Males and females form a pair bond during breeding season and while raising their young.
Mating System: monogamous
American robins breed in the spring shortly after returning from their winter range. The breeding season extends from April through July. American robins are one of the first birds to begin laying eggs each spring. They normally have two or three sets of young (broods) in each breeding season. 3 to 5 eggs are laid in each clutch. ("Clutch" means the group of eggs laid in one nest attempt. "Brood" means the number of baby birds that hatch out of the eggs, so the brood may be smaller than the clutch.)
A new nest is built for each clutch of eggs. The female robin builds the cup-shaped nest. The outer foundation is made from long coarse grass, twigs, paper, and feathers woven together. She smears mud onto the inner bowl with her breast. She later lines the inner bowl with fine grass or other soft material. This lining helps cushion the eggs.
The nest can be located on the ground or high up in trees. They are most commonly found 5 to 15 feet above ground. Robin's nests might be in a dense bush, in the crotch of trees, or on window ledges or other human structures. All of these provide a firm support and protection from rain. In northern areas the first clutch is generally placed in an evergreen tree or shrub. The later clutches are laid in a deciduous tree.
Breeding interval: American robins breed once or twice yearly.
Breeding season: American robins breed from April to July.
Range eggs per season: 3 to 5.
Average time to hatching: 14 days.
Average fledging age: 13 days.
Average age at sexual or reproductive maturity (female): 1 years.
Average age at sexual or reproductive maturity (male): 1 years.
Key Reproductive Features: seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate)
Average time to hatching: 13 days.
Average eggs per season: 4.
Eggs are incubated by the female, which means that she sits on the nest to keep the eggs warm until they hatch. After about 14 days of incubation the eggs hatch. She continues to feed and brood (keep them warm by sitting on them) the chicks while they are very young. When the nestlings become older the female broods them only at night or during bad weather. Baby birds leave the nest about 2 weeks after they have hatched. All babies from a clutch leave the nest within 1 day of each other. Even after leaving the nest, the young birds follow their parents and beg food from them. They remain under cover on the ground during this time. Fledging is when baby birds leave the nest. About two weeks after fledging, young American robins become capable of sustained flight.
Parental Investment: altricial ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Male, Female, Protecting: Male, Female); pre-independence (Provisioning: Male, Female, Protecting: Male, Female)