Bowerbirds: Bowers, Types, Decorations, Courtship Displays | Sea Life, Islands and Oceania

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BOWERBIRDS

From “Birds of New Guinea: Second Edition (Princeton Field Guides)
by Thane K Pratt , Bruce M Beehler (2014) Amazon

Bowerbirds are stocky, stout-billed bird known for their unusual behavior. Male bowerbirds construct house-like "bowers" to attract females. Bowerbirds, especially females, are rather drab-looking birds. Some have some coloration which they only show during displays. Males of some species are more brightly colored than females and are very promiscuous. One scientist observed a male mate with five females and try to woo ten others.

Bowerbirds are about the size of pigeons and are found only on New Guinea — both Papua New Guinea and Papua and West Papua in Indonesia — and in Australia. Bowerbirds are are found in many of the same places as birds of paradise. Instead of using their feathers for elaborate courtship displays they use objects. A bower is a special construction of twigs used to display these objects. Bowerbirds are considered. Most songbirds have nine to 10 secondary feathers, bowerbirds have more, ranging from 11 to 14. They also have larger lacrimal bones, a trait shared by lyrebirds (Menuridae). Their legs and feet are short, strong, and covered in scales. [Source: Aqua Nara Dakota, Animal Diversity Web (ADW) |=|]

Bowerbirds make up the bird family Ptilonorhynchidae. The family has 27 species in eight genera of which about 20 are recognized as bowerbird. They are medium to large-sized passerines (perching birds). The smallest is the golden bowerbird, which is 22 centimeters (8.7 inches) long and weighs 70 grams (2.5 ounces). The largest is the great bowerbird, which is 40 centimeters (16 inches) long and weighs 230 grams (8.1 ounces). Their diet consists mainly of fruit but may also include insects (especially for nestlings), flowers, nectar and leaves in some species. Satin and spotted bowerbirds are sometimes considered agricultural pests due to their habit of feeding on introduced fruit and vegetable crops and have occasionally been killed orchard owners. [Source: Wikipedia]

About half of bowerbird species are endemic to New Guinea; eight are endemic to Australia, and two found in both. Bowerbird are found mainly in tropical regions of New Guinea and northern Australia, with some species extend into central, western, and southeastern Australia. They occupy a range of different habitats, including rainforest, eucalyptus and acacia forest, and shrublands. Bowerbirds have the longest life expectancy of any passerine family bird. The two most banded and studied species, the green catbird and satin bowerbird have life expectancies of around eight to ten years. One one satin bowerbird lived to the age of 26.

Bowerbird Behavior and Communication

From “Birds of New Guinea: Second Edition (Princeton Field Guides)
by Thane K Pratt , Bruce M Beehler (2014) Amazon

The complex mating behaviour of bowerbirds, with their highly specialized of valued objects, colors of decorations, has led some researchers to regard the bowerbirds as among the most behaviorally complex species of bird. They also provide good evidence to back up theories that sexual selection has been powerful mechanism in animal evolution. Charles Darwin discussed bowerbirds as well as birds-of-paradise in his writings.

Bowerbird are superb vocal mimics. MacGregor's bowerbirds has been observed imitating pigs, waterfalls, and human chatter. Satin bowerbirds commonly mimic other local species as part of their courtship display.

On spotted bowerbirds, Virginia Morell wrote in National Geographic: A “male, a blue-jay-size bird colored beige and brown, squawks at us from a nearby eucalyptus tree. He rasps out a long series of skraas, then changes to the snarling, spitting sound of a cornered cat, and ends with a laughing call that sounds like a kookaburra. "He's trying to scare us," Dr. Gerald Borgia, a biologist at the University of Maryland, says. "They're great imitators — cats, hawks, kids crying. They use that skraa call in their courtship displays too, so there must be something about it that allows females to find genetically superior males.” [Source: Virginia Morell, National Geographic, July 2003]

