Because we live in Florida, we include seabirds among the feathered creatures we enjoy watching and studying (even though they’ll never visit our backyard feeders).
Along our favorite Gulf Coast beach, we’ve encountered hundreds of Royal Terns. Royal terns are very social, noisy, and live in colonies. In their nesting areas, their numbers can range literally into the thousands.
In our earliest search for information about this fascinating species, we were amazed to learn that the usually meticulous and observant birding authority, John J. Audubon, actually confused the Royal Tern and the Caspian Tern—two distinct species—depicting neither individually, but combining them into a species he called the Cayenne Tern in his amazing, monumental tome: Birds of America.
You usually hear a royal tern before you see one. Their loud “keer-reef” short, clear foraging call fills the summer beach air. The royal tern also has a more plover-like whistle that is longer and more melodious.
The royal tern lives on the coast and is only found near salt water. They usually feed near the shore, close to the beach or in backwater bays. Sometimes, they can be found foraging in open water about a hundred yards offshore when tasked with feeding chicks.
The first thing you notice about the royal tern is its conspicuous, scraggly black crest. It’s in stark contrast to its light grey upper parts and white face and under parts. Its bill is bright orange and its legs are black.
Adult royal terns of both sexes have an average wingspan of 51 inches. Their length is generally between 18 and 20 inches and they weigh between twelve ounces and a pound.
The royal tern feeds almost exclusively in salt water. (On very rare occasions has been known to hunt in fresh water.)
When feeding on fish, it dives into the water from about 30 feet high. They usually feed alone or in small groups of two or three. However, if there is a large school of fish, a much larger group can be seen hunting together.
A wide variety of small fish, like anchovies, are the main source of food for royal terns, but they also feed on shrimp, squid, and (on the Atlantic Coast) soft-shelled blue crabs that swim near the surface. Interestingly, when not hunting fish, the royal tern will alter its technique from the plunge dive from height to a shallow dive, so they can surprise their prey.
Courtship involves high spiraling flights by two or more birds. On the ground, the male presents food to female. Both the male and female bow and strut in circles.
The royal tern pair makes its nest by scraping a shallow depression in the sand. The nesting pair then defecates directly on the nest rim to reinforce the nest against flooding. The nest rim hardens after a few weeks. The nest may have a sparse lining of debris.
The female generally lays one egg (rarely, she may lay a second egg) in the scrape. The eggs incubate from 25 to 30 days.
After the eggs hatch, all the chicks in the colony congregate together in a group called a crèche (a pre-fledgling nursery for all the colony’s chicks). In a large colony there can be thousands of chicks in the crèche ranging in age from two to 35 days old. In the crèche, the chicks usually roam freely around the colony, but they are primarily fed by their own parents.
It seems remarkable, but parents and offspring recognize each other by voice, so that adults feed only their own young.
When the chicks are about a month old, they start to fly. Young royal terns remain with their parents for approximately eight months, even migrating south with them.
Royal terns mature around the age of 4 years, when they build their own nests and mate.
In winter, royal terns retreat south from the extreme northern edges of their range. A popular migration destination is the West Indies, but some routinely make their way to Suriname and Peru.
The oldest royal tern on record was found in 2013 in Belize. It had been banded in North Carolina 30 years earlier, in 1983.