Phaethon aethereus
Silhouette: Paul Baker (photo), John E. McCormack, Michael G. Harvey, Brant C. Faircloth, Nicholas G. Crawford, Travis C. Glenn, Robb T. Brumfield & T. Michael Keesey · PhyloPic
In 3 days ~60% in a week ~90%
The red-billed tropicbird (Phaethon aethereus) is a tropicbird, one of three closely related species of seabird of tropical oceans. Superficially resembling a tern in appearance, it has mostly white plumage with some black markings on the wings and back, a black mask and, as its common name suggests, a red bill. Most adults have tail streamers that are about two times their body length, with those in males being generally longer than those in females. The red-billed tropicbird itself has three subspecies recognized, including the nominate. The subspecies mesonauta is distinguished from the nominate by the rosy tinge of its fresh plumage, and the subspecies indicus can be differentiated by its smaller size, more restricted mask, and more orange bill. This species ranges across the tropical Atlantic, eastern Pacific, and Indian Oceans. The nominate is found in the southern Atlantic Ocean, the subspecies indicus in the waters off of the Middle East and in the Indian Ocean, and the subspecies mesonauta in the eastern portions of both the Atlantic and the Pacific Oceans and in the Caribbean. It was one of the many species described by Carl Linnaeus in his 1758 10th edition of Systema Naturae.
Nesting takes place in loose colonies, as they nest a scrape found on a cliff face that is easy to take off from. A single egg is laid and is incubated by both sexes for about six weeks. Whether the egg hatches or not can be influenced by pollution and weather, although the latter has a minimal effect on whether a chick fledges or not. After a chick fledges, the parents will usually stop visiting the nest and the chick will leave. Birds of all ages feed on fish and squid, catching them by diving from the air into the water. However, the red-billed tropicbird sometimes follows surface-feeding predators. The predators will drive the prey to the surface, which are then seized by the tropicbird.
In some areas, introduced black and brown rats raid nests for eggs and young. Cats also threaten the red-billed tropicbird. This bird is considered to be a least-concern species according to the International Union for Conservation of Nature (IUCN), though populations are thought to be declining. In some places, such as Brazil and Mexico, this bird is considered to be threatened. Wikipedia →
| # | Park | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Galápagos Islands | 🇪🇨 Ecuador | |
| 2 | Machalilla National Park | 🇪🇨 Ecuador | |
| 3 | Main Ridge Forest Reserve | 🇹🇹 Trinidad and Tobago | |
| 4 | Bastimentos Island National Marine Park | 🇵🇦 Panama | |
| 5 | Cabo Pulmo National Park | 🇲🇽 Mexico | |
| 6 | La Amistad International Park (Panama) | 🇵🇦 Panama | |
| 7 | Bahía de Loreto National Park | 🇲🇽 Mexico | |
| 8 | Manuel Antonio National Park | 🇨🇷 Costa Rica |
| # | City | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Dakar | 🇸🇳 Senegal |
No species of the same family or order lives in Machalilla National Park, so these are its closest relatives here: other birds.
Possible
About 30% of wildlife watchers report a Red-billed Tropicbird sighting in Machalilla National Park on a given day, based on 242 verified sightings from GBIF citizen-science data from 2019 to 2026. It is the 33rd most-seen of the 248 birds we can rate there. Over three days the chance rises to about 60%, and over a week to about 90%, if each day is a fresh chance.
June–July and November
In those months about 40% of wildlife watchers report a Red-billed Tropicbird in Machalilla National Park on a given day, against about 10% in February, the lowest month. Those are among Machalilla National Park's driest months, with about 10 mm of rain a month against 140 mm in February.
Between 2 and 5 pm
Across all the parks we cover, that three-hour window holds the most Red-billed Tropicbird sightings with a recorded time, and about 9 in 10 of them come between 6 am and 6 pm: it is a daytime animal.
Among the best
Of the 8 parks where we can rate Red-billed Tropicbird sightings, Machalilla National Park ranks 2nd at about 30%, level with the leaders once rounded. The best odds are in Galápagos Islands (Ecuador, about 30%).
GBIF citizen-science records
It is estimated from how often the Red-billed Tropicbird is recorded against all the birds logged in Machalilla National Park (242 verified sightings from 2019 to 2026), calibrated against known sighting rates. Figures are rounded to the nearest 10% because citizen-science data supports honest approximations, not decimals, and months with records from fewer than five people show "—". How it works.
