Male great bowerbirds build elaborate tunnels of twigs and adorn them with random objects to attract mates. In Australia’s northern Queensland, researchers from the University of Exeter tracked 61 males across a rural station and an urban city during the 2023 breeding season. The study revealed stark differences in the materials chosen for courtship displays.

Urban birds collected more than ten times as many human‑made items, averaging 90 per bower versus 20 in rural sites. green glass and red wire dominated city decorations, while rural males favored green leaves and seeds. A single urban male assembled nearly 300 items, showcasing the scale of human influence on avian aesthetics.

Both urban and rural males showed a strong preference for human objects when offered a mix of urban and rural items. The brighter reds in city bowers contrasted with duller greens, suggesting visual cues may shift with material availability. Researchers argue that easier access to synthetic objects could lower the energetic cost of display maintenance.

The findings highlight how urbanization reshapes animal behavior beyond habitat loss. While the study stops short of linking material choice to mating success, it underscores that human debris can become a new currency in wildlife courtship. This research reminds us that ordinary trash can alter evolutionary pressures in unexpected ways.