Fig. 2
From: Egg rejection and egg recognition mechanisms in Oriental Reed Warblers
Egg recognition experiments in nests of the Oriental Reed Warbler. a refers to experimental nest with adding one blue model egg; b and c refer to experimental nests with two experimental eggs and two host eggs (i.e., 2 + 2), while experimental eggs in b are white model eggs and c are white budgerigar eggs; d refers to experimental nests with one host egg and three budgerigar eggs (i.e., 1 + 3)