The Red-tailed Tropicbird (Phaethon rubricauda) is the most pelagic of the three species of tropicbirds. It ranges throughout the tropical Pacific and Indian oceans, nesting on islands. Young birds fledge alone, possibly with some postfledging parental care (Ainley et al. 1986), and most do not return to land for at least two years. During that time they wander, usually as single birds, well away from the sight of most observers. Most individuals return to breed at an age of 2–7 years. Although breeding at an age as young as 9 months, in a “near-adult like plumage,” has been reported (Schreiber and Schreiber 1993), we question this and wonder if the bird was older than suspected when banded the year before (see below). The majority of birds return by the age of 4 years, but those that reportedly return to breeding islands at 2 years of age (presumably in second basic plumage) are in almost full adult plumage (Schreiber and Schreiber 1993), and little is known about the species’ definitive molts and plumages. This uncertainty is compounded by year-round breeding in many populations, meaning that molts and plumes may not follow regular, season-based cycles at the population level. Individuals may undergo prebasic molts at intervals of less than one year (e.g., if a breeding attempt fails) or more than one year (e.g., if a breeding attempt was prolonged or skipped).