Birds of paradise

views updated Jun 08 2018

Birds of paradise

Description

Habitat and diet

Mating behavior

Habitat loss

Resources

The birds of paradise are some of the most fascinating birds in the world. This is due to the striking coloration of the males of most species, and the wide range of behaviors demonstrated in the group. Researchers of animal behavior are particularly interested in the elaborate mating displays performed by male birds of paradise.

Birds of paradise are members of the family Paradisaeidae, which probably evolved on the island of New Guinea. The family is comprised of 42 species, 38 of which are found mainly or entirely on New Guinea. Two species are found only in the Moluccan Islands to the west of New Guinea, and four others are found mainly or entirely in northeastern Australia. Included within the family are such birds as astrapias, manucodes, paradisaeas, parotias, riflebirds, and sicklebills.

Description

The birds of paradise have a crow-like body shape, with strong feet and bill. However, in some species this basic pattern has been modified substantially. For example, the sicklebills have evolved a long, curved beak used to probe for insects in thick moss and tree-bark. In many species the plumage of the males is modified with fantastic plumes, streamers, and wiry head and tail extensions. Although the body of most of the birds of paradise is 1017 in (2545 cm) long, the head plumes may reach 16 in (40 cm) in length, and the tail feathers up to 27 in (70 cm) long.

The females of most species are colored drab buff to black, with patterning that helps them remain hidden in the forest canopy while sitting on a nest. (This type of coloration is called cryptic.) Nests of most species are cup-shaped, and are built in forks of trees using leaves, twigs, and other plant material. Females lay one or two eggs, which average 1.4 in (37 mm) long and 1 in (26 mm) wide. Incubation periods are 1721 days, and young birds remain in the nest 1730 days.

Habitat and diet

New Guinea is an extremely mountainous island. Its equatorial location results in a tropical climate near sea level, but cooler conditions higher in the mountains. In fact, the highest peaks have glaciers. In addition, the prevailing oceanic winds carry moisture-laden air over the island, resulting in as much as 27 ft (8.5 m) of rain per year in some places. Sites on the lee side of mountains, however, may be quite dry. The great variations of climate in New Guinea result in numerous different habitats. The various species of birds of paradise are rather specific to particular kinds of habitat. For example, the crested bird of paradise (Cnemophilus macgregorii ) is only found in upper montane forest and subalpine shrubland, while the trumpet manucode (Manucodia keraudrenii ) is found only in lowland and lower mountain forests, and the blue bird of paradise (Paradisaea rudolphi ) prefers mid-montane forest.

In addition to inhabiting different ecological zones in New Guinea, the various birds of paradise use different food resources. The two basic kinds of foods eaten are fruits and insects. There are also two groups of fruits: simple fruits rich in carbohydrates, such as figs, and complex fruits with high levels of fat and protein, such as those of mahogany and nutmeg. Species of birds of paradise tend to eat mainly simple fruits (e.g., the trumpet manucode), mainly complex fruits (e.g., the raggiana bird of paradise, Paradisaea raggiana ), or complex fruits plus significant quantities of insects (e.g., the magnificent bird of paradise, Cicinnurus magnificus ).

When animals eat tree fruits, they may also digest the seeds, or the seeds may pass through the digestive system intact. If seeds are not digested, a tree seedling may sprout from them, helping the forest regenerate. In most forest habitats worldwide, the main fruit-dispersing animals are mammals. In New Guinea, however, this role is largely played by birds of paradise, which eat fruits and distribute the seeds, helping to ensure the dispersal of important species of forest trees.

Mating behavior

Polygynous birds of paradise

As mentioned above, many species of birds of paradise are sexually dimorphic, meaning the males and females have different appearances. The males have elaborate plumage patterns, which are used in their mating displays. The females of these species are drab and cryptic. Sexually dimorphic species are usually also polygynous, meaning the males may mate with more than one female. To attract a female, a male may perform a mating dance on the ground while conspicuously displaying its bright plumage and calling loudly, or it may display while perched on a shrub, or while hanging upside down on a tree branch. Males may perform these displays alone, or in competitive groups in a place called a lek. The females watch the displays and choose which male to mate with. The female choice appears to be based on the vigor of the display of the male, and the condition and color of his feathers. By choosing a vigorous mate, the female presumably ensures that her offspring will also be relatively healthy. Therefore, the strongest, most brightly-feathered males have a better chance of being chosen as a mate by females, while less attractive males may be passed over. The elaborate plumage of the males is thought to have evolved through this evolutionary process of sexual selection (i.e., females choosing mates on the basis of their desirable behavioral and anatomic traits, including color). After mating, the female returns to her nest and raises her offspring alone.

