"Fool me once, shame on you. Fool me twice, shame on me." This common adage applies to a new study in which scientists used 3D-printed eggs to show how wild birds reject nest imposters.
Bird nests, though it may not seem like it, are incredibly diverse, differing in nest location, structure, materials, and more. For instance, they could be on the ground or hanging from a tree, made out of twigs and grass, or even saliva. Yet despite their variety, we know very little about the forces that shaped their evolution. Now, new research is shedding light on the subject.