersing birds from Caribbean breeding locations. They are the only species of tropical birds usually seen off the west coast of the United States, and only very rare vagabonds are seen there, with most occurrences off the southern California coast. These birds are found here likely dispersing from breeding locations off the Pacific Coast of Mexico.
In the genus Phaethon, the red-billed tropicbird is basal (the earliest offshoot), the only current genus in the family Phaethontidae, the tropicbirds. It is suspected that the division between this tropical bird and the other tropical birds, the red-tailed and white-tailed tropical birds, occurred about six million years ago. This species measures 90 to 105 cm (35 to 41 in) on the average, which has the 46 to 56 cm (18 to 22 in)-long tail streamers. Without them the tropicbird measures about 48 cm (19 in). It’s a wingspan of 99 to 106 cm (39 to 42 in). In overall appearance, it’s tern-like in shape. On tropical islands, the Red-billed Tropicbird breeds, laying a single egg directly on the ground or on a cliff ledge. When not breeding, it disperses widely and occasionally wanders far, including an impressive record from Great Britain. The adult Tropicbirds are slender, largely white, 48 centimeters long, with the exception of very long central tail feathers, doubling the total length. In general, the red-billed tropicbird only calls near breeding colonies, where it joins groups of other adults, numbering 2 to 20, circling over the sea, producing loud, harsh screams of kreeeee-kreeee-kri-kri-kri-kr. The chicks will vocalize a loud and piercing shriek, either rasping or reeling if disturbed by the nest. Both parents will incubate the eggs, and upon hatching, both male and feminine help to feed and lift the young. There’s no regular migration, but the species has wandered widely outside of the breeding season, with sightings as far north as Canada or perhaps Great Britain. However, most birds, particularly adults, at all seasons, seem to remain relatively close to breeding grounds. The red-billed tropicbird was shown in error on the $50 Bermudian dollar, a bird not endemic to Bermuda, and was replaced in 2012 by the white-tailed tropicbird, the Bermuda tropicbird that can be found.