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Brown Booby (Sula leucogaster) Size: 65-75 cm (male), 70-80 cm (female); wing span 1.2 - 1.4 m (male), 1.3-1.5 m (female) Body mass: up to 1.0 kg (male), up to 1.3 kg (female) Wing loading [g/cm2]: ca. 0.64

Australia: Family Group 4 Family Group 4 Table Australian Pelican Red-tailed Tropicbird White-tailed Tropicbird Great Frigatebird Lesser Frigatebird Australasian Gannet Masked Booby Red-footed Booby Brown Booby Darter Great Cormorant Little Black Cormorant Little Pied Cormorant Pied Cormorant Black-faced Cormorant Imperial Shag Thumbnails page Family group table Index of bird names Habitat pages Key plants Birds home page

Similar species

Description     Classification     Distribution     Sightings     Photos     Breeding     Nest     Eggs     Behaviour     Food     Call/s

Physical description Click here for a physical description Brown Boobies are big seabirds with brown-and-white plumage. Seen from above, Brown Boobies are all dark-brown; on the underside the breast, belly, vent and greater coverts are white. Male Brown Boobies have a bluish facial mask, whereas females do not have any blue at the base of the yellowish-grey bill. The irises of both sexes are white. The legs and feet are yellowish-grey. In immature Brown Boobies the parts that are white in adults start off in mottled brown plumage, which gradually turns white. Juveniles have dark-brown plumage with a heavily mottled front.

Taxonomy, classification See Brown Booby at Wikipedia .

Range, habitat, finding this species Click here for information on habitat and range The overall distribution of this species can be assessed, and specific locations where birds have been spotted can be found, based on individual sighting reports submitted by birdwatchers to ebird.org . The global distribution of the Brown Booby is available HERE . There are 4 extant races of Brown Boobies, which are birds of the tropical oceans all around the globe. Nominate race "leucogaster" populates the Caribbean and Atlantic islands. Race "plotus" is present in the Pacific Ocean and westward to the Indian Ocean and the Red Sea. Race "brewsteri" is found along the Pacific coast of North America and Mexico, while race "etesiaca" lives along the coastlines of central America and in Colombia. Brown Boobies reach the Australian shores only in the northern half of the continent, from about Exmouth, WA, in the West to the QLD/NSW border in the East. Race "plotus" is found in coastal waters all along the Australian North coast and also all offshore islands in that range, from about Exmouth, WA, in the West to the QLD/NSW border in the East. Brown Boobies are commonly found on the open sea, coastal waters and offshore islands.

Sightings Click here for sighting information Race "plotus" M. Mearns reports spotting Brown Boobies, race "plotus", on Lady Elliot Island, off the QLD coast near Agnes Water, in January 2006 and again in January 2016. H. Mouritsen spotted a Brown Booby, race "plotus", on One Tree Island, Capricornia Cays NP, near Rockhampton, QLD, in January 2011. A. Ross-Taylor reports seeing Brown Boobies, race "plotus", from a cruiseship while in Australian territorial waters off the coast of QLD in April 2012. M. Eaton reports finding Brown Boobies, race "plotus", at Lady Musgrave Island, QLD, in September 2017, and at Cape Melville, Cape York peninsula, QLD, in August 2019. A breeding colony was found at Michaelmas Cay, QLD, in October 2024. Another Brown Booby was found off the coast of Hervey Bay, QLD, in September 2025. C. Pears spotted Brown Boobies, race "plotus", on a rocky stretch of coastline near Broome, WA, in July 2024. Another was found in the same area in June 2025. Race "leucogaster" A Brown Booby, nominate race "leucogaster", was found by us in Europe.

Photos

Race "plotus"

ADULT

PAIR

Many bird species exhibit sexual dimorphism, i.e., male and female have differing appearances which can be quite subtle.
In the case of the Brown Booby the difference lies in the colour of the facial skin - the male's facial mask, left, is bluish, the female's yellowish.

Lateral view of a pair of Brown Boobies, with the male on the right and the female on the left (photo courtesy of M. Mearns)
[Lady Elliot Island, near Agnes Water, QLD, January 2016]

MALE

Frontal view of two male Brown Boobies on their roost; note the bluish facial masks (photo courtesy of M. Mearns)
[Lady Elliot Island, near Agnes Water, QLD, January 2006]

Close-up lateral view of a male Brown Booby looking at the observer (photo courtesy of M. Eaton)
[Michaelmas Cay, QLD, October 2024]

Lateral view of a male Brown Booby looking at the observer (photo courtesy of B. Hensen)
[Darwin, NT, January 2016]

Close-up lateral view of a male Brown Booby looking towards the observer (photo courtesy of M. Eaton)
[Michaelmas Cay, QLD, October 2024]

Lateral view of a male Brown Booby (photo courtesy of B. Hensen)
[Darwin, NT, January 2016]

Frontal view of a male Brown Booby touching down on water (photo courtesy of M. Eaton)
[Off Hervey Bay, QLD, September 2025]

Lateral view onto the upperparts of a male Brown Booby in flight (photo courtesy of M. Eaton)
[Cape Melville, Cape York peninsula, QLD, August 2019]

Lateral/ventral view of a male Brown Booby in flight (photo courtesy of A. Ross-Taylor)

FEMALE

Lateral view of a female Brown Booby (photo courtesy of M. Mearns)
[Lady Elliot Island, near Agnes Water, QLD, January 2016]

