Royal terns are striking seabirds found along coastlines, estuaries, and beaches in many parts of the world. Their distinctive orange-red bill makes them easy to identify. Understanding where Royal terns live and their range can help us better protect these birds and their habitats.
What are Royal terns?
Royal terns (Thalasseus maximus) are large seabirds in the family Laridae, which includes gulls, terns, and skimmers. Adults have pale gray upperparts, white underparts, a black crown, and bright orange-red bills. Their long, pointed wings and deeply forked tails give Royal terns a graceful appearance in flight.
Royal terns measure 36–43 cm (14–17 in) long with a wingspan around 95–105 cm (37–41 in). They weigh approximately 275–475 g (9.7–16.8 oz). Males and females have similar plumage. Juveniles are paler overall with a black bill.
These seabirds are found along coastlines in tropical and subtropical regions worldwide. They nest in dense colonies on sandbars, barrier islands, shell rakes, and coral islands. Royal terns dive from the air to catch fish and other prey, typically within a few kilometers of their breeding sites.
Where do Royal terns live?
Royal terns have an extensive range across the tropical and subtropical latitudes of the Atlantic, Pacific, and Indian Oceans. Their breeding and wintering ranges include:
North America
In North America, Royal terns nest along the Atlantic Coast from North Carolina to Florida, around the Gulf of Mexico, and down into the Caribbean. Important breeding sites include Cape Lookout National Seashore, Cape Romain National Wildlife Refuge, and colonies off the Florida Keys.
After breeding, most Royal terns from eastern North America migrate down the Atlantic coast of Central and South America. Some move west across the Gulf of Mexico.
Central and South America
Royal terns are found year-round along both coasts of Central America and down the west coast of South America to northern Peru. Major wintering sites include Panama Bay and the Gulf of Guayaquil in Ecuador.
On the Atlantic coast, they nest as far south as Argentina. Breeding colonies occur in Brazil, at Lagoa do Peixe National Park for example. Other important sites are along the Caribbean coast and offshore islands.
Europe and Africa
In Europe, small numbers of Royal terns breed sporadically along the French Atlantic and Mediterranean coasts. Several colonies are found around the Cape Verde Islands off West Africa.
Along the West African coast, Royal terns nest from Mauritania to Gabon. Major breeding sites include Arquipelago dos Bijagós in Guinea-Bissau, Banc d’Arguin National Park in Mauritania, and islands off Gabon.
On the southeast Atlantic coast, they nest from Namibia to South Africa, including at De Hoop Nature Reserve and St Lucia Estuary. Robben Island near Cape Town supports up to 2,500 breeding pairs.
Indian Ocean and Asia
In the Indian Ocean, important breeding sites for Royal terns occur on islands off Madagascar, the Seychelles, and western and northern Australia. This includes locations like Aride Island Nature Reserve, Houtman Abrolhos, and Ashmore Reef.
Along the Arabian Peninsula and Persian Gulf, breeding colonies can be found from eastern Saudi Arabia to the United Arab Emirates. Pakistan and northwestern India represent the western extent of their range in tropical Asia.
Pacific Ocean
Royal terns nest on islands across Micronesia, Melanesia, and Polynesia in the tropical Pacific. Significant breeding sites include the Hawaiian Islands, Johnston Atoll, Northern Mariana Islands, Marshall Islands, and Ogasawara Islands.
In Southeast Asia, colonies occur along the coasts of the Philippines, Indonesia, Papua New Guinea, and northern Australia. Important locations include Tubbataha Reefs Natural Park and Ashmore Reef.
Habitat
Royal terns nest on low, exposed sites along marine coasts. Typical breeding habitat includes sandbars, barrier islands, coral islands, shell rakes, and gravel or rocky islets. They prefer flat, open areas with a sandy or coral substrate.
Access to clear, shallow water for foraging is essential. Royal terns usually feed within 5 km of nesting colonies but may range up to 20 km away in some cases.
Outside of the breeding season, these seabirds inhabit similar coastal habitats, as well as occur offshore around groups of islands. They roost on sandy beaches, rocky islets, jetties, breakwaters, and mudflats.
Migration
Northern populations of Royal terns migrate long distances after breeding. In North America, most individuals move down the Atlantic Coast or across the Gulf of Mexico to wintering grounds in the Caribbean, Gulf Coast, and Central and South America.
Some Royal terns also undertake trans-equatorial migrations between breeding locations in the Northern Hemisphere and wintering areas in the Southern Hemisphere. For example, birds that nest in West Africa migrate down the Atlantic coast to areas like Mauritania and Namibia.
Threats and Conservation Status
Royal terns currently have a conservation status of Least Concern on the IUCN Red List of Threatened Species. Their global population is estimated at 220,000 to 470,000 individuals.
However, Royal terns face threats in some regions from habitat degradation, pollution, human disturbance, and introduced predators at breeding colonies. Climate change impacts, such as sea level rise and increasing storm activity may also affect nesting areas.
Maintaining protected coastal habitats will be important for the future conservation of Royal tern populations. Educating people not to disturb nesting colonies can help reduce human impacts.
Conclusion
Royal terns have an extensive range across tropical and subtropical coastal regions of the Atlantic, Pacific, and Indian Oceans. They nest on sandy, exposed sites close to foraging areas. Northern populations migrate long distances after breeding.
While Royal terns remain relatively common overall, habitat degradation, human disturbance, and predators threaten breeding colonies in some locations. Protected coastal habitats and reducing disturbances will be key factors for the continued success of these elegant seabirds.