Cowbird Brood parasitism 10 Molothrus 8 Aves 6 Egg rejection 6 Molothrus bonariensis 6 bird 6 brood parasitism 6 passerine 6 Molothrus ater 4 adaptation 4 animal behavior 4 article 4 egg 4 egg rejection 4 nonhuman 4 parasitism 4 3D printing 2 American robin 2 Animalia 2 Animals 2 Article 2 Artificial egg 2 Begging 2 Behavior, Animal 2 Birds 2 Brown-and-yellow Marshbird 2 Chick rejection 2 Coevolution 2 Coturnix 2