Researchers have noticed a relationship between the mating system and diet in the birds of paradise. Polygynous bird of paradise species that display in leks (such as the raggiana bird of paradise) tend also to eat mainly complex fruits. This is thought to be because females searching for these fruits fly long distances in the forest, and thus are likely to encounter groups of males displaying together. Polygynous species in which solitary males display (such as the magnificent bird of paradise) tend to eat insects plus complex fruits. To catch insects, females need not fly long distances, so a male is more likely to be seen and chosen as a mate if he displays alone near the small home range of the female.

Interestingly, the polygynous birds of paradise also show sexual bimaturism. This means that males and females become sexually mature at different ages. Females of these species are thought to begin to breed when 23 years old, while males do not acquire mature plumage (and do not breed) until age 47 years. However, males of these species will grow adult plumage at a younger age when kept alone in captivity. This suggests that the delay in male maturation in the wild is due to hormonal suppression related to the presence of already-mature adult males.

Monogamous birds of paradise

Nine species of birds of paradise, including the manucodes, are sexually monomorphic. The males and females have coloring that is the same or nearly so (they tend to be brown or black), and both lack the elaborate plumage that characterizes most other birds of paradise. These species are monogamous, meaning the males and females mate with only one partner at a time, and in some species pair for life. As in most monogamous species, the males help the females raise the young.

These species typically feed mainly on simple fruits, such as figs. This type of fruit is relatively low in nutrients, compared to complex fruits and insects. Scientists think that the monogamous mating system may have developed in these species because two parents are necessary to provide enough nutrition to

KEY TERMS

Cryptic Drab, usually brownish coloration that makes an organism difficult to see in its natural habitat and allows it to hide from predators.

Lek A central area in which many males of a species perform mating displays simultaneously.

Montane Habitat on relatively cool, moist mountain slopes below the tree line.

Sexual bimaturism A condition in which the males and females of a species become sexually mature at different ages.

Sexual dimorphism The occurrence of marked differences in coloration, size, or shape between males and females of the same species.

Subalpine Habitat on high mountain slopes, above the treeline.

raise the young. Thus, in the birds of paradise, it appears that the diet of a species has influenced the evolution of its social system.

Habitat loss

Although much of New Guinea is still covered with rainforest, extensive areas are being logged or converted to agriculture. Moreover, because of population growth and economic development the habitat destruction by deforestation will increase in the future. Some species of birds of paradise are found in highly limited ranges, so deforestation of their local habitat could result in their extinction. Other species are found throughout New Guinea, but only within a particular altitudinal range. For example, the blue bird of paradise occurs only between 4,200 and 5,900 ft (1, 300-1,800 m). This species is under pressure from habitat loss associated with human colonization at these altitudes and is classified as vulnerable by the World Conservation Union (IUCN).

In addition to habitat loss, many species are threatened by overhunting. After Europeans discovered the birds, the demand for their plumage to use as decoration increased, so that by 1900 the populations of many species were greatly reduced. At present, the importation of bird of paradise feathers into the United States and most of Europe is illegal. However, bird of paradise feathers and skins continue to be of great cultural importance for the indigenous highlanders of New Guinea, who use the feathers in head-dresses and other decorations.

Six of 24 species of New Guinea birds thought to require urgent conservation action are birds of paradise. To conserve the birds of paradise of New Guinea, a network of large rainforest reserves must be designated. The network of protected areas should be designed to include large areas of the habitat of all New Guinea birds of paradise. The reserves would also provide habitat for many other rare species of New Guinea wildlife. If these reserves are to be successfully established, they must be managed in a manner that also provides sustainable livelihoods for the indigenous people of the area. One of the great challenges of the future will be to balance human development with environmental conservation.

Resources

BOOKS

Beehler, Bruce M. A Naturalist in New Guinea. Austin, TX: University of Texas Press, 1991.

Beehler, Bruce M., Thane K. Pratt, and Dale A. Zimmerman. Birds of New Guinea. Princeton, NJ: Princeton University Press, 1986.

Frith, C.B. and B.M. Beehler. The Birds of Paradise: Paradisaeidae. Oxford University Press, 1998.

Raven, Peter, R. F. Evert, and Susan Eichhorn. Biology of Plants. 7th ed. New York: W.H. Freeman, 2005.

PERIODICALS

Beehler, Bruce M. The Birds of Paradise. Scientific American 261 (December 1989): 116-123.

Amy Kenyon-Campbell

Birds of Paradise

views updated Jun 11 2018

Birds of paradise

The birds of paradise are some of the most fascinating birds in the world. This is due to the striking coloration of the males of most species , and the wide range of behaviors demonstrated in the group. Researchers of animal behavior are particularly interested in the elaborate mating displays performed by male birds of paradise.

