Fregata magnificens

Geographic Range

Magnificent frigatebirds live along American, tropical coastlines. They breed as far north as 25 degrees north latitude in Mexico and Florida and as far south 27 degrees south latitude in Brazil. They are especially common in southern Florida, the Gulf Coast, the Caribbean islands and the west coast of Mexico.

• Biogeographic Regions
• nearctic nearctic
  • native native

Habitat

Magnificent frigatebirds usually build their nests out of twigs on or around low-lying vegetation. Males gather twigs and other nest building materials while females remain at the males' display site and build the nest there. Nests are primarily constructed at ground level, but sometimes in trees as well. Nests are flat or slightly hollow with a diameter of 25 - 35 cm. They are usually fully exposed to the sun for the birds' sunning habits. A colony of magnificent frigatebirds can occupy about 500 m of shoreline with a total area of about 22,500 m squared. A colony with about 2500 pairs of birds in Barbuda, a small island in the Caribbean, is the largest known colony.

• Habitat Regions
• tropical tropical
• terrestrial terrestrial
• saltwater or marine saltwater or marine

• Aquatic Biomes
• coastal coastal

• Other Habitat Features
• estuarine estuarine

Physical Description

Male magnificent frigatebirds are entirely black except for brown inner secondaries on the upper wing and the presence of a red inflatable throat pouch called a gular sac. They also have faint purple gloss on the head and green on the neck, scapulars, and upper wing. Their legs and feet appear back or grayish. Females are also entirely black with a white chest and white and tan markings on the wings. Their legs and feet are flesh-colored or pink, and they lack a gular sac. Females are, in general, 15% larger than males. Immature magnificent frigatebirds have a white head and chest while the rest of the body is black. Their legs, feet, and bill are light-bluish gray.

Their large heads, long, pointed, narrow wings, and forked tails make them easy to distinguish even from a distance. They are most often seen soaring along coastlines at higher altitudes and their silhouette is readily recognizable. They are also recognizable by their large size and long, hooked bill. They have short legs and small feet not well-suited to walking or swimming.

• Other Physical Features
• endothermic endothermic
• homoiothermic
• bilateral symmetry bilateral symmetry

• Sexual Dimorphism
• female larger
• sexes colored or patterned differently
• male more colorful
• ornamentation ornamentation

Reproduction

During the breeding season, male magnificent frigatebirds congregate at male display sites. They inflate their large, red, gular sacs. These sacs, while inflated, can get so large that they obscure the bird's head. Males rapidly vibrate their wings and sit back on their tails. They stretch their wings out and throw their heads back for maximum display of the gular sac. Females then inspect the males. As females attempt to find a preferred mate, males twist and bend to make their gular sac look as large a possible, they also make a loud, drumming noise during this display. Magnificent frigatebirds form monogamous pairs each breeding season once females have selected mates. However, they rarely maintain the same partner from season to season.

• Mating System
• monogamous monogamous

Female magnificent frigatebirds lay a single egg three to four weeks after the beginning of breeding season. The incubation period for this species is not recorded, but has been estimated at 50 days. Because female parent involvement continues for much longer than male parental involvement, females only mate every other year. Males rarely care for their young longer than six months and breed annually. Juveniles near mature mass before fledging. Age of sexual maturity is not known but none breed until plumage is in mature phase.

• Key Reproductive Features
• iteroparous iteroparous
• seasonal breeding seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• oviparous oviparous

A magnificent frigatebird's egg is almost never exposed, being nearly continuously monitored by a parent. Hatchlings are altrical and are usually protected beneath a brooding parent. After about three weeks they are left alone in the nest for approximately half of daylight hours as parent birds search for food. Both parents contribute to provisioning hatchlings, but males contribute less than 40% of feeding. Around the sixth week the hatchling is substantially developed and can defend itself. At about the eleventh week, the male parent abandons the nest, leaving remaining parenting to the female. Females then compensate by nearly doubling the food provided for the hatchling. Females continue to feed hatchlings until they fledge and leave the nest. Often involvement continues after fledging, up to approximately four months.

• Parental Investment
• altricial altricial
• pre-fertilization
  • provisioning
  • protecting
    • female
• pre-hatching/birth
  • protecting
    • male
    • female
• pre-weaning/fledging
  • provisioning
    • male
    • female
• pre-independence
  • provisioning
    • female

Lifespan/Longevity

While there is little data on magnificent frigatebird lifespan, it is estimated at 30 years. Besides natural death, mortality is occasionally caused by destructive hurricanes and man-made interferences in colonies.

Behavior

Magnificent frigatebirds are birds of the open ocean. Although their nests are on coastal areas, these birds are in flight for a majority of the time. Often they fly long distances over open water far from land. Their wings are so large that flying is nearly effortless. They take advantage of updrafts and can glide for long distances without beating their wings. They use their long, forked tails for maneuvering. They are one of the only birds with the ability to ride out a hurricane's strong winds. While usually solitary in flight, they do nest in colonies with numerous other pairs. While feeding, they can be extremely aggressive towards other animals. They are otherwise docile and while on land will often allow humans to come very close and even touch them. While their legs are not well-suited to walking, their strong, webbed toes allow them to perch when not in flight. Aggression, while rare, is usually in the form of bill snapping and jabbing at other birds when competing for perch sights. They do not defend territory beyond their small nest areas. Fledglings' often interact in playful ways.

