Figure 3. Male and female plumage colours of Australian landbirds.

In (A) all males (blue and female (red) colours are represented within the tetrahedral colour space of birds. The semi-transparent ‘shrouds’ represents the convex-hull volume occupied by males and females. Rasterized versions in two dimensions, which correspond to the side and bottom ‘shadows’ in (A), are presented in (B) (side shadow) and (C) (bottom shadow) respectively. Colour shading represents whether colours are more abundant in male or female colour samples and lines represent the edges of the tetrahedron in two dimensions.