Masked booby

Sula dactylatra

The masked booby is a large seabird of the booby family, Sulidae. This species breeds on islands in tropical oceans, except in the eastern Atlantic; in the eastern Pacific it is replaced by the Nazca booby, "Sula granti", which was formerly regarded as a subspecies of masked booby.
Masked Booby - Sula dactylatra      Bird,Masked Booby,Mexico,Sula dactylatra

Appearance

This is the largest booby, at 74–91 cm long, with a 137–165 cm wingspan and 1.2–2.35 kg weight. Adults are white with pointed black wings, a pointed black tail, and a dark grey facemask. The sexes are similar, but the male has a yellow bill, and the female's is greenish yellow; during the breeding season they have a patch of bare, bluish skin at the base of the bill. Juveniles are brownish on the head and upperparts, with a whitish rump and neck collar. The underparts are white. Adult plumage is acquired over two years.

The masked booby is silent at sea, but has a reedy whistling greeting call at the nesting colonies. While on the breeding grounds, these birds display a wide range of hissing and quacking notes.
Masked booby (Sula dactylatra) Daymaniyat Islands, N Oman. Oct 20, 2015. Fall,Geotagged,Masked booby,Oman,Sula dactylatra

Naming

It is also called the masked gannet or the blue-faced booby.
Masked Booby Juvenile An unfortunately bad shot of a very cool bird! Geotagged,Masked Booby,Masked Booby juvenile,Masked booby,Spring,Sula,Sula dactylatra,United States,bird

Behavior

Masked boobies are spectacular divers, plunging diagonally into the ocean at high speed. They mainly eat small fish, including flying fish. This is a fairly sedentary bird, wintering at sea, but rarely seen far away from the breeding colonies. However, Caribbean birds occasionally wander north to warm southern Gulf Stream waters off the eastern seaboard of the United States. More remarkably, there have been three western Palaearctic records of masked booby, presumably "dactylatra", all from Spanish waters, although one of these also entered French territorial areas.

Reproduction

The masked booby nests in small colonies, laying two chalky white eggs on sandy beaches in shallow depressions, which are incubated by both adults for 45 days. In most cases, the first chick will kill its smaller, weaker sibling after it hatches. Siblicide has been well studied in this species; researchers such as David Anderson have demonstrated that while the boobies can manage to feed two chicks if siblicide is prevented, they do so at a steep penalty to health and future reproductive success.

Compared to other species of boobies such as the blue-footed booby, siblicide is obligatory in the masked booby. One reason is because the masked boobies build very shallow flat nests, so older chicks can expel their younger siblings with relative ease. Blue-footed booby parents, meanwhile, build nests with steeper sides, thus preventing some older chicks from engaging in siblicidal behaviour.

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Status: Least concern
EX EW CR EN VU NT LC
Taxonomy
KingdomAnimalia
DivisionChordata
ClassAves
OrderSuliformes
FamilySulidae
GenusSula
SpeciesS. dactylatra