# Brown Booby

Scientific name: Sula leucogaster

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

Canonical source: https://birdsofpuertorico.com/bird/148/Brown-Booby

## Identification

The brown booby (Sula leucogaster) is a large seabird of the booby family, Sulidae, of which it is perhaps the most common and widespread species. It has a pantropical range, which overlaps with that of other booby species. The gregarious brown booby commutes and forages at low height over inshore waters. Flocks plunge-dive to take small fish, especially when these are driven near the surface by their predators. They only nest on the ground, and roost on solid objects rather than the water surface.
The booby's head and upper body (back) is covered in dark brown to black plumage, with the remainder (belly) being a contrasting white. The bare part colours vary geographically, but not seasonally. The species also displays sexual dimorphism of the bare part colours, the males having a blue orbital ring, as opposed to the yellow orbital ring of the female. In addition the male of subspecies S. l. brewsteri is distinctly plumaged in having the forehead, forecrown and chin white, merging to a greyish brown neck and breast.


## Distribution and habitat

The Brown Booby occurs through the tropical and 
subtropical oceans of the world 
(Raffaele and others 1998). It is a 
fairly common resident in Puerto 
Rico (Raffaele and others 1998), 
especially in the far eastern and 
western coasts (Oberle 2018), 
and a fairly common non-
breeding resident on Vieques 
from December to May but 
uncommon to rare at other times 
of the year (Gemmill 2015). This 
seabird is generally seen in rocky 
cays, on islets, and out at sea. It 
has a large breeding colony on 
Mona (Raffaele 1989a), although 
the largest colonies are currently 
found in La Cordillera Natural Reserve between Fajardo and 
Culebra (Oberle 2018), while 
the large colony on Desecheo 
was eliminated shortly after the 
introduction of rhesus monkeys 
(Macaca mulatta) (Oberle 2018). 
The atlas fieldwork yielded a 
total of 93 records within 52 
hexagons or 11 percent of the 
479 total hexagons (see map). 
Of the 52 hexagons where this 
species was found, breeding met 
the atlas definition of confirmed 
in 17 percent (9) of the hexagons 
and possible in 10 percent (5), 
while the species was observed 
in 73 percent (38) of the 
hexagons but without evidence 
of breeding (see map). Brown Booby 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.      139Brown Booby/Boba Parda

## Breeding

This species usually nests on the ground on remote islands 
or inaccessible sea cliffs, 
and breeding season peaks 
from March to June and from 
September to October, according 
to previously published reports 
(Raffaele and others 1998). Atlas 
results show that the Brown 
Boobys breeding activity peaks 
in July (see chart). Results show 
that the Brown Booby breeds 
within the subtropical dry forest 
life zone (100 percent of the 
hexagons) in associated islands 
and cays around Puerto Rico 
including Culebra, Mona and Monito, Desecheo, and Arrecifes 
de La Cordillera (see table 
and map).

## Conservation

The Brown Booby is listed as a species of least concern by 
the IUCN (BirdLife International 
2018), while locally this species 
is not listed in any of the 
threatened categories used by 
PRDNER and USFWS. In Puerto 
Rico, the Brown Booby has a 
protected habitat in land of 17 
percent or 57 km2 of the total area covered by the hexagons 
where evidence of breeding was 
found for this species (336 km2). 

Photo: https://birdsofpuertorico.com/static/images/webp/in_148_Im0.png.webp

Distribution map: https://birdsofpuertorico.com/static/images/webp/in_148_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.