# Royal Tern

Scientific name: Thalasseus maximus

Bird group: [gull](https://birdsofpuertorico.com/family/gull)

Canonical source: https://birdsofpuertorico.com/bird/134/Royal-Tern

## Identification

The royal tern (Thalasseus maximus) is a tern in the family Laridae. The species is endemic to the Americas, though strays have been identified in Europe.
  Adult royal tern and sandwich tern (right) in flight at Core Banks, North Carolina.

## Threats

The royal tern has few predators when it is mature, but before the chicks hatch or while they are chicks the tern is threatened by humans, other animals, and the tides.[17] Humans threaten terns by fishing and by disrupting the tern nesting sites. Fishing nets can catch a tern while it is diving, making it unable to feed or it may cause it to drown if it is caught under water. Animals such as foxes, raccoon, and large gulls prey on tern chicks and tern eggs.


## Distribution and habitat

The Royal Tern occurs on the western coast of Africa (Biaggi 
1997, Oberle 2018, Raffaele 
and others 1998) and from the 
Southern United States through 
much of coastal South America 
including the West Indies 
(Raffaele and others 1998). In 
Puerto Rico, it is a common 
visitor during winter in the San 
Juan Harbor, Laguna San José, 
Laguna Torrecilla, Boquerón Bay, 
and Mayagüez (Oberle 2018). 
On Vieques, it is considered 
a common non-breeder in all 
seasons (Gemmill 2015). It has 
been known to nest on Mona 
(McCandless 1958) and cays near Culebra (Kepler and Kepler 1978, 
Oberle 2018). It usually inhabits 
coastal marine waters (Oberle 
2018), harbors, and lagoons 
(Raffaele and others 1998). The 
atlas fieldwork yielded a total of 
134 records within 82 hexagons 
or 17 percent of the 479 total 
hexagons (see map). Of the 82 
hexagons where the Royal Tern 
was found, breeding met the 
atlas definition of confirmed in 4 
percent (3) of the hexagons and 
probable in 1 percent (1), while 
the species was observed in 95 
percent (78) of the hexagons but 
without evidence of breeding 
(see map). Royal Tern distribution. The map shows the highest breeding code by hexagon and overlaying the ecological life zones in 
Puerto Rico. Note: percentages may not total 100 due to rounding.       125Royal Tern/Charrán Real

## Breeding

Previously published reports indicate that the Royal Tern 
breeds from April to July but 
is irregular as to number of 
pairs and location (Raffaele and 
others 1998). Nesting is generally 
colonial and on small cays, and 
the nest consists of a scrape 
made on a sandy beach or in a 
rocky depression (Oberle 2018, 
Raffaele and others 1998). Atlas 
results show that this species 
breeds during May and June 
(see chart). Overall, the breeding 
activity peaks in June, and it 
mostly takes place within the 
subtropical dry forest life zone 
(see chart). Results show that this species breeds in coastal areas 
mostly within the subtropical dry 
forest life zone (75 percent of the 
hexagons) (see table), but it also 
breeds within the subtropical 
moist forest life zone (25 percent 
of the hexagons) (see table 
and map).

## Conservation

The current overall population trend of the Royal Tern is 
described as stable, although 
some populations have unknown 
trends (Wetlands International 
2012), and it is currently listed 
as a species of least concern by 
the IUCN (BirdLife International 
2018). In Puerto Rico, Oberle (2018) noted that the only 
confirmed breeding sites for 
Royal Terns were on cays off 
Culebra, but that breeding on 
these sites was reduced since 
1988 to just a “sporadic handful 
of breeding pairs.” Locally, this 
species is not listed in any of the 
threatened categories of PRDNER 
and USFWS.In Puerto Rico, the Royal Tern has a protected habitat in land of 
3 percent or 3 km2 of the total area covered by the hexagons 
where evidence of breeding was 
found for this species (95 km2).

Photo: https://birdsofpuertorico.com/static/images/webp/in_134_Im0.png.webp

Distribution map: https://birdsofpuertorico.com/static/images/webp/in_134_Im1.png.webp

Source note: Text is reproduced from this site's published record. Historical conservation statements and taxonomy have not been independently revalidated. See https://birdsofpuertorico.com/about for source credits and limitations.