Figure 3.

Extinction and replacement of Cygnus swans following human colonization of NZ and CI. At the time of human arrival in the NZ region (a) C. atratus was restricted to Australia, while C. sumnerensis was restricted to NZ. Within 200 years of human settlement (b), C. sumnerensis was extinct. During the late nineteenth century (c) C. atratus was deliberately introduced to NZ, though there is evidence for self-introduction around this time (and possibly prior to this). Red, modern (Australia) C. atratus; blue, prehistoric (NZ) C. s. sumnerensis; light blue, prehistoric (CI) C. s. chathamicus. (Online version in colour.)