# Least Tern

Scientific name: Sternula antillarum

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

Canonical source: https://birdsofpuertorico.com/bird/130/Least-Tern

## Identification

The least tern (Sternula antillarum) is a species of tern that breeds in North America and locally in northern South America. It is closely related to, and was formerly often considered conspecific with, the little tern of the Old World. Other close relatives include the yellow-billed tern and Peruvian tern, both from South America.


## Distribution and habitat

The Least Tern is widespread and local in North America 
(Raffaele and others 1998), 
and winters off Central and 
South America (Oberle 2018). 
In the West Indies, it is a 
common breeding resident in 
The Bahamas, Greater Antilles, 
Cayman Islands, St. Martin, Antigua, and Barbuda mostly 
from May to August (Raffaele 
and others 1998). However, it 
is an uncommon breeder in the 
Virgin Islands and some of the 
other northern Lesser Antilles 
south to St. Christopher, while it 
ranges from uncommon to rare 
among the more southern Lesser 
Antilles (Raffaele and others 
1998). It is described as fairly 
common in the coastal areas 
of Puerto Rico, especially on 
the southwestern region where 
colonies of this species nest 
near the Cabo Rojo lighthouse 
(Biaggi 1997). On Vieques, it is 
a fairly common breeding visitor 
in summer, rare in fall, extremely 
rare in winter, and uncommon in spring (Gemmill 2015). It 
usually inhabits shallow coastal 
waters (Oberle 2018), harbors, 
and lagoons (Raffaele and 
others 1998), and more recently 
has been nesting on the roofs 
of shopping centers. The atlas 
fieldwork yielded a total of 82 
records within 46 hexagons or 10 
percent of the 479 total hexagons 
(see map). Of the 46 hexagons 
where this species was found, 
breeding met the atlas definition 
of confirmed in 33 percent (15) 
of the hexagons, probable in 7 
percent (3), and possible in 9 
percent (4), while the species 
was observed in 52 percent (24) 
of the hexagons but without 
evidence of breeding (see map).Least 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.       121Least Tern/Charrancito

## Breeding

Previously published reports indicate that the Least Tern 
breeds from April to July 
(Raffaele and others 1998). The 
nest consists of a scrape that can 
be located in a wide variety of 
habitats ranging from industrial 
sites (Raffaele and others 1998) 
and gravel-roofed buildings to 
undisturbed beaches (Oberle 
2018), and Least Terns either 
nest as single pairs or in colonies 
(Raffaele and others 1998). Atlas 
results show that this species 
breeds from April to August 
with the most breeding activity 
from May to July (see chart). 
Overall, the breeding activity 
peaks during May and June, and it mostly takes place within the 
subtropical dry forest life zone 
(see chart). Atlas results show 
that this species breeds mostly in 
southern coastal areas within the 
subtropical dry forest life zone 
(91 percent of the hexagons) and 
less commonly in the subtropical 
moist forest life zone (9 percent 
of the hexagons) (see table 
and map).

## Conservation

The current overall population trend of the Least Tern is 
described as decreasing, 
although some populations 
are increasing and others have 
unknown trends (Delany and 
Scott 2006). The Least Tern is currently listed as a species 
of least concern by the IUCN 
(BirdLife International 2018), 
and locally it is not listed in any 
of the threatened categories 
of PRDNER and USFWS. As 
a ground nester, the nests 
are subject to nest predation 
by mongooses (Herpestes 
auropunctatus), cats (Felis spp.), 
dogs (Canis spp.), and humans, 
which may cause breeding birds 
to abandon nests. In Puerto Rico, 
the Least Tern has a protected 
habitat in land of 18 percent or 
94 km2 of the total area covered by the hexagons where evidence 
of breeding was found for this 
species (527 km2).

Photo: https://birdsofpuertorico.com/static/images/webp/in_130_Im0.png.webp

Distribution map: https://birdsofpuertorico.com/static/images/webp/in_130_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.