Bowerbird Mating and Reproduction

Bowerbirds engage in extraordinarily complex courtship and mating behaviour, where males build a bower to attract mates. Males of all but three species are polygynous, meaning that they try to mate with as many females as possible. In some species, one male can mate with as many as twenty females in a single season, while the majority fail to mate at all. [Source: J. Albert C. Uy, Natural History magazine, March 2002]

Ailuroedus catbirds are monogamous, with males raising chicks with their partners, but all other bowerbirds are polygynous, with the female building the nest and raising the young alone. Female bowerbirds build a nest by laying soft materials, such as leaves, ferns, and vine tendrils, on top of a loose foundation of sticks. [Source: Wikipedia]

Phylogenetic analyses of genomic data of the three main bowerbird groups: A) avenue-building species,B) maypole-building species, and C) monogamous species, From: Ericson et al (2020) Systematic Biology

All Papuan bowerbirds lay one egg, while Australian species lay one to three with laying intervals of two days. Bowerbird eggs are around twice the weight of those of most passerines of similar size. The eggs of satin bowerbirds weigh around 19 grams (0.67 ounces). Eggs hatch after 19 to 24 days, depending on the species. The eggs of catbirds and tooth-billed bowerbirds are plain cream in color those of other species have brownish wavy lines.

The high degree of choosiness by females in their selection of mates and the high degree of mating success of just a few males with quality displays and bowers — viewed by some as an indicator of a high degree of intelligence — suggests that females gain important benefits from mate choice. Since males have no role in parental care and give nothing to females except sperm, it is suggested that females gain genetic benefits from their mate choice. But his is just a theory at this point as it is difficult to observe bowerbirds in the wild and find evidence to back this It has also been suggested that there is an inverse relationship between bower complexity and the brightness of plumage, based on the fact that some of the most elaborate bowers are constructed by the drabbest bowerbirds, but this hypothesis is not well supported because a wide range of bower types are built by birds with similar plumage.

Bowerbird Bowers

In nearly every species of bowerbird, males try to impress females by building elaborate structures called bowers — long, twiggy or grassy corridors that open to a courtyard decorated with small objects. Ailuroedus catbirds are the only species which do not construct either bowers or display courts. Some bowers are quite elaborate. Other are not Toothed bill bowerbirds of the rain forest of northeast Australia simply clear an area on the forest floor and cuts some large leaves and place them in the clearing.

J. Albert C. Uy wrote in Natural History magazine: Bower design and decoration are specific to each kind of bowerbird. For example, the satin bowerbird, which inhabits the dry woodlands of eastern Australia, erects two parallel walls of sticks on top of a circular platform, also made of sticks. The walls flank a path that visiting females step onto.Adorning the platform in front of the path are objects such as assorted blue parrot feathers, white snail shells, and yellow and purple blossoms from wild tobacco. Other species of bowerbirds build towers; some simply clear leaf litter from the ground to form a court where the male dances for visiting females. In their own way, most bowerbirds are skilled architects, but none can rival the plain brown Vogelkop. [Source: J. Albert C. Uy, Natural History magazine, March 2002]

The bower does not serve as the traditional secure nest for eggs and young. It is instead a piece of statement architecture designed solely to attract females. Among the bowerbirds, the male’s construction of display architecture is the defining courtship behavior. He uses a range of techniques to build a lavishly decorated bower from sticks, plants, and a vast range of decorative materials. This, together with vigorous dance movements and complex songs, is designed to attract as many females as possible. As far as the architecture is concerned, display is all. Once she has mated, a female will fly off alone to build a more traditional piece of nest architecture, a cup nest, in which to raise her young.

Dr. Gerald Borgia believes there are at least five reasons for the building of a bower: 1) In some cases, it functions as a device to attract females; 2) it has an important role in controlling a male’s display so the female can observe it from a comfortable position; 3) it provides a stage for the male’s performance; 4) it helps orient the female; 5) once inside the bower, it orients her to maximize the appeal of the male’s display. In any population, there are only a few eligible males, so they get to mate with many females. Ostentatious architecture has the advantage over eye-catching plumage because it is separate from the bird, making him less conspicuous to predators. But it does not guarantee success. It takes years of practice for a male to become a successful builder of bowers, and younger architects might fail to attract a single visitor.

