Retaliatory mafia behavior by a parasitic cowbirdfavors host acceptance of parasitic eggs

Why do many hosts accept costly avian brood parasitism evenwhen parasitic eggs and nestlings differ dramatically in appearancefrom their own? Scientists argue that evolutionary lag orequilibrium can explain this evolutionary enigma. Few, however,consider the potential of parasitic birds to enforce acceptance bydestroying eggs or nestlings of hosts that eject parasitic eggs andthereby reject parasitism. This retaliatory