Male bowerbirds hope to surprise females with bright man-made objects

When the team returned to the sites, they identified the decorations that were picked from the mud pile and moved to the bower, and whether they came from rural or urban areas. After recording the data, all the original decorations were returned to their bowers.

Green glass and red wire

Subsequent analysis showed that rural birds often used green glass and green leaves or seeds for decoration, while urban birds preferred green glass and red wire. Plastic items were also popular, although “we also found things like chains, medicine bottles on the bowers near the hospital, and fluorescent mouth guards from a place near the Australian Rules football ground,” Co-author at the University of Exeter Caitlin Evans.

Urban decorations were 10 times more likely to be man-made than those in rural areas, which contained more natural materials, such as fruits, seeds, vegetables, and sticks. Urban habitats also had about five times as many decorations as rural ones, with about 90 items per plot compared to 20 for rural birds. An extravagant city boy collected 300 items to decorate his boat. Both urban and rural male birds show a strong preference for human objects when given a choice of objects from any location. And the red ornaments in the holes in the town were clearer, and the green things were greener, than in the countryside.