Types of Bowerbird Bowers

Bowerbird bowers generally fall into two types: 1) avenue bowers, built with two parallel walls of sticks forming a tunnel, and 2) maypole bowers, constructed by weaving sticks around a central sapling. Some species create simpler mat bowers consisting of a decorated platform of leaves or moss. Some species, like the Lauterbach's Bowerbird (Yellow-breasted Bowerbird), build unique bowers with four walls and cross passages. [Source: Google AI, Wikipedia]

The bowerbird genuses Prionodura, Amblyornis, Scenopoeetes and Archiboldia bowerbirds build maypole bowers. These bowers feature sticks woven around a central sapling, creating a central column that can sometimes have a hut-like roof. Some of these bowers look like grass-roof huts or wigwams. Golden bowerbirds and streaked bowerbirds are examples of species that build maypole bowers.

The bowerbird genuses Chlamydera, Sericulus and Ptilonorhynchus build avenue-type bowers. These are built as two parallel walls of vertically placed sticks, forming a walkway or tunnel for the male to display. These are often a platform of small sticks laid side by side and contain a curving, tunnel-like rood make with curved twigs stuck in the ground. Satin bowerbirds and flame bowerbirds construct avenue bowers.

Mat bowers are a decorated platform made of leaves or moss, rather than an elaborate stick structure. Tooth-billed bowerbirds and Archbold's bowerbirds create mat bowers. The catbird genus, which includes green catbirds and Northern catbirds, are the only bowerbirds that do not construct either bowers or display courts.

Bowerbird Courtyards

The main area of attention is some bowerbird bower’s a platform in front of a path with objects such as assorted blue parrot feathers, white snail shells, and yellow and purple blossoms from wild tobacco often in carefully-placed arrangements. Some species of bowerbirds clear leaf litter from the ground to form a courtyard where the male dances for visiting females. [Source: J. Albert C. Uy, Natural History magazine, March 2002]

Gray and white bones, shells, and pebbles decorate most great bowerbirds’ courtyards. But researchers have also found bottle caps and plastic figurines there — items apparently discarded in the forest. A single courtyard may contain as many as 5,000 carefully arranged objects.

Virginia Morell wrote in National Geographic: Under old peppertrees, thornbushes, and stands of oleanders, male spotted bowerbirds have they've built elaborate U-shaped arenas of dried grasses, 12 to 14 inches (30.5 to 35.6 centimeters) high and 12 to 20 inches (30.5 to 50.8 centimeters) long. They've decorated them with piles of sun-bleached sheep vertebrae, shiny aluminum foil, pop-tops from beer cans, shards of broken windshield glass, and little strips of red and blue plastic. The fanciest bowers feature special, seductive tidbits: a silver fork, the shoe token from a Monopoly game, old gun shell casings, red, blue, and purple glass of the deepest hues. [Source: Virginia Morell, National Geographic, July 2003]

The birds have arranged their treasures with an eye to the light — how does that bone pile look when the morning sun hits it? — and to their symmetry: silver metal hoops of unknown origin, for example, placed at equal distances from opposite ends of the bower. Now a male can do little more than watch and wait. If he's built a good bower, then he'll succeed in life's ultimate contest and win the top prize: a female who chooses him as a mate.

Decorating Bowerbird Bowers and Courtyards

In and around the bower, male bowerbirds place a variety of brightly colored objects he has collected. The objects can include shells, blossoms and land snails. Some bowerbirds have a strong preference for blue objects. One bird decorated his bower with two dozen blue objects including a marble, a shotgun shell, a toothbrush, a toy plane, a pencil sharpener and two dozen blue clothespins.↨

Male bowerbirds have decorated their bowers with butterfly wings, seeds, fungi, birds of paradise feathers, beetle carapaces, ballpoint pens, bits of charcoal, bracelets, toothbrushes, anything it can find. Satin bowerbird males "paints" their bowers by crushing fruit in their bill and then spreading the bright-colored juice using their bill as if it were a paintbrush.

