5. Selection on Signals
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Figure 5.7. Sonograms (2.5 sec) of the begging calls of (top) a single reed warbler chick, (middle) a brood of four
reed warblers, and (bottom) a single cuckoo chick. Note the similarity between the begging call of the single cuckoo
and an entire brood of their reed warbler host. (Redrawn from Davies et al. 1998.)