The white-tailed tropicbird (Phaethon lepturus) is a species of tropicbird. It is the smallest of three closely related seabirds of the tropical oceans and smallest member of the order Phaethontiformes. It is found in the tropical Atlantic, western Pacific and Indian Oceans. It also breeds on some Caribbean islands, and a few pairs have started nesting recently on Little Tobago, joining the red-billed tropicbird colony. In addition to the tropical Atlantic, it nests as far north as Bermuda, where it is locally called a "longtail".
The White-tailed Tropicbird occurs in tropical and subtropical oceans of the world (Oberle 2018, Raffaele and others 1998). It is a locally common breeding resident in the West Indies, especially from March to June (Raffaele and others 1998), although birds actually start arriving in late December and are already in breeding mode by January. It has declined dramatically in recent centuries on Puerto Rico, as it once nested on cliffs of the southwestern and northern coasts of the mainland and is now restricted mostly to the northwestern coast as well as Culebra and associated cays (Schaffner 1991), Caja de Muerto, and Mona and Monito islands (Biaggi 1997, Kepler 1978, Oberle 2018). However, it is also present near Desecheo (Biaggi 1997), and on Vieques it is considered rare in spring and summer, and extremely rare in winter (Gemmill 2015). It is regularly seen around the cliffs between the municipalities of Isabela and Barceloneta, especially near Guajataca (Oberle 2018). It usually occurs far out at sea, except when visiting sea cliffs for nesting (Raffaele and others 1998). The atlas fieldwork yielded a total of 45 records within 28 hexagons or 6 percent of the 479 total hexagons (see map). Of the 28 hexagons where this species was found, breeding met the atlas definition of confirmed in 57 percent (16) of the hexagons, probable in 7 percent (2), and possible in 11 percent (3), while the species was observed in 25 percent (7) of the hexagons but without evidence of breeding (see map).White-tailed Tropicbird distribution. The map shows the highest breeding code by hexagon and overlaying the ecological life zones in Puerto Rico. Note: percentages may not total 100 due to rounding. 129White-tailed Tropicbird/Chirre Coliblanco
Previously published reports indicate that the White-tailed Tropicbird breeds primarily from March to July (Raffaele and others 1998). This species nesting is now mostly restricted to rocky crevices and bare ledges on sea cliffs or talus slopes (Oberle 2018, Raffaele and others 1998, Schaffner 1991). Atlas results show that this species breeds from February to July with the most breeding activity during the months of March and April (see chart). The breeding activity peaks in April, and it mostly takes place within the subtropical dry forest life zone (see chart). Results show that this species breeds in coastal areas mostly within the subtropical dry forest life zone (76 percent of the hexagons) (see table) but also within the subtropical moist forest life zone (24 percent of the hexagons) (see table and map).
The current global population trend of the White-tailed Tropicbird is suspected to be in decline due to predation by invasive species (BirdLife International 2018). Nonetheless, it is currently listed as a species of least concern by the IUCN (BirdLife International 2018). Locally, this species is not listed in any of the threatened categories of PRDNER and USFWS. In Puerto Rico, the White-tailed Tropicbird has a protected habitat in land of 18 percent or 89 km2 of the total area covered by the hexagons where evidence of breeding was found for this species (503 km2).