The objects are usually different among each species and may include hundreds of shells, leaves, flowers, feathers, stones, berries, and even coins, nails, and pieces of glass. The males spend hours arranging their collections of objects. Bowers within a species share a general form but do show significant variation, and the collection of objects reflects the biases of males of each species and their ability to procure items from their surroundings, often stealing them from neighboring bowers. Several studies of different species have shown that colors of decorations males use on their bowers match the preferences of females.

Constructing and Decorating a Bowerbird Bowers

With meticulous care male bowerbirds construct "bowers" with high walls up to 30 centimeters (one foot) high, enclosing a 10-centimeters (four-inch) -wide alley where the male hopes to lure a female. The walls are typically oriented north to south. One ornithologist shifted the position of the walls only to have another bowerbird place them back the way the were before.↨

Bowerbird extend a great deal of energy and labor making and maintaining their bowers. Some spend nearly the entire day collecting objects and making sure everything is in order. They also have to keep an eye out for other birds to make sure they don’t steal their stuff. Male bowerbirds typically live 30 years and begins collecting objects for their courtyards by age five. When a male finish his work he may call from a nearby tree, telling females to come and have a look.

Virginia Morell wrote in National Geographic: A male can build a straw bower in the space of a few days. Decorating it, however, takes several additional days, and getting the ornaments in the right place can take years. Spotted bowerbirds build their bowers anew each year, usually locating them close to those of the preceding mating season. And when an older bird dies, a younger one — perhaps a son or other close male relative — takes over his locality and his treasures. "All these decorations, what the males choose and how they place them, is driven by female choice," Borgia says. "In a small way, they're like us: The male's ornaments aren't necessarily a physical part of him, but are more in the things he acquires." Source: Virginia Morell, National Geographic, July 2003]

"That's really what it comes down to," says Gerry Borgia, who studied the mating behaviors of bowerbirds for decades. "So you wonder sometimes when you see poorly built bowers," he says, pointing to one in disarray. "You want to say to the guy: 'Hey! This is about your reproductive success! Get moving! Straighten those straws! Find some more bones! Why be a C student?'" Borgia shakes his head like a teacher who can't figure out why some kid who has everything handed to him on a platter would still choose to fail. "He's probably not getting any cops [copulations] this year," the professor says, assigning the bird to possible evolutionary oblivion.

"You watch enough of these cops, and you begin to get a feel for why the female chooses one male and not another," he explains. "It's my guess that this guy isn't going to do well. I mean, that's pathetic," he says, waving his hand at the bird's puny pile of vertebrae. "And the thing is, he took over this site from an older male who died, but who had a great bower with lots of bones. And they're still here! This new guy just hasn't made the effort to move them to his bower."

Bowerbird Optical Illusions

Some bowerbrids arrange rocks from smallest to largest in their court area to create an illusion that makes the male standing among the smaller rocks look bigger and more inviting to a female standing on the larger rock side. Mindy Weisberger wrote in Live Science: The geometry of the courtship site creates an illusion of uniformity: When a female bowerbird views the court from within the avenue, all of the court objects appear to be the same size. In a 2012 study, published in the journal Proceedings for the National Academy of Sciences, researchers described how male bowerbirds arranged their court area in such a way that when the male bird stands in front of it, he appears larger and more imposing to the female viewing him from outside. [Source: Mindy Weisberger, Live Science, February 14, 2023]

