Animals City birds use handcuffs for courtship
Male bowerbirds in Australia are increasingly relying on found objects made by humans to find mates. A study shows how strongly urbanization influences the animals' love lives.
04.06.2026, 04:59
SDA
Wires, broken glass, cans - and even handcuffs: Male bowerbirds in Australian cities are increasingly decorating their mating grounds with discarded objects to impress females. Instead of relying on natural decorations such as leaves, seeds or fruit as they once did, the birds are also resorting to a colorful hodgepodge of human waste and everyday objects, as a study by the University of Exeter shows.
Bowerbirds - scientifically known as Ptilonorhynchidae - are songbirds that are only native to Australia and New Guinea. They are world-famous for their unique courtship behavior, with the males building elaborate constructions of twigs on the ground. These are then elaborately decorated to attract females.
For the study published in the journal "Royal Society Open Science", researchers compared the collections of dozens of bowerbirds in the city of Townsville in the state of Queensland with those of their conspecifics in the countryside. The result: city birds used significantly more and more colorful objects, mostly of human origin.
Which finds are particularly popular?
Green glass splinters and red wires were particularly popular. However, the researchers also found unusual objects such as handcuffs, medicine bottles near a hospital or fluorescent face masks from the vicinity of a sports stadium. One particularly industrious male had collected more than 300 items. Rural rivals were content with an average of around 20 decorations, while urban birds managed around 90.
Courtship follows a sophisticated ritual: as soon as a female enters the bower, the male throws individual objects into her field of vision and presents his plumage at the same time. Bowerbirds have much more sensitive color vision than humans.
Land birds also like garbage
Another experiment also showed the animals' preference for colorful human objects. Both urban and rural birds preferred artificial objects to natural materials such as leaves, seeds or fruit. Whether the preference for man-made objects has a positive or negative effect on the birds in the long term remains to be seen.
It is also still unclear whether the more conspicuous decorations actually increase the chances of finding a mate. "Our study did not investigate whether females prefer the more conspicuous items that are collected in urban areas," said Caitlin Evans, a scientist involved in the study. "But the males' enthusiasm for collecting these items suggests that they do."
