Development of sexual signals in bowerbirds (Ref: 4235)

Male bowerbirds are famous for their complex courtship displays that incorporate a bower decorated with coloured objects, vocalisations, and vigorous display movements. Male great bowerbirds (Ptilonorhynchus nuchalis) also use their bowers to create visual tricks that affect the viewing female's perception of the decorations that he presents during display. Despite the variety of signals that males produce when courting females, little is known about how the male constructs his bower, how his physical display movements interact with the bower display, and whether males adjust bower appearance or courtship displays in response to social and environmental changes. This project will quantify the female perspective of male displays to address novel questions about construction behaviour, multi-component courtship displays, perception, and female choice.

Project Aims and Methods

This project will increase our understanding of movement-based courtship displays and their interaction with an extended phenotype by addressing the following questions:

1. How do males build bowers? Males build a new bower every year, and bower size and composition appear to vary across individuals. By quantifying how males construct and decorate their bowers, we will investigate variation in building behaviour and explore parallels with nest building behaviour more broadly. We will also use data from bower measurements and male displays to determine whether there are trade-offs or positive associations in the quality of different display components.

2. Are courtship displays indicators of skill? When displaying to females, males pick up, shake and toss a variety of coloured objects, interspersed with presentations of their pink crest. By videoing the male's display from the female's point of view from within the bower and using markerless object tracking software, we will quantify how the motion of both the male and the objects he displays are perceived by the female, how males vary in their displays, and whether females prefer males that produce more skilful or vigorous displays.

3. Do males improve their displays over time? Immature males spend up to seven years learning how to build bowers, and changes in display quality over time are poorly understood in this species. By quantifying the changes in building behaviour and courtship displays of individually identifiable males over multiple years, we will gain insights into the development of courtship behaviour, and will quantify the effects that social and environmental factors have on display quality.