Among American Robins, the female does most of the nest-building. She starts by selecting a good site. Usually, this is a place protected from rain, wind, and sun, often on tree branches hidden by leaves. Then, using grasses and small twigs, she forms a cup-shaped nest. After forming this cup, the robin adds mud to reinforce it and cement it to its location on the tree branch or other base. Finally, she lines the nest with soft grasses and hairs. All this usually takes about five or six days, and it results in a fine home, about six to eight inches across and three to six inches high.
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