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Bowerbird
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This article is about the species of bird called bowerbird. For the band, see Bowerbirds (band).
Bowerbirds and catbirds make up the bird family Ptilonorhynchidae. The family has 20 species in eight genera. All are medium-sized passerines, ranging from the Golden Bowerbird (22 cm and 70 grams) to the Great Bowerbird (40 cm and 230 grams). Although their distribution is centered around the tropical northern part of Australia-New Guinea, some species extend into the central Australian desert and the cold mountainous regions of southeast Australia.
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Encyclopedia
This article is about the species of bird called bowerbird. For the band, see Bowerbirds (band).
Bowerbirds and catbirds make up the bird family Ptilonorhynchidae. The family has 20 species in eight genera. All are medium-sized passerines, ranging from the Golden Bowerbird (22 cm and 70 grams) to the Great Bowerbird (40 cm and 230 grams). Although their distribution is centered around the tropical northern part of Australia-New Guinea, some species extend into the central Australian desert and the cold mountainous regions of southeast Australia. The diet of bowerbirds consists predominantly of fruit, but may also include insects, flowers, and leaves in some species.
Note that the Gray Catbird (Dumetella carolinensis) and Black Catbird (Melanoptila glabrirostris) from the Americas and the Abyssinian Catbird (Parophasma galinieri) from Africa are unrelated birds that belong to different families.
Distribution and habitat
The bowerbirds have an Austro-Papuan distribution, with ten species being endemic to New Guinea, eight species being endemic to Australia and two species being found in both. They occupy a range of different habitats, including rainforest, eucalypt and acacia forest and woodland and shrublands.
Mating behaviour
The catbirds are monogamous and raise chicks together, but all other bowerbirds are polygynous, with the female building the nest and raising the young alone. These latter species are sexually dimorphic, with the female being drab in color. Bowerbirds build nest by laying soft materials, such as leaves, ferns, and vine tendrils on top of a loose foundation of sticks. They lay one or two eggs, which hatch after 19 to 24 days, depending on species.
The most notable characteristic of bowerbirds is the extraordinarily complex behaviour of males, which is to build a bower to attract mates. Depending on the species, the bower ranges from a circle of cleared earth with a small pile of twigs in the center to a complex and highly decorated structure of sticks and leaves — usually shaped like a walkway, a small hut or a maypole — into and around which the male places a variety of objects he has collected. These objects — usually of a hue to which the male in question is particularly attracted — may include hundreds of shells, leaves, flowers, feathers, stones, berries, and even discarded plastic items or pieces of glass. The bird spends hours carefully sorting and arranging his collection, with each object in a specific place; if an object is moved while the bowerbird is away he will put it back in its place. No two bowers are the same, and the collection of objects reflects the personal taste of each bird and its ability to procure unusual and rare items (going as far as stealing them from neighboring bowers). At mating time, the female will go from bower to bower, watching as the male owner conducts an often elaborate mating ritual and inspecting the quality of the bower. Many females end up selecting the same male, and many under-performing males are left without mates.
In a striking example of what is known as the "transfer effect," bowerbird species that build the most elaborate bowers are dull in color and show little variation between male and female, whereas in bowerbird species with less elaborate bowers the males have bright plumage. Presumably, evolution has "transferred" the reproductive benefits of bright male plumage (common among polygamous birds) to elaborate bowers, allowing males to display their fitness by means other than physical characteristics that would appear to attract predation.
This complex mating behaviour, with highly valued types and colors, and decorations that, in many species, vary in attractiveness from year to year like fashion trends, has led some researchers to regard the bowerbirds as the most advanced of any species of bird. It also provides some of the most compelling evidence that the extended phenotype of a species can play a role in sexual selection and indeed act as a powerful mechanism to shape its evolution, as seems to be the case for humans.
In addition, many species of bowerbird are superb vocal mimics. Macgregor's Bowerbird, for example, has been observed imitating pigs, waterfalls, and human chatter.
Relationships
Though bowerbirds have traditionally been regarded as closely related to the birds of paradise, recent DNA-DNA hybridisation studies suggest that while both families are part of the great corvid radiation that took place in or near Australia-New Guinea, the bowerbirds are more distant from the birds of paradise than was once thought. Sibley's DNA-DNA hybridization studies placed them close to the lyrebirds; however, anatomical evidence appears to contradict this placement and the true relationship remains unclear.
Systematics
Genus Ailuroedus
Genus Scenopooetes
Genus Archboldia
Genus Amblyornis
Genus Prionodura
Genus Sericulus
Genus Ptilonorhynchus
Genus Chlamydera
External links
on the Internet Bird Collection
cartoon-style treatment of bower building.
- a virtual children's book by S.S. Sebastian about a bowerbird called Bramble that collects items for his bower. This virtual book is held by the State Library of Queensland, Australia.
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