North Queensland Naturalist 51: 98-102


Male Great Bowerbirds (Ptilonorhynchus [Chlamydera] nuchalis) build and decorate stick structures (bowers) to attract females. In some populations, they arrange grey and white decorations by size, with smaller decorations closer to the bower entrance. This size-distance gradient has been hypothesized to create a “forced perspective” illusion that females prefer. I assessed whether a common type of red decoration – red wire – was also arranged by size at 18 bowers in Townsville, Queensland. Males placed shorter wires closer to the bower structure, but most wires were outside of the females’ field of view, precluding them perceiving forced perspective. Instead, males might keep shorter wires closer to the bower because they frequently use red wires during display, and shorter wires might be easier to handle during display movements. Longer wires farther away might aid in long-distance mate attraction.