The female builds the cup-like nest with mud as its foundation and lines it with grasses, twigs and other plant material before laying bright blue robin eggs. “I’ve watched American robins ...
Of these, only predation seemed to be affected by snakeskin: eggs in cavity nests containing snakeskin were more likely to survive the two-week test period than were eggs in plainer nests.
Birds that lay their eggs in other birds' nests are called brood parasites. They don't build their own nests These birds leave their eggs in "someone else's" nest and rely on the host birds to ...