Red-billed Wren, a tropical bird, also known as the Short-tailed Wren or Red-billed Tropical Bird.

Detailed introduction

The Red-billed Wren (scientific name: *Phaethon aethereus*), also known as the Tropical Wren or Short-tailed Wren, is a medium-sized seabird belonging to the family Phaethidae in the order Pelecaniformes. Except during the breeding season when it comes ashore to lay eggs and raise its young, it spends the rest of its time flying over the ocean. Sometimes it will follow fishing boats for extended periods, resting on the masts. It is mostly found alone or in pairs, feeding primarily on flying fish and squid, but also on crustaceans. It is distributed throughout the tropical oceans, including the Indian Ocean, Pacific Ocean, Atlantic Ocean, and other tropical and subtropical regions, as well as the Xisha Islands on the Chinese mainland, where it often inhabits the cliffs of marine islands.

Red-billed Swallowtail. Body length approximately 46 cm (excluding tail feathers), total length approximately 105 cm, wingspan 99-106 cm, weight 600-840 g. Entirely white, with long red tail feathers and a vermilion bill, making it a very beautiful seabird. The front half of the bill is slightly curved, with serrated edges, and is 55-60 mm long, for hunting fish. It has long wings, short legs, and small, fully webbed feet. The central tail feathers are elongated, white, and about one-third the length of the body; there is a black spot on the lores, extending behind the eye to the neck, forming a broad eye stripe; the back has black transverse bars; the primary flight feathers are black with broad white edges on the inner webs. It has fully webbed feet, with all four toes pointing forward; a gular pouch of varying development is often present under the bill.

Adult birds are characterized by horizontal bars on their upperparts and a white ribbon on their tail. Juveniles/subadults differ from the White-tailed Swallowtail and Red-tailed Swallowtail in having dense, fine horizontal bars on their upperparts and a characteristic broad eye stripe extending to the nape to form a ring. Iris is dark; bill is red; legs are yellowish, and webbed feet are black.

Except during the breeding season when it comes ashore to lay eggs and raise its young, the Red-billed Pitta spends the rest of its time soaring high above the ocean. It is a strong flier, reaching speeds of up to 44 kilometers per hour (27 miles per hour) over the sea, and maintaining a height of at least 30 meters (100 feet) above the surface while cruising. It cannot stand upright and is not adept at walking; it requires an unobstructed takeoff point from land. Conversely, it takes little effort to take off from the sea. Its feathers are waterproof, allowing it to float on water. It is quite elegant. When feeding, it first hovers in the air, flaps its wings, and then plunges into the water with its wings half-closed, a hunting motion similar to that of a booby. Sometimes it follows fishing boats for extended periods, resting on the masts. It is mostly solitary or in pairs, feeding mainly on flying fish and squid, but also on crustaceans. It often carries food home in its beak to feed its young, emitting loud screeching calls when flying over its nesting area and circling boats.

Distributed in the tropical and subtropical parts of the Pacific and Indian Oceans, from Oceania in the south to Japan, Taiwan, Anguilla, Antigua and Barbuda, the Bahamas, Barbados, Bonaire, Saint Eustachians and Saba, Brazil, Cape Verde, the Cayman Islands, Chile, China, Colombia, Cuba, Curaçao, Djibouti, Dominica, the Dominican Republic, Ecuador (Galapagos Islands), Egypt, El Salvador, Eritrea, French Guiana, Grenada, Guadeloupe, Guinea, Guinea-Bissau, Haiti, the Islamic Republic of Iran, the Maldives, Mauritania, Mexico, Montserrat, Oman, Pakistan, Panama, Peru, Portugal, Puerto Rico, Qatar, Saint Helena, Ascension Island, Tristan da Cunha, Saint Kitts and Nevis, Saint Lucia, and Saint Martin (French territory). They live mainly on the cliffs of oceanic islands in Saint Vincent and the Grenadines, Saudi Arabia, Senegal, Saint Martin (Netherlands), Somalia, Trinidad and Tobago, Turks and Caicos Islands, United Arab Emirates, Bolivarian Republic of Venezuela, Virgin Islands, Yemen, and other places.

Migratory birds: Angola, Bermuda, Costa Rica, French Polynesia, Gabon, Gambia, India, Israel, Jamaica, Jordan, Kuwait, Madagascar, Malaysia, Mauritania, Myanmar, Netherlands, Seychelles, South Africa, Spain (Canary Islands), Sri Lanka, Sudan, United Kingdom, United States (Hawaii), Vietnam.

Origin uncertain: Bahrain, Belize, Benin, Cameroon, Democratic Republic of Congo, Ivory Coast, Equatorial Guinea, Ghana, Guatemala, Guyana, Honduras, Iraq, Liberia, Nicaragua, Nigeria, São Tomé and Príncipe, Suriname, Togo, Western Sahara.

