Figure 2.

(a) Sonograms of reed warbler-cuckoos from the cross-fostering experiment, comparing those raised by their intended host, reed warblers (n=9: five individuals shown), with those raised by either robins (n=3) or dunnocks (n=5). (b) Discriminant function analysis separating these 17 reed warbler-cuckoos by their raising host species: (i) reed warblers (black diamonds), (ii) robins (black circles) or (iii) dunnocks (black triangles). For each raising host species, the sonograms are arranged in the same order (left to right) as the samples in this graph (the five reed warbler-raised individuals illustrated are numbered). For comparison, we have shown how this discriminant function analysis separates the field recordings of calls of naturally raised reed warbler-cuckoos (RW-C: n=14, open diamonds) and dunnock-cuckoos (D-C: n=9, open triangles). Arrows indicate group centroids.