Repeated targeting of the same hosts by a brood parasite compromises host egg rejection.

Abstract in brief

• Repeated parasitism by the same cuckoo finch makes it harder for host birds to reject foreign eggs, as hosts become less likely to do so when exposed to multiple foreign eggs.
• Hosts typically reject eggs that differ from their internal mental template, but as more foreign eggs are introduced, hosts require them to look more different to reject them.
• This strategy of repeated parasitism likely helps cuckoo finches improve their chances of success by exploiting the hosts' cognitive and sensory limitations in recognizing and rejecting foreign eggs.]