Geographic Range
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.
- Biogeographic Regions
- oriental
- ethiopian
- neotropical
- australian
- oceanic islands
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.
- Habitat Regions
- tropical
- terrestrial
- saltwater or marine
Physical Description
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
(
Sula 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.
- Other Physical Features
- endothermic
- bilateral symmetry
- Sexual Dimorphism
- sexes alike
- female larger
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.
- Mating System
- monogamous
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.
- Key Reproductive Features
- iteroparous
- year-round breeding
- gonochoric/gonochoristic/dioecious (sexes separate)
- sexual
- oviparous
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.
- Parental Investment
- no parental involvement
- altricial
-
pre-hatching/birth
-
protecting
- male
- female
-
protecting
-
pre-weaning/fledging
-
provisioning
- male
- female
-
protecting
- male
- female
-
provisioning
-
pre-independence
-
provisioning
- male
- female
-
protecting
- male
- female
-
provisioning
Lifespan/Longevity
Masked Boobies have a lifespan of 15 to 20 years; the longest known lifespan is 20
years.
Behavior
Masked boobies usually nest colonially. They are quick to sound an alarm if suprised
or threatened but are not aggressive and are sometimes friendly to humans. Masked
boobies spend most of their time out at sea in search of food. They usually feed diurnally.
Home Range
We do not have information on home range for this species at this time.
Communication and Perception
Males have a high-pitched whistle while females have a more "honky" sounding call.
Males will communicate by calling during their courtship displays or when they are
frightened or alarmed. Females only call for help and as a warning. Both sexes are
usually silent at night.
Food 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.
- Primary Diet
- carnivore
- Animal Foods
- fish
- mollusks
Predation
There are no known predators of masked boobies. Because they are not usually found
in dense populations and because they nest on islands, it might be hard for predators
to rely on them as prey.
Ecosystem Roles
Because masked boobies do not occur in dense populations, they do not seriously affect
fish populations where they feed, nor are they important food sources for predators.
Economic Importance for Humans: Positive
Fishermen sometimes find schools of tuna by following feeding boobies; without knowing
it, boobies provide fisherman with information on the best places to find fish. Boobies
are also popular among birdwatchers.
- Positive Impacts
- ecotourism
Economic Importance for Humans: Negative
There are no known adverse affects of masked boobies on humans.
Conservation Status
Interactions with humans seem to have had little effect on the species. Thousands
of tourists pass close by their nests in the Galapagos, seemingly without any negative
effects. Though there have been a few cases of boobies caught in fishing traps, these
numbers are reportedly small.
Additional Links
Contributors
Alaine Camfield (editor), Animal Diversity Web.
Paul Mansoor (author), University of Michigan-Ann Arbor, Phil Myers (editor), Museum of Zoology, University of Michigan-Ann Arbor.
- oriental
-
found in the oriental region of the world. In other words, India and southeast Asia.
- native range
-
the area in which the animal is naturally found, the region in which it is endemic.
- Ethiopian
-
living in sub-Saharan Africa (south of 30 degrees north) and Madagascar.
- native range
-
the area in which the animal is naturally found, the region in which it is endemic.
- Neotropical
-
living in the southern part of the New World. In other words, Central and South America.
- native range
-
the area in which the animal is naturally found, the region in which it is endemic.
- Australian
-
Living in Australia, New Zealand, Tasmania, New Guinea and associated islands.
- native range
-
the area in which the animal is naturally found, the region in which it is endemic.
- oceanic islands
-
islands that are not part of continental shelf areas, they are not, and have never been, connected to a continental land mass, most typically these are volcanic islands.
- native range
-
the area in which the animal is naturally found, the region in which it is endemic.
- tropical
-
the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.
- terrestrial
-
Living on the ground.
- saltwater or marine
-
mainly lives in oceans, seas, or other bodies of salt water.
- pelagic
-
An aquatic biome consisting of the open ocean, far from land, does not include sea bottom (benthic zone).
- coastal
-
the nearshore aquatic habitats near a coast, or shoreline.
- monogamous
-
Having one mate at a time.
- iteroparous
-
offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).
- year-round breeding
-
breeding takes place throughout the year
- sexual
-
reproduction that includes combining the genetic contribution of two individuals, a male and a female
- oviparous
-
reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.
- altricial
-
young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.
- diurnal
-
- active during the day, 2. lasting for one day.
- motile
-
having the capacity to move from one place to another.
- nomadic
-
generally wanders from place to place, usually within a well-defined range.
- social
-
associates with others of its species; forms social groups.
- colonial
-
used loosely to describe any group of organisms living together or in close proximity to each other - for example nesting shorebirds that live in large colonies. More specifically refers to a group of organisms in which members act as specialized subunits (a continuous, modular society) - as in clonal organisms.
- visual
-
uses sight to communicate
- acoustic
-
uses sound to communicate
- ecotourism
-
humans benefit economically by promoting tourism that focuses on the appreciation of natural areas or animals. Ecotourism implies that there are existing programs that profit from the appreciation of natural areas or animals.
- carnivore
-
an animal that mainly eats meat
- piscivore
-
an animal that mainly eats fish
- molluscivore
-
eats mollusks, members of Phylum Mollusca
- endothermic
-
animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.
- bilateral symmetry
-
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
- visual
-
uses sight to communicate
- tactile
-
uses touch to communicate
- acoustic
-
uses sound to communicate
- chemical
-
uses smells or other chemicals to communicate
References
Anderson, D. 1993. Sula dactylatra - Masked Booby. The Birds of North America , No. 73, 1993: 1-16.
Great Barrier Reef - Reef Education, 1996. "GBR Explorer - Boobies" (On-line). Boobies. Accessed April 20, 2004 at http://www.reefed.edu.au/explorer/animals/marine_vertebrates/seabirds/boobies.html .
Kepler, C. 1969. Breeding Biology of the Blue-Faced Booby on Green Island, Kure Atoll . Cambridge, MA: Nuttall Ornithological Club.
National Wildlife Refuge, 2000. "Masked Booby" (On-line). Accessed April 20, 2004 at http://midway.fws.gov/wildlife/mabo.html .