specialization 6 Antiparasitic defences 4 Aves 4 Brood parasitism 4 Host specialization 4 Mimus saturninus 4 Molothrus 4 Molothrus rufoaxillaris 4 Screaming cowbird 4 Troglodytes 4 Troglodytes aedon 4 agelaioides badius 4 antiparasite defense 4 article 4 bird 4 brood parasite 4 brood parasitism 4 coevolution 4 controlled study 4 ecological specialization 4 egg 4 experimental study 4 hatching 4 host parasite interaction 4 host preference 4 host range 4 host resistance 4 host selection 4 host-parasite interaction 4 hypothesis testing 4