Chipping sparrows have long been considered largely monogamous. However, polygyny and extra pair copulations are documented and incidence may be high in some populations. Recent research suggests that males travel widely outside of their territories in search of additional mating opportunities. Mated pairs form soon after males have arrived on the breeding grounds and established a territory. Males attract females with their songs and chase them or perform displays on the ground. Males and females display to each other by collecting nest materials while together. Females beg for food from males as well. Males guard females after copulation to prevent extra pair copulations. Pairs may stay together through a breeding season or new pairs may be formed throughout the season. There are a few reports of helpers at the nest.
Mating System: monogamous ; polygynandrous (promiscuous) ; cooperative breeder
Chipping sparrows breed from mid to late April through July. Pairs begin building nests within a few weeks of arriving on the breeding grounds. Males and females choose a nest site, usually in a conifer tree or shrub from 1 to 3 meters above ground. They are usually built in thick vegetation to provide cover. Females build nests out of grasses, roots, and other fine materials. If the first clutch fails, a second nest will be built and a second clutch attempted. Most chipping sparrows successfully raise 1 brood, although 2 nesting attempts is typical. Females lay from 2 to 7, usually 4, pale blue eggs with brown blotches at the wider end. They lay 1 egg per day and begin incubating just before the last egg is laid. The incubation period is 7 to 15 days, but usually 10 to 12. Fledging occurs at 8 to 12 days and young become fully independent several weeks after fledging. Males and females can breed in their first year after hatching.
Breeding interval: Chipping sparrows usually attempt 2 broods each breeding season, sometimes 3. However, typically only 1 brood is successful each season.
Breeding season: Chipping sparrows breed from mid to late April through July.
Range eggs per season: 2 to 7.
Average eggs per season: 4.
Range time to hatching: 7 to 15 days.
Range fledging age: 8 to 12 days.
Range time to independence: 3 to 5 weeks.
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)
Males and females defend a breeding territory and protect young against predators. Newly hatched chipping sparrows are naked and helpless, but grow quickly, becoming fully feathered at 6 days after hatching and about 80% of adult weight and able to fly as soon as 8 days after hatching. Females incubate the eggs and brood the young and males feed females on the nest. Males are responsible for most feeding of nestlings for the first few days. Males will often give food items to the female in the nest, who then passes them to the young. If a female attempts a second brood, the male may be left to care for the previous brood. Young are fed seeds and insects and parents carry fecal sacs away from the nest. Once the young have fledged, they remain near the nest with their parents for another few weeks, when they become independent. Juveniles then form flocks with other young birds.
Parental Investment: altricial ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Male, Female); pre-weaning/fledging (Provisioning: Male, Female, Protecting: Male, Female); pre-independence (Provisioning: Male, Female, Protecting: Male, Female)