Male Bowerbirds in Australian Cities Are Turning Human Trash Into Treasure to Impress Potential Mates

Even rural birds prefer human-made objects, such as colored glass and wire, when given the choice between them and natural decorations, like leaves and shells, according to a new study

Sara Hashemi | Daily Correspondent

June 17, 2026 11:35 a.m.

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To woo potential mates, male bowerbirds can spend months building and decorating elaborate structures on the ground called bowers. Rural birds tend to adorn their engineered masterpieces with items like leaves, fruits, flowers and snail shells.

Urban birds, on the other hand, seem to have a penchant for trash.

In a study published in the journal Royal Society Open Science on June 3, researchers looked at how urbanization has changed the way Australia’s great bowerbirds (Chlamydera nuchalis) display their affection. They found that city birds tend to deck out their bowers with larger, more colorful decorations—usually items left behind by humans. When given the chance, however, both urban and rural birds prefer human-made objects over natural ones.

Many animals have had to adapt their mating strategies because of human activity. Past research shows that some birds, frogs and insects have altered their mating calls to reduce overlap with anthropogenic noise. But relatively few studies have focused on sexual signals that aren’t sound-related.

So, the scientists behind the new work examined 61 bowers across two sites in northern Queensland—one in the rural Dreghorn Cattle Station and the other in urban Townsville City—during the birds’ 2023 breeding season. They photographed the bowers and nearby decorations with a filter and lighting meant to mimic a female bowerbird’s perspective, since the birds see ultraviolet light, as well as from the view of humans.

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Decorations on urban bowers were more than ten times more likely to be human-made objects than those on rural bowers, the team found. Still, “even in rural areas, birds find items made by humans,” says study co-author Caitlin Evans, a behavioral ecologist at the University of Exeter in England, in a statement.

The most common decorations in rural areas were green leaves, seeds and green glass, while urban bowers frequently featured green glass and red wire as decor. More unusual adornments included handcuffs, medicine jars at bowers near a hospital and mouthguards at locations near a sports field.

The researchers suspect that the birds steal decorations from one another’s bowers—and from people. “One family told us that they have to keep the garage door shut, otherwise bowerbirds fly into the garage and steal their really nice nails and screws,” Evans tells the New York Times’ Annie Roth.

Evans and her colleagues also collected ten items from each of the 30 urban and 24 rural bowers involved in an experimental portion of the study. Then, they left a mixed pile of ten urban and ten rural decorations near each bird’s structure. (Males were never presented with decorations from their own bower.)  

When the researchers returned to the sites three days later, they looked at which decorations were taken and which ones were left untouched by the birds. Overall, males were more than ten times more likely to select city bower decorations, the team found.

The birds may be drawn to human items because in species where bright colors serve as signals, new and unnatural colors can be especially attention-grabbing, says Daniel Baldassarre, a behavioral ecologist at the State University of New York at Oswego who was not involved in the study, to the Times. “They get excited by things that pop.”

Plastic and metal objects also don’t break down as easily as natural items, such as berries, and therefore don’t need to be replaced as often, which might contribute to their popularity, Evans tells the outlet.

It’s unclear how this inclination for human objects could be impacting the birds. In 2018, however, experts reported that male satin bowerbirds (Ptilonorhynchus violaceus) pick up plastic trash that could hurt them, like bottle rings.

“Unfortunately, nowadays with our satin bowerbirds, they like blue things, and there’s not much blue in nature. So, they collect artificial things, and they pose great risk to them,” said Tim Faulkner, an owner and director of the Australian Reptile Park, to the Australian Broadcasting Corporation’s Emma Siossian at the time.

The new study “demonstrates that the availability of human items—often glass and plastic—is affecting the behavior of bowerbirds,” says study co-author Laura Kelley, an animal behavior researcher at the University of Exeter, in the statement.

“We don’t yet know whether this has any negative or positive impact on them, but it’s a reminder of how human activity is changing the natural world in unanticipated ways.”

Sara Hashemi | Read More

Sara Hashemi is a science writer and fact-checker currently based in New York City. Her work has appeared in Sierra, The Body, Maisonneuve magazine and more.