The research was done by evolutionary ecologist John Endler of Deakin University in Australia. Kat McGowan wrote in Discover magazine: Endler realized the wooer uses a trick called forced perspective. The birds arrange objects by size, so the smallest are closest to the entrance and larger pieces farther away. From the female’s point of view inside the corridor, the bigger, more distant items look about the same size as the nearby smaller ones. The courtyard may appear smaller, potentially making the male seem larger to deliberating females. Photographers regularly use the same trick. If you stand some distance from the Leaning Tower of Pisa, a friend can take a picture that looks as if you are propping up the tower. Creating this illusion is a priority for great bowerbirds. When Endler rearranged their objects, they put their courtyards back in order within three days. [Source: Kat McGowan, Discover magazine, July 11, 2012]

Endler also described another possible motive for the illusion: mesmerizing the female. He found that the longer she stays to watch the male in his courtyard, the more likely she is to mate with him. Endler’s hunch is that as the male darts around waving a trinket in his beak, the bauble seems to change size against the backdrop. Fascinated, the female lingers to look — and her choice is made.

Male Bowerbird Courtship Displays

In addition to the bower construction and ornamentation, male birds perform courtship displays to attract females. Research suggests males adjust their performance based on success and female response. The displays often involve complex dances. Males strategically arrange brightly colored objects, and their courtship often includes intricate vocalizations and the offering of food to demonstrate their skills and ability to provide for a nest. The female judges the quality of the bower and the male's display, with the most well-constructed and decorated bowers correlating with higher mating success for the male.

Objects in bowerbird’s court such as fruits, flowers, stones, shells, and sometimes human-made items like plastic bottle caps or even rings, with a preference for certain colors, may be used in the display. The decorations are often arranged in particular patterns to attract female attention. While the female watches from within the bower, the male presents himself and his decorations by holding objects in his beak or gesturing with them at the bower entrance.

Males perform intricate dances as part of their display to impress females. Bower geometry and decorations can influence the sound of the male's vocalizations, increasing the intensity of certain frequencies at specific display positions. Offering food items like fruits or fish shows the male's hunting skills and his potential capacity to provide for a mate, which is a common courtship ritual across many bird species.

Males wait of a curious female to enters their courtyards and when they do they hold and wave around a trinket. If the female lingers, he will approach and try to mate. Kat McGowan wrote in Discover magazine: When a female arrives, she enters the corridor and inspects the male’s work. He sneaks around the side of the bower, waving a brightly colored item such as a shell or a bit of plastic in his beak in hopes of holding her interest. [Source: Kat McGowan, Discover magazine, July 11, 2012]

Choosy Bowerbird Females

Females searching for a mate commonly visit multiple bowers, often returning to preferred one several times, and watching males perform their elaborate courtship displays and also inspecting the quality of their bowers. Through this process female reduce the set of potential mates. Females show a preference for males with more elaborate, well-constructed, and highly decorated bowers — supporting the "marker hypothesis" which says bowers provide information about the male's health and DNA quality. Many females end up selecting the same male, and many under-performing males are left without copulations (cops). Females mated with top-mating males tend to return to the male the next year and search less.

Virginia Morell wrote in National Geographic: Male and female spotted bowerbird look very much alike — brownish and speckled with golden dots, a spray of bubble-gum-pink feathers on the back of their necks. These are usually hidden from view, but males and females unfurl them in times of aggression, and the male also fans them out when courting a female or when practicing his mating show. [Source: Virginia Morell, National Geographic, July 2003]

Young females may make multiple visits to several bowers, studying them and the males, learning, Borgia thinks, how to choose. They get nothing from the male beyond his genes; he does not help to raise the chicks. Nor do females appear to mate with more than one male in one season. "She studies them and makes a choice," says Borgia, "and if she's happy, she'll return to the same male the next year."

