When the team returned to the sites, they determined which decorations had been selected from mud piles and moved to a bower, and whether it came from an urban or rural source. After recording the data, all the original decorations were returned to their bowers.
green glass and red wire
A male Great Bowerbird displaying a female Great Bowerbird in a rural setting. Credit: Caitlin Evans
Subsequent analysis revealed that rural bowerbirds often use green glass and green leaves or seeds for decoration, while urban birds prefer green glass and red wire. Plastic objects were also popular, although co-author Caitlin Evans of the University of Exeter said, “We also found objects including a pair of handcuffs, medicine jars in Bowers near the hospital, and a fluorescent mouth guard from a site near an Australian rules football field.”
Urban bower decorations were 10 times more likely to be man-made than rural bowers, which contained more natural items such as fruits, seeds, leaves and sticks. Urban bowers also had about five times more decorations than rural ones, with an average of 90 items per bower compared to an average of 20 for rural birds. An overachieving urban man collected 300 items to decorate his garden. When given a choice of objects from each environment, both urban and rural male bowerbirds showed a strong preference for human objects. And red decorations in urban bowers were brighter, and green objects were duller than in rural bowers.
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