Female cuckoo calls elicit anti-predatory behavior in birds

Imperfect Batesian mimicry is common in nature. Female common cuckoos ( Cuculus canorus ), for instance, seem to be imperfect mimics of hawks ( Accipiter spp.) in both appearance and call. However, only few experiments have confirmed that female cuckoos can effectively mimic sparrowhawk calls. To test the effectiveness of female common cuckoos mimicking the call of hawks, we performed a playback experiment on two host bird species, namely the Oriental magpie-robin ( Copsychus saularis ) and white wagtail ( Motacilla alba ), and two potential host bird species, the crested myna ( Acridotheres cristatellus ) and Eurasian hoopoe ( Upupa epops ), during the non-breeding season in Hainan island, China. We found that while there are significant differences in the likelihood that different species respond to playback call types, they do not differ in how they respond to the different calls, and that overall, the birds are more likely to respond to female cuckoo and hawk calls than to dove or male cuckoo calls, and with no significant difference between hawk and female cuckoo. Our results show that although female common cuckoos mimic the call of sparrowhawks imperfectly, they can mislead birds into displaying anti-predatory behavior. This study provides further evidence to support the recently proposed hypothesis that hawk mimicry in female cuckoo calls can not only fool their hosts, but also the non-host species.