Masked Booby (Sula dactylatra)

Masked Booby

[order] SULIFORMES | [family] Sulidae | [latin] Sula dactylatra | [UK] Masked Booby | [FR] Fou masque | [DE] Maskentolpel | [ES] Piquero Enmascarado | [NL] Maskergent

Subspecies

Genus Species subspecies Breeding Range Breeding Range 2 Non Breeding Range
Sula dactylatra TrO widespread
Sula dactylatra bedouti s and e Indian Ocean
Sula dactylatra californica islands off w Mexico
Sula dactylatra dactylatra Caribbean and sw Atlantic islands
Sula dactylatra fullagari Tasman Sea
Sula dactylatra melanops Red Sea, nw Indian Ocean
Sula dactylatra personata Coral Sea to Micronesia and Polynesia

Physical charateristics

Masked boobies are graceful birds, their body is white, they have black on thier wings and tails and a black mask around their beak and eyes. They are the biggest species of boobies. Females are larger than males, ranging from 75 to 86 cm long, males are from 74 to 82 cm long. They weigh from 1220 to 2353 g and have wingspans of 152 cm, on average. It is difficult to tell males and females apart because they both have bright white plumage as adults; young boobies are often mistaken for northern gannets (Morus bassanus). Masked boobies are born naked but are completely covered with feathers after 35 to 40 days. Juveniles are grey with white underparts and do not look like adults until their fourth year.

Listen to the sound of Masked Booby

[audio:http://www.aviflevoland.nl/sounddb/M/Masked Booby.mp3]

Copyright remark: Most sounds derived from xeno-canto

wingspan min.: 150 cm wingspan max.: 160 cm
size min.: 75 cm size max.: 86 cm
incubation min.: 42 days incubation max.: 45 days
fledging min.: 109 days fledging max.: 45 days
broods: 1   eggs min.: 2  
      eggs max.: 3  

Range

Tropical Ocean : widespread

Habitat

Boobies prefer to live on small, flat islands without trees. They often nest on the edges of cliffs or in flat areas that allow for easy take-off. They spend much of their time foraging over the ocean far from land.

Reproduction

Boobies have intricate mating rituals; males attract females by stretching out their necks and presenting gifts such as small stones and feathers to their perspective mates. After a slow walk they copulate; copulation takes ten to twenty seconds, and the female begins incubating immediately after laying the first egg.
Breeding seasons vary widely throughout the range of masked boobies; they can occur from February to August, January to July, and August to March. Masked boobies nest colonially; their nests are small hollows in the ground. The female usually lays two eggs. Incubation lasts 43 days on average. Masked boobies do not have brood patches, so they incubate the eggs with their feet. The first chick to hatch kicks the second chick out of the nest, so parents raise only one offspring. The chick fledges in 109 to 151 days and is intependent in one to two months. Juveniles reach sexual maturity in 3 to 5 years.
Both males and femles incubate the eggs. The first chick to hatch kicks the second chick out of the nest, so the parents only raise one offspring. Chicks are usually fed only once or twice a day. Both parents feed their young, but females may bring more food to the nest than males. Both parents continue to protect and feed their chick for one to two months after it fledges.

Feeding habits

Boobies have a diet consisting mostly of fish and squid. They catch their prey by diving from heights of up to 30 m. When collecting food for offspring, boobies usually tend to stay closer to land, otherwise they hunt around 65 km from shore.

Conservation

This species has a very large range, and hence does not approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence <20,000 km2 combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). Despite the fact that the population trend appears to be decreasing, the decline is not believed to be sufficiently rapid to approach the thresholds for Vulnerable under the population trend criterion (>30% decline over ten years or three generations). The population size has not been quantified, but it is not believed to approach the thresholds for Vulnerable under the population size criterion (<10,000 mature individuals with a continuing decline estimated to be >10% in ten years or three generations, or with a specified population structure). For these reasons the species is evaluated as Least Concern.
Masked boobies are fairly widespread; they are found primarily in the Atlantic and Pacific oceans. In the United States they are restricted to the three Hawaiian islands of Lehau, Moku Manu and Kaula. They are found mainly in the tropics. Masked boobies are found off the Yucatan peninsula and in much of South America. There are a variety of boobies with different ranges, but masked boobies are found on many islands between 30 degrees N and 30 degrees S, with tiny habitats from the Pacific to the Red Sea, and even on islands near Indonesia and Australia.
Masked Booby status Least Concern

Migration

Most adults spend all year in vicinity of colony. Extensive dispersal of young, and sometimes adults too; may forage over 1000 km from nearest land.

Distribution map

Masked Booby distribution range map

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