Birds of paradise are members of the family Paradisaeidae, which probably evolved on the island of New Guinea. The family is comprised of 43 species, 38 of which are found mainly or entirely on New Guinea. Two species are found only in the Moluccan Islands to the west of New Guinea, and four others are found mainly or entirely in northeastern Australia . Included within the family are such birds as astrapias, manucodes, paradisaeas, parotias, riflebirds, and sicklebills.


Description

The birds of paradise have a crow-like body shape, with strong feet and bill. However, in some species this basic pattern has been modified substantially. For example, the sicklebills have evolved a long, curved beak used to probe for insects in thick moss and tree bark . In many species the plumage of the males is modified with fantastic plumes, streamers, and wiry head and tail extensions. Although the body of most of the birds of paradise is 10-17 in (25-45 cm) long, the head plumes may reach 16 in (40 cm) in length, and the tail feathers up to 27 in (70 cm) long.

The females of most species are colored drab buff to black, with patterning that helps them remain hidden in the forest canopy while sitting on a nest. (This type of coloration is called cryptic.) Nests of most species are cup-shaped, and are built in forks of trees using leaves, twigs, and other plant material. Females lay one or two eggs, which average 1.4 in (37 mm) long and 1 in (26 mm) wide. Incubation periods are 17-21 days, and young birds remain in the nest 17-30 days.


Habitat and diet

New Guinea is an extremely mountainous island. Its equatorial location results in a tropical climate near sea level , but cooler conditions higher in the mountains . In fact, the highest peaks have glaciers present. In addition, the prevailing oceanic winds carry moisture-laden air over the island, resulting in as much as 27 ft (8.5 m) of rain per year in some places. Sites on the lee side of mountains, however, may be quite dry. The great variations of climate in New Guinea result in numerous different habitats occurring. The various species of birds of paradise are rather specific to particular kinds of habitat . For example, the crested bird of paradise is only found in upper montane forest and subalpine shrubland, while the trumpet manucode is found only in lowland and lower mountain forests , and the blue bird of paradise prefers mid-montane forest.

In addition to inhabiting different ecological zones in New Guinea, the various birds of paradise use different food resources. The two basic kinds of foods eaten are fruits and insects. There are also two groups of fruits: simple fruits rich in carbohydrate , such as figs, and complex fruits with high levels of fat and protein, such as those of mahogany and nutmeg . Species of birds of paradise tend to eat mainly simple fruits (e.g., the trumpet manucode), mainly complex fruits (e.g., the raggiana bird of paradise), or complex fruits plus significant quantities of insects (e.g., the magnificent bird of paradise).

When animals eat tree fruits, they may also digest the seeds , or the seeds may pass through the digestive system intact. If seeds are not digested, a tree seedling may sprout from them, helping the forest regenerate. In most forest habitats worldwide, the main fruit-dispersing animals are mammals . In New Guinea, however, this role is largely played by birds of paradise, which eat fruits and distribute the seeds, helping to ensure the dispersal of important species of forest trees.


Mating behavior

Polygynous birds of paradise

As mentioned above, many species of birds of paradise are sexually dimorphic, meaning the males and females have different appearances. The males have elaborate plumage patterns, which are used in their mating displays. The females of these species are drab and cryptic. Sexually dimorphic species are usually also polygynous, meaning the males may mate with more than one female. To attract a female, a male may perform a mating dance on the ground while conspicuously displaying its bright plumage and calling loudly, or it may display while perched on a shrub, or while hanging upside down on a tree branch. Males may perform these displays alone, or in competitive groups in a place called a lek. The females watch the displays and choose which male to mate with. The female choice appears to be based on the vigor of the display of the male, and the condition and color of his feathers. By choosing a vigorous mate, the female presumably ensures that her offspring will also be relatively healthy. Therefore, the strongest, most brightly-feathered males have a better chance of being chosen as a mate by females, while less attractive males may be passed over. The elaborate plumage of the males is thought to have evolved through this evolutionary process of sexual selection (i.e., females choosing mates on the basis of their desirable behavioral and anatomic traits, including color). After mating, the female returns to her nest and raises her offspring alone.

Researchers have noticed a relationship between the mating system and diet in the birds of paradise. Polygynous bird of paradise species that display in leks (such as the raggiana bird of paradise) tend also to eat mainly complex fruits. This is thought to be because females searching for these fruits fly long distances in the forest, and thus are likely to encounter groups of males displaying together. Polygynous species in which solitary males display (such as the magnificent bird of paradise) tend to eat insects plus complex fruits. To get insects, females need not fly long distances, so a male is more likely to be seen and chosen as a mate if he displays alone near the small home range of the female.

