Repeated targeting of the same hosts by a brood parasite compromises host egg rejection.
Cuckoo eggs famously mimic those of their foster parents to evade rejection from discriminating hosts. Here we test whether parasites benefit by repeatedly parasitizing the same host nest. This should make accurate rejection decisions harder, regardless of the mechanism that hosts use to identify foreign eggs. Here we find strong support for this prediction in the African tawny-flanked prinia (Prinia subflava), the most common host of the cuckoo finch (Anomalospiza imberbis). We show experimentally that hosts reject eggs that differ from an internal template, but crucially, as the proportion of foreign eggs increases, hosts are less likely to reject them and require greater differences in appearance to do so. Repeated parasitism by the same cuckoo finch female is common in host nests and likely to be an adaptation to increase the probability of host acceptance. Thus, repeated parasitism interacts with egg mimicry to exploit cognitive and sensory limitations in host defences.
1] Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK [2].
Martin
M
Stevens
Jolyon
J
Troscianko
Claire N
CN
Spottiswoode
D000220:Adaptation, Biological; D000818:Animals; D005075:Biological Evolution; D004192:Discrimination, Psychological / Q000502:physiology; D005260:Female; D046369:Finches / Q000502:physiology; D009425:Nesting Behavior; D046109:Passeriformes / Q000502:physiology*; D010364:Pattern Recognition, Visual / Q000502:physiology; D015053:Zygote