... simultaneously integrate these features together when recognizing eggs remains an open question. Here, we tested egg rejection responses of American robins ( Turdus migratorius ) using a range of 3D-printed model eggs covered with blue and yellow checkered patterns differing in relative square sizes. We...

... cowbird ( Molothrus ater ). We hypothesized that the degree of contrast between foreign eggs and the nest background would affect host egg rejection behavior. We predicted that experimentally decreasing egg–nest chromatic and achromatic contrast (i.e. rendering parasitic eggs more cryptic against the nest...