Close-up near-dorsal view of a female Brown Booby (photo courtesy of M. Eaton)
[Michaelmas Cay, QLD, October 2024]

Dorsal view of a female Brown Booby looking backwards (photo courtesy of M. Mearns)
[Lady Elliot Island, near Agnes Water, QLD, January 2016]

Frontal view of a female Brown Booby in low flight; note the absence of a bluish facial mask (photo courtesy of C. Pears)
[Broome, WA, July 2024]

Near-frontal view of a female Brown Booby in flight (photo courtesy of H. Mouritsen)
[One Tree Island, Capricornia Cays NP, QLD, January 2011]

Lateral view of a female Brown Booby trying to catch a fish (photo courtesy of M. Eaton)
[Lady Musgrave Island, near Agnes Water, QLD, September 2017]

Near-dorsal view of a female Brown Booby in flight (photo courtesy of C. Pears)
[Broome, WA, July 2024]

Dorsal view of a female Brown Booby in low flight (photo courtesy of C. Pears)
[Broome, WA, July 2024]

IMMATURE/JUVENILE

Near-frontal view of an immature Brown Booby (photo courtesy of B. Hensen)
[Darwin, NT, January 2016]

Lateral view of an immature Brown Booby in flight, with a clear view of the underwing pattern (photo courtesy of B. Hensen)
[Darwin, NT, January 2016]

Close-up near-dorsal view of a Brown Booby chick that has left its nest, but cannot fly yet (photo courtesy of M. Eaton)
[Michaelmas Cay, QLD, October 2024]

Close-up near-dorsal view of a Brown Booby chick that has left its nest, with dad in attendance (photo courtesy of M. Eaton)
[Michaelmas Cay, QLD, October 2024]

Close-up frontal view of a Brown Booby chick begging to be fed (photo courtesy of M. Eaton)
[Michaelmas Cay, QLD, October 2024]

Race "leucogaster"

A Brown Booby, nominate race "leucogaster", was photographed by us in Europe.

Breeding information

Breeding season: Jan - Dec

Eggs: 1

Incubation period: ca. 43 days

Fledging age: ca. 100 days

Brown Boobies can breed all year round. Peak seasons are March-April and July-October. They can have more than one, in fact up to four, eggs. But only rarely does more than one chick survive long enough to fledge.

Nest building: Female & male

Incubation: Female & male

Dependent care: Female & male

Nest

"bungobittah", "lar", "malunna", "jindi" [bundjalung] = nest [Aboriginal]

Type: Scrape

Material: Sticks, sand, debris

Height above ground: N/A

Close-up near-dorsal view of a female Brown Booby shielding its chick in its nest (photo courtesy of M. Eaton)
[Michaelmas Cay, QLD, October 2024]

Dorsal view of a male Brown Booby shielding its young chick in its nest (photo courtesy of M. Eaton)
[Michaelmas Cay, QLD, October 2024]

Close-up lateral view of a male Brown Booby shielding its young chick in its nest (photo courtesy of M. Eaton)
[Michaelmas Cay, QLD, October 2024]

Close-up view of a pair of Brown Boobies at their nest, female sitting down on their single egg (photo courtesy of M. Eaton)
[Michaelmas Cay, QLD, October 2024]

Close-up lateral view of a male Brown Booby on its nest (photo courtesy of M. Eaton)
[Michaelmas Cay, QLD, October 2024]

Close-up near-frontal view of a female Brown Booby on its nest (photo courtesy of M. Eaton)
[Michaelmas Cay, QLD, October 2024]

Lateral overview of a female Brown Booby on its nest (photo courtesy of M. Eaton)
[Michaelmas Cay, QLD, October 2024]

Eggs

"boyanga", "booyanga", "derinya", "dirandil", "koomura", "mirk", "ngampu", "nooluk", "pateena", "pum-pum" = Egg; "dirundirri" = eggs [Aboriginal]; "gawu" = eggs [gamilaraay]

Size: 61 x 42 mm

Colour: Chalky white

Shape: Tapered oval

Close-up lateral view of a male Brown Booby ready to sit down on its egg (photo courtesy of M. Eaton)
[Michaelmas Cay, QLD, October 2024]

Close-up lateral view of a female Brown Booby turning its egg (photo courtesy of M. Eaton)
[Michaelmas Cay, QLD, October 2024]

Behaviour

The following photos show that mated pairs of Brown Booby work closely together when building their nest. Sometimes, when the male brought in sticks, they were dropped and thereby rejected. At other times, the female would grab the other end of a stick and they would place the stick together, as part of the nest. Given the rudimentary nature of the nests, this most likely has less to do with the quality of the nest construction than being part of a bonding ritual.

Male Brown Booby bringing a stick to its nest, where the female is waiting (photo courtesy of M. Eaton)
[Michaelmas Cay, QLD, October 2024]

Pair of Brown Boobies literally sharing the workload: "What do you think, honey? This stick HERE?!"
(photo courtesy of M. Eaton)
[Michaelmas Cay, QLD, October 2024]

Pair of Brown Boobies literally sharing the workload: "Yes, that feather fits THERE!" (photo courtesy of M. Eaton)
[Michaelmas Cay, QLD, October 2024]

These pages are largely based on our own observations and those of our contributors. The structure of these bird pages is explained HERE. For more salient facts on any bird species please refer to a field guide.

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