This bird is considered to be a least-concern species according to the International Union for Conservation of Nature (IUCN), though it is adversely affected by human contact.

[4] The bird was also illustrated in a hand-coloured plate engraved by François-Nicolas Martinet in the Planches Enluminées D'Histoire Naturelle which was produced under the supervision of Edme-Louis Daubenton to accompany Buffon's text.

[6] The genus name is derived from Ancient Greek phaethon, "sun", while the species epithet comes from the Latin words ruber "red" and cauda "tail".

[7] English ornithologist John Latham wrote about the red-tailed tropicbird in 1785 in his General Synopsis of Birds, recording it as common in Mauritius and the South Pacific.

It was left to German naturalist Johann Friedrich Gmelin to describe the species, which he did as Phaeton phoenicuros and P. melanorhynchos respectively in the 13th edition of Systema Naturae in 1788.

[11] The British naturalist Walter Rothschild reviewed the described names and specimens in 1900 and concluded that the original use of P. erubescens was a nomen nudum.

He concluded that the populations of Lord Howe, Norfolk and Kermadec Islands belonged to a distinct subspecies which he named P. rubicauda erubescens, due to their larger overall size, more robust bill and prominent reddish tinge to their plumage.

[15] Its closest relative is the white-tailed tropicbird (P. lepturus), the split between their ancestors taking place about four million years ago.

The two long tail feathers are orange or red with white bases for around a tenth of their length,[21] and can be hard to see when the bird is flying.

[21] Juvenile birds have a glossy white forehead, chin, throat and underparts,[20] and prominent black barring and scaling on their crown, nape, mantle, back, rump and upper wing coverts.

[20] In Australian waters the red-tailed tropicbird could be confused with the silver gull (Chroicocephalus novaehollandiae) or various tern species, though it is larger and heavier-set, with a wedge-shaped tail.

Evidence suggests birds in the Indian Ocean follow prevailing winds westwards, young individuals banded in Sumatra and Sugarloaf Rock, Western Australia, being recovered at Mauritius and Réunion respectively.

[25] Banding on Kure Atoll suggests birds in the North Pacific disperse in an easterly direction, following prevailing winds there.

[38] It nests in loose colonies,[39] on offshore islands and stacks, rocky cliffs, coral atolls and cays.

The nest is often located within one metre (3.3 ft) of the edge of the shrub (or other shaded area) to minimise walking distance.

[41] The species is territorial to a degree, aggressively defending the nest site and pecking radius around it, commencing around three months before breeding.

[43] In the leadup to breeding, males initiate an aerial courtship display of flying in large circles, alternating between gliding, short periods of rapid wing-beating, and low flight within a few metres of the water, while making sharp cackling calls.

On islands near the equator, laying usually occurs from June to November, the majority of chicks fledging around January to February.

[22] Born helpless and unable to move around (nidicolous and semi-altricial), the chicks are initially blind, opening their eyes after 2–3 days.

[45] When diving, it remains briefly submerged—one study on Christmas Island came up with an average time of 26.6 seconds—generally swallowing its prey before surfacing.

[46] Squid and flying fish make up a large portion of this bird's diet, along with some crustaceans, depending on location.

Fish recorded include the mirrorwing flyingfish (Hirundichthys speculiger) and spotfin flyingfish (Cheilopogon furcatus) and several other unidentified species of the flying fish family Exocoetidae, the pompano dolphinfish (Coryphaena equiselis) and common dolphinfish (C. hippurus), needlefish including the houndfish (Tylosurus crocodilus), and unidentified members of Hemiramphidae, Scombridae, and Carangidae.

[49] The red-tailed tropicbird has also been recorded eating porcupinefish (Diodontidae), although adults have been troubled when the victim fish inflates resulting in it being urgently regurgitated.

[51] English naturalist Andrew Bloxam reported that the feathers were valued in Hawaii, where the locals would pull them off the birds as they nested.

[52] The red-tailed tropicbird is classified as a least-concern species according to the IUCN on account of its large range of up to 20 thousand square kilometres (7,700 sq mi).

[23] Within Australia, it is classified as near threatened, due to unexpected declines in some populations, the impact of humans, and the yellow crazy ant overrunning Christmas Island.

[56] Predators recorded in Western Australia include large raptors such as the white-bellied sea eagle (Haliaeetus leucogaster) and the eastern osprey (Pandion cristatus); while silver gulls, and crows and ravens (Corvus spp.)

[26] Yellow crazy ants were discovered on Johnston Atoll in the north Pacific Ocean in 2010, hordes of which overrun nesting areas and can blind victims with their spray.

There appeared to be no impact on survival during the study period, although young birds from downwind of the plant were less likely to return there than those upwind of the plant—possibly due to the more intact vegetation at the latter site.

Their study includes taking DNA samples, banding new chicks and fitting birds with satellite trackers, in a bit to find out more about their movements.