The female's desire to forage for fruits of a certain color seems to be exploited by males decorating their bowers. In a study by Madden and Tanner (2003), grapes of different colors were used to determine preferences. Male regents bowerbird preference for blue decorations was found to be correlated with female preference for eating blue grapes. This correlation seems to be common among bowerbird species, with different species favoring different colors. The fruits used as decorations aren't eaten by the male, but sometimes the female takes them away or eats them. The amounts and colors of fruit present help determine a male's mating success. [Source: Aqua Nara Dakota, Animal Diversity Web (ADW) |=|]

Long Wait for Male Bowerbirds

Virginia Morell wrote in National Geographic: The most successful males are about ten years old and have spent some five lonely bachelor years perfecting their skills. In this species (as with most birds), a male can't force a female to mate. Like a solo rock star, he must devise a bower, song, and dance that wows the gals. [Source: Virginia Morell, National Geographic, July 2003]

I set up a blind close to the bower of one of Borgia's spotted bowerbirds, a male the scientist says was the "big scorer" the previous year. Borgia has named each bird for the location of its bower. This top bird has built its mating arena in the shade of two old peppertrees on the Gerar Station, and so is dubbed "Gerar Pepper Bower." I nickname him "G.P." G.P.'s bower is a sturdy, handsome structure, its decorations artfully arranged, its straw walls thick and symmetrical. In the center he has piled shattered bits of windshield glass, each piece about a half inch (1.27 centimeters) in diameter. When the sun hits them, they glitter like diamonds. He's hung some bits of metal wire and a strip of red plastic along the bower's walls and stacked a long, thick wall of sheep vertebrae just beyond one end. At the opposite end lies an equally large pile of clear and colored glass, sprinkled with a few shell casings and aluminum pop-tops. Other smaller piles of glass and odd pieces of aluminum foil and plastic lie scattered in a mosaic pattern around the bower, some as far away as four feet (1.2 meters). "Oh yes, all that is part of his display," Borgia says, when I ask about some seemingly random bits of glass. "Everything here that's not natural is part of his bower."

I saw many such practice runs over the next four days. Sometimes G.P. perched on a branch beside his bower and rehearsed his screechy love songs, which resembled the harsh blast of steam from a cappuccino machine. Sometimes he walked the short length of his straw bower, licking every individual straw to leave behind traces of his saliva. Or he would rearrange a pop-top here, a plastic ring there, or drop one of his shell casings on the pile of glass, then cock his head to listen to the pretty ching it made. I imagined he would like to make that sound for a female. Sometimes one or two other males arrived to check out the competition or to try to steal one of G.P.'s objets d'art. But he was vigorous in defense of his bower and belongings, and flew at them with beak and tongue out, claws ready to strike.

One afternoon, after another long, lonely day, G.P. picked up a bunch of green pepper berries, fluffed up his pink topnotch, and raced around and through his bower, screeching and clucking and looking rather ridiculous, like any poor soul waiting for the phone to ring. Alas, I was the only female in view Were none of the females watching G.P. pleased enough? Or was it merely a slow period in the season? The wind blew steadily most afternoons, and G.P. often flew away when it started to kick up, apparently deciding it wasn't worth his time to wait.

And then, on the fourth morning, a female appeared. She perched on the branch beside the bower for a minute, then hopped right inside. G.P. went berserk, squawking and fluffing and racing around his bower. He stopped at one end and picked up a pop-top to show her, then dropped it and did another lap around the bower. She just watched. Then she began to lower herself, ever so slightly lifting her tail, tipping her head forward. Borgia had told me that was the "choice" sign, and I held my breath. G.P. screeched even louder and hopped toward her. And at that very instant, another male appeared. Romance gave way to a brawl, and the female flew away. But I was sure she had made her choice. She would be back, and G.P. would get another chance to keep his genes at play in the game of life.

Image Sources: Wikimedia Commons

Text Sources: Animal Diversity Web animaldiversity.org , National Geographic, Live Science, Natural History magazine, Australian Museum, David Attenborough books, Australia Geographic, New York Times, Washington Post, Los Angeles Times, Smithsonian magazine, Discover magazine, The Conversation, The New Yorker, Time, BBC, CNN, Reuters, Associated Press, AFP, Lonely Planet Guides, Wikipedia, The Guardian, Top Secret Animal Attack Files website and various books and other publications.

Last updated August 2025