• Key Behaviors
• arboreal arboreal
• flies
• diurnal diurnal
• motile motile
• sedentary sedentary
• solitary solitary
• colonial colonial

Home Range

There is no information available on the home ranges of magnificent frigatebirds.

Communication and Perception

Magnificent frigatebirds are usually silent, but they do vocalize when approaching a colony, when begging for food (hatchlings), and during mating displays. Little is known about communication among frigatebirds.

• Communication Channels
• visual visual
• acoustic acoustic

• Perception Channels
• visual visual
• tactile tactile
• acoustic acoustic
• chemical chemical

Food Habits

Magnificent frigatebirds eat mainly fish, as well as squid, jellyfish, and crustaceans. However, their diet can greatly vary due to food availability and preferred hunting technique. The three main hunting techniques are dipping, kleptoparasitism, and opportunistic feeding. When dipping, these birds gracefully glide just above the surface of the water and skim the surface with their beak to catch fish. However, they are only able to dip about 15 cm deep to avoid getting their feathers wet. Kleptoparasitism, the stealing of another animal’s food, is how this species gets one of their nicknames, "Man-'o-War". They chase other birds, particularly gulls , gannets , terns , and boobies . This chase continues until the victim is forced to disgorge their food. Magnificent frigatebirds then catch the disgorged food in mid air. They may also catch the other bird by the tail feathers and shake it until they release their food. Opportunistic feeding involves eating garbage, young turtles at hatching, and otherwise taking advantage of all available food sources. Magnificent frigatebirds eat fish scraps discarded by boats, offal (discarded parts of animals unfit for consumption) from slaughterhouses, and other garbage. Occasionally they steal food from the hands of humans. Females consume more than males because of their larger size and greater contribution to the feeding of hatchlings.

• Primary Diet
• carnivore carnivore
  • piscivore piscivore

• Animal Foods
• fish
• mollusks
• aquatic crustaceans
• cnidarians

Predation

There are no known birds that prey on magnificent frigatebirds. Mammals may sometimes take eggs and nestlings. However, magnificent frigatebirds closely monitor their eggs and hatchlings until they are fairly able to defend themselves and breeding occurs in colonies, where many eyes can keep watch for predators.

Ecosystem Roles

Magnificent frigatebird feeding habits affect their fish prey, especially flying fish ( Exocoetidae ), as well as some squid and crustaceans. Other birds like pelicans , gulls , gannets , terns , and boobies are affected by magnificent frigatebird kleptoparasitism. Magnificent frigatebirds are often found near groups of dolphins , tuna , or other predatory fish that drive much of their prey to the surface of the water. This makes magnificent frigatebirds more successful when using a dipping hunting technique.

Economic Importance for Humans: Positive

Magnificent frigatebirds are beautiful and may attract ecotourism. They are also important members of the healthy ecosystems they inhabit.

• Positive Impacts
• ecotourism ecotourism

Economic Importance for Humans: Negative

There are no known negative impacts of magnificent frigatebirds on humans.

Conservation Status

There are an estimated 50,000 to 71,000 breeding pairs of magnificent frigatebirds. Their numbers are apparently declining, due to human disturbances to nesting areas. There is a need for more research and protection plans in order to ensure that magnificent frigatebird populations remain stable. Regulations have been proposed to the Government of Antigua and Barbuda, but there is no current legal protection for this species.

Additional Links

Encyclopedia of Life

Contributors

Tanya Dewey (editor), Animal Diversity Web.

Martha Calcutt (author), University of Notre Dame, Karen Powers (editor, instructor), Radford University.

References

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Osorno, J., T. Székely. 2004. Sexual conflict and parental care in magnificent frigatebirds: full compensation by deserted females. Animal Behaviour , 68/2: 337-342. Accessed April 11, 2006 at http://www.sciencedirect.com.lib-proxy.nd.edu/science?_ob=ArticleURL&_udi=B6W9W-4CPVK9Y-4&_coverDate=08%2F31%2F2004&_alid=389439147&_rdoc=1&_fmt=&_orig=search&_qd=1&_cdi=6693&_sort=d&view=c&_acct=C000022718&_version=1&_urlVersion=0&_userid=489835&md5=59d9f51c4becb9aa162484889444003b .

Osorno, J. 1999. Offspring desertion in the Magnificent Frigatebird: are males facing a trade-off between current and future reproduction?. Journal of Avian Biology , 30: 335-341.

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Trivelpiece, W., J. Ferraris. 1987. Notes ont eh behavioural ecology of the magnificent frigatebird Fregata magnificens. Ibis , 129/2: 168-174. Accessed April 11, 2006 at http://www.csa.com/partners/viewrecord.php?requester=gs&collection=ENV&recid=1646941&q=&uid=&setcookie=yes .

UC Regents. 1995. "USGS" (On-line). Fregata magnificens. Accessed April 11, 2006 at http://pick4.pick.uga.edu/mp/20q?search=Fregata+magnificens&guide=Birds&cl=US/MA&flags=not_no: .