This tropical bird undergoes a molt once a year, employing a complex basic strategy. This molt is completed before courtship, lasting 19 to 29 weeks, with most birds completing it within 24 weeks. The chicks then grow adult feathers at two to three years of age.

Red-billed pheasants typically call only near their breeding colonies. They join flocks of 2 to 20 adults, circling over the sea and emitting a loud, piercing call. If startled in the nest, the chicks will emit a loud, sharp call, which can be quite shrill and last for some time.

Red-billed lorikeets are monogamous and typically nest on isolated cliff faces, forming loose colonies. They use simple scuffing nests located in places where they can easily take flight. The age of first breeding is usually five years, but this age is variable; a three-year-old tropical bird has been observed breeding. The breeding season varies by region, sometimes year-round and sometimes seasonal. For example, on islands in the California Current, breeding begins in November or December, while in the Galapagos Islands it occurs year-round. Breeding is influenced by food availability; increased food generally leads to increased breeding. An individual's breeding cycle is nine to twelve months. A breeding bird typically returns to the mate and nesting location from the previous breeding cycle.

Courtship and pairing typically last three to five weeks, during which time the bird displays courtship displays to potential mates. These displays involve gliding through the air and intermittently rapid wing flapping. In one display, a pair of birds glide together for 100–300 meters (330–980 feet), with one bird about 30 cm (12 inches) above the other. The bird above bends its wings downwards, while the bird below raises its wings upwards, bringing them almost to touch. The two birds then descend to about 6 meters (20 feet) above the sea surface before separating.

Fights sometimes break out between pairs of birds vying for nesting locations until the original nester asserts ownership. Red-billed jays are aggressive in their nesting positions, fighting with other birds and driving away species such as gulls, petrels, and white-tailed pheasants. They have even been recorded taking over nests and raising chicks if they fail to destroy white-tailed pheasant eggs. In Hawaii, vagrant red-billed pheasants are believed to be linked to the loss of eggs from red-tailed pheasant nests.

This tropical bird typically lays a single white to pale purple egg with reddish-brown spots. The egg usually measures 45 by 60 mm (1.8 by 2.4 inches) and weighs about 67 grams (2.4 ounces), roughly 10% of the adult female's body weight. Both parents incubate the egg for 42 to 46 days. If the egg does not survive the first few days in the nest, the female will usually lay a replacement egg. The chicks typically leave the nest within about 10 to 15 weeks of hatching, although most leave after about 80 to 90 days. The maximum weight of a chick is usually about 725 grams (1.6 pounds), but in years with higher than average temperatures, this can drop to about 600 grams (1.3 pounds).

Newborn chicks are helpless and immobile (nesting and semi-alteric), remaining at home until they are 3 to 5 days old and can regulate their own body temperature, before being closely cared for by their parents. The chicks grow their first feathers—shoulder feathers—at 13 to 15 days, followed by primary flight feathers at 24 to 27 days, and tail feathers at 30 to 35 days, resulting in a greyish downy plumage. This down will shed within approximately 40 to 50 days. Young birds lack the tail ribbon. They resemble adults, with mostly white heads. The stripe above the eyes usually connects at the nape of the neck. The tail feathers typically have black tips or sub-tips and lack the tail ribbon characteristic of adults. Occasionally, young birds may have black markings on their flanks and undertail coverts. They are fully grown within 55 days. Between days 30 and 60, the parents provide more care; this may be related to the chicks' higher food requirements during this period. Semi-digested food is regurgitated and then fed to the young birds, while older birds are fed solid food. Normal parent-child care continues until about 70 days of age, after which parental care decreases rapidly. Chicks cease care after leaving the nest; only about one-seventh of chicks are still being fed after 80 days, and after about 90 days, almost no chicks are visited. Chicks leave the nest after leaving it, with a few remaining for about 100 days. Adult birds feed their young for 67-91 days.

The Red-billed Pitta can be distinguished from other tropical birds by its red beak and white tail ribbon. The slightly smaller Red-tailed Tropical has a red rather than white tail ribbon, while the White-tailed Tropical can be distinguished by its smaller size, black stripes on its upper wing coverts, and yellow-orange beak. Juvenile Red-billed Tropical birds have more horizontal bars on their upper wing compared to juveniles of other species. In flight, the Orange-billed Crested Tern can be confused with adult Red-billed Tropical birds, but can be distinguished by the former's less direct flight pattern and lack of a tail ribbon.

This tropical bird undergoes a molt annually, employing a complex basic strategy. This molt is completed before courtship, lasting 19 to 29 weeks, with most birds completing it within 24 weeks. The chicks develop adult plumage at two to three years of age. They reach sexual maturity at 2-5 years of age and return to their breeding grounds to nest and court.