Birds Guide

Bowerbirds
Male Satin Bowerbird.
Scientific classification
Kingdom: Animalia   Phylum: Chordata   Class: Aves   Order: Passeriformes   Family: Ptilonorhynchidae GR Gray, 1841
Genera
Many, see text

Bowerbirds and catbirds make up the family Ptilonorhynchidae. All are small to medium in size. 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 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 maytree -, into and around which the male places a variety of objects he has collected. These objects - always strikingly colored - may include hundreds of shells, leaves, flowers, feathers, stones, berries, and even discarded plastic items, pieces of glass or similar things. The bird will spend hours carefully sorting and arranging his collection, with each thing 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 capability 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. Inevitably, many females will end up selecting the same male, and many underperforming males will be 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 bowerbird species with minor bowers have males with 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 decorations varying in attractiveness from year to year like a fashion trend in many species, has led some researchers to regard the bowerbirds as the most advanced of any species of bird. It provides also one of the most compelling evidences 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 bowerbirds are superb vocal mimics. Macgregor's bowerbird, for example, has been observed imitating pigs, waterfalls, and even human chatter.

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 landmark DNA studies placed them close to the lyrebirds; however, anatomical evidence appears to contradict this and the true relationship remains unclear.

Species of Ptilonorhynchidae in taxonomic order

A Male Bowerbirds nest.

Bowerbird

Note that the Gray Catbird (Dumetella carolinensis) is an unrelated American bird that belongs to a different family.

External links

• PBS Nature: Bower Bird Blues
• PBS Nova: Flying Casanovas
• Bowerbird videos on the Internet Bird Collection