Interestingly, the polygynous birds of paradise also show sexual bimaturism. This means that males and females become sexually mature at different ages. Females of these species are thought to begin to breed when 2-3 years old, while males do not acquire mature plumage (and do not breed) until age 4-7 years. However, males of these species will grow adult plumage at a younger age when kept alone in captivity. This suggests that the delay in male maturation in the wild is due to hormonal suppression related to the presence of already-mature adult males.


Monogamous birds of paradise

Nine species of birds of paradise, including the manucodes, are sexually monomorphic. The males and females have coloring that is the same or nearly so (they tend to be brown or black), and both lack the elaborate plumage that characterizes most other birds of paradise. These species are monogamous, meaning the males and females mate with only one partner at a time, and in some species pair for life. As in most monogamous species, the males help the females raise the young.

These species typically feed mainly on simple fruits, such as figs. This type of fruit is relatively low in nutrients , compared to complex fruits and insects. Scientists think that the monogamous mating system may have developed in these species because two parents are necessary to provide enough nutrition to raise the young. Thus, in the birds of paradise, it appears that the diet of a species has influenced the evolution of its social system.


Habitat loss

Although much of New Guinea is still covered with rainforest , extensive areas are being logged or converted to agriculture. Moreover, because of population growth and economic development the habitat destruction by deforestation will increase in the future. Some species of birds of paradise are found in highly limited ranges, so deforestation of their local habitat could result in their extinction . Other species are found throughout New Guinea, but only within a particular altitudinal range. For example, the blue bird of paradise occurs only between 4,200 and 5,900 ft (1,300-1,800 m). This species is under pressure from habitat loss associated with human colonization at these altitudes.

In addition to habitat loss, many species are threatened by overhunting. After Europeans discovered the birds, the demand for their plumage to use as decoration increased, so that by 1900 the populations of many species were greatly reduced. At present, the importation of bird of paradise feathers into the United States and most of Europe is illegal. However, bird of paradise feathers and skins continue to be of great cultural importance for the indigenous highlanders of New Guinea, who use the feathers in headdresses and other decorations.

Six of 24 species of New Guinea birds thought to require urgent conservation action are birds of paradise. To conserve the birds of paradise of New Guinea, a network of large rainforest reserves must be designated. The network of protected areas should be designed to include large areas of the habitat of all New Guinea birds of paradise. The reserves would also provide habitat for many other rare species of New Guinea wildlife . If these reserves are to be successfully established, they must be managed in a manner that also provides sustainable livelihoods for the indigenous people of the area. One of the great challenges of the future will be to balance human development with environmental conservation.

Resources

books

Beehler, Bruce M. A Naturalist in New Guinea. Austin, TX: University of Texas Press, 1991.

Beehler, Bruce M., Thane K. Pratt, and Dale A. Zimmerman. Birds of New Guinea. Princeton, NJ: Princeton University Press, 1986.

Frith, C.B., and B.M. Beehler. The Birds of Paradise: Paradisaeidae. Oxford University Press, 1998.

Perrins, C.M., and A.L.A. Middleton, eds. The Encyclopedia ofBirds. New York: Facts on File, 1985.

Raven, Peter, R. F. Evert, and Susan Eichhorn. Biology ofPlants. 6th ed. New York: Worth Publishers Inc., 1998.


periodicals

Beehler, Bruce M. "The Birds of Paradise." Scientific American 261 (December 1989): 116-123.


Amy Kenyon-Campbell

KEY TERMS

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Cryptic

—Drab, usually brownish coloration that makes an organism difficult to see in its natural habitat and allows it to hide from predators.

Lek

—A central area in which many males of a species perform mating displays simultaneously.

Montane

—Habitat on relatively cool, moist mountain slopes below the tree line.

Sexual bimaturism

—A condition in which the males and females of a species become sexually mature at different ages.

Sexual dimorphism

—The occurrence of marked differences in coloration, size, or shape between males and females of the same species.

Subalpine

—Habitat on high mountain slopes, above the treeline.

Paradisaeidae

views updated May 11 2018

Paradisaeidae (birds of paradise; class Aves, order Passeriformes) A family of small to medium-sized birds which have brightly coloured, iridescent plumage and elaborate plumes on the head, back, wings, and tail; some also have wattles. Females tend to be dull-coloured. The bill is short to long, straight and slender, and highly decurved or hooked. The wings are short and rounded, the tail short and square to long and graduated. The birds are arboreal, feed on insects, frogs, lizards, fruit, and seeds, and nest in a cavity or tree fork. Their plumes are used in highly elaborate displays which also involve unusual vocal sounds. There are 20 genera, with 43 species, found mainly in New Guinea, but also in Australia and the Moluccas.

birds of paradise

views updated Jun 11 2018

birds of paradise See PARADISAEIDAE.