Tropicbird

Tropicbird
Scientific classification
Kingdom Information
Domain	Eukaryota
Kingdom	Animalia
Subkingdom	Bilateria
Phylum Information
Superphylum	Deuterostomia
Phylum	Chordata
Sub-phylum	Vertebrata
Infraphylum	Gnathostomata
Class Information
Superclass	Tetrapoda
Class	Aves
Sub-class	Neognathae
Infra-class	Neoaves
Order Information
Order	Phaethontiformes
Family Information
Family	Phaethontidae
Genus Information
Genus	Phaethon
Population statistics

The Tropicbirds are seabirds of the family Phaethontidae, and found in the tropical waters of the Atlantic, Pacific, and Indian oceans.

Description

Tropicbirds are similar to terns, but are larger, with a body length of about 20 inches (excluding the tail feathers), a wing span of about 37 inches, and a body weight of between 10.5 and 26.4 ounces. The water-repellent plumage is white, sharply contrasted with black eye-lines; red tails, bills, or black wing markings differentiate the species.

Characteristic are the two central tail feathers, which are sometimes longer in length than the body, and sometimes referred to as streamers. They wear out very quickly, so they are often replaced. These feathers are white in two species and bright red in the third. They play a role in the courtship, and perhaps also as balance aids in flight.

The legs are short and set at the back of the body. The feet are very small, giving the birds an awkward method of movement on land as they can only push themselves their stomachs, and then only over short distances. The beak is tall, slender and pointed; it is bright red or yellow in color.

Etymology

The modern name refers to the only to the tropical habitat of these birds, yet English-speaking sailors in particular have given tropicbirds more imaginative names. The most widely used is the name "bosunbird", referring to the sound made by a boatswain's pipe. The names "marlinspike" and "straw tail" refer to the shape and appearance of the long tail feathers, with the first name based on the tool used by sailors. They were also called "noddys", because they were easy to catch while sleeping. The genus name Phaethon derives from the son of the god Helios in Greek mythology, who was allowed for one day to pull the sun chariot across the sky.

Species

• Red-billed tropicbird, Phaethon aethereus
• Red-tailed tropicbird, Phaethon rubricauda
• White-tailed tropicbird, Phaethon lepturus

Previously, tropicbirds were classified among the Pelecaniformes, in part due to similarities with the structure of the feet and lack of a brood patch. Questioning this placement would lead to research under Sibley and Ahlquist (1990), and later by Hedges and Sibley (1994), using DNA hybridization-based reconstructions. Yet at the time, the tropicbirds still remained within Pelecaniformes until the early 2000s, when recent research has shown that the tropicbirds and the prehistoric family Prophaethontidae were not related to any of the previous orders, so they were separated in the new order of the Phaethontiformes.

Diet

Tropicbirds hunt fish and cephalopods, and usually from a dive into the water from a height of 75 feet or more, capturing prey at or just below the surface. Particularly common are flying fish and small squid, which can be taken in flight while barely skimming the surface.

Breeding

Tropic birds become sexually mature at the age of 3–4 years. They breed on tropical islands where they form small colonies with little social interaction. The breeding grounds can be found on inaccessible cliffs or on on sandy shores, where nests can be hidden under vegetation. On Christmas Island, tropic birds even breed in trees in the mountainous interior of the island. Regionally, the breeding season is very different, with breeding on some islands taking place throughout the year, and other places limited to the spring and summer months.

Breeding is preceded by a spectacular courtship flight, involving climbing to altitude and diving, with both birds touching wingtips and tail feathers. Afterwards, the couple lands at a suitable nesting site and usually copulates immediately after landing. If the ground permits, a small hollow is dug for the egg. If suitable nesting sites are scarce, fighting for such places can occur, with opponents using their beaks to hack on the heads of each other. If an opponent is successful, the others who had previously nested on the spot must give up their egg or chick. Due to the fighting in some places only 30% of the breeds are successful. Tropicbirds also use this aggressiveness against other species: they sometimes successfully displace petrels and take over their nesting sites.

A single egg is laid. The eggs of tropic birds are extremely variable; there are white, gray, brown or red, some monochrome, others are spotted. The egg is incubated for 40 to 46 days by both partners. The chick is initially fed with pre-digested food that the parent birds regurgitates into the chick's throat. Over time the chick is left alone more often, with the intervals between feedings increasing, and at about 70 to 90 days of age it makes its first flight and does not return to the nesting site.

The maximum age of tropic birds is unknown, but in any case exceeds sixteen years.

Threats

Tropicbirds have always been used by the inhabitants of tropical islands. Polynesians have used the feathers as adornments, and subsisted on its eggs and meat. Even today, nests are looted in many places. A much bigger threat to tropicbirds is introduced predators; the islands on which they breed had no known natural predators prior to man's arrival; once introduced, feral cats and rats took their toll. On Christmas Island the current problem is the introduced yellow crazy ant (Anoplolepis gracilipes). The islands on which these birds breed are often so remote that there were no mammals to fear. Later, sailors exposed cats and rats there, devastating the local fauna. On such islands, the breeding succeed only on inaccessible cliffs. A study on the Kure Atoll has revealed that in some years 100% of the eggs and chicks have been predated on by rats.

Evolutionary claims

According to the theory of evolution, tropicbirds are considered old, with the genera Lithoptila and Prophaethon appearing in the Paleocene and Eocene epochs, and the genus Heliadornis, considered the first true tropicbird, in the Miocene.

Creation science holds that the tropicbirds were created by an act of God during the creation week as described in chapter 1 of Genesis. In support of divine creation it should be noted that all fossil remains indicate the sudden appearance of all animals fully-formed, without transitional forms present; in the tropicbird's example one would need fossil evidence showing the gradual reduction in size of the legs and feet. Very little fossil evidence of supposed tropicbird ancestors has been found to date, and in the case of Heliadornis, an identification and assumption was based upon a single humerus bone found in Belgium, and three bones found in Maryland, none of which were leg bones.