Figure 1

Three sets of experiments to test for enemy recognition and mimicry hypotheses (see Introduction). Response (aggression measured as number of contact attacks per 1 min.) is presented as a difference (mean ± s.e.) between aggression levels towards two dummies within a simultaneously presented dyad (see Methods). For sample sizes see Table 1. (a) “Specific aggression” is the aggression to cuckoo/predator dummy minus baseline aggression to control (dove), i.e., specific response to the dangerous enemy above the background aggression shown to any, even innocuous, intruders near the nest (see [18]). (b) Difference between responses to paired gray vs. rufous cuckoo female morph. (c) “Mimicry” is the aggression towards a particular cuckoo morph minus aggression towards its respective model (i.e., sparrowhawk for gray morph, kestrel for rufous morph). Different letters indicate statistical differences between groups according to GLMM (Tukey HSD, α = 0.05).