Eastern kingbirds are monogamous, although they seem to have a skewed sex ratio, with fewer females than males. Male mates that are lost are quickly replaced by other males. There is some evidence of occasional extra pair copulations or quasiparasitism, where a second female mates with the resident male and lays eggs in the first female's nest. Males perform aerial displays to attract females, they fly in short, zig-zag patterns with their wings fluttering while vocalizing.
Mating System: monogamous
Eastern kingbirds breed from April to June, mostly in May. Females build nests of twigs, bark, and roots lined with softer material, like cattail down or willow catkins. Nests are constructed 2 to 8 m high in trees in open habitats. Females can lay 2nd or 3rd clutches if previous clutches are lost, but if a clutch is successful, there are no additional broods. Females lay 2 to 5, usually 3 cream colored eggs with reddish spots. Eggs are usually laid one per day until the clutch is complete. Incubation is for 14 to 17 days and young fledge 16 to 17 days after hatching. They can reproduce in their first year after hatching, although breeding may be delayed.
Breeding interval: Eastern kingbirds breed once each year.
Breeding season: Eastern kingbirds breed from April to June.
Range eggs per season: 2 to 5.
Average eggs per season: 3.
Range time to hatching: 14 to 17 days.
Range fledging age: 16 to 17 days.
Average time to independence: 30 days.
Range age at sexual or reproductive maturity (female): 1 (low) years.
Range age at sexual or reproductive maturity (male): 1 (low) years.
Key Reproductive Features: seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate)
Young are naked at hatching. Only females incubate and brood the young. Males and females feed nestlings, but females feed more than males. Young are fed insects as much as possible, but parents will provide fruit as well. They remove stingers from bees and wasps before feeding them to the young. Parents continue to feed and protect their young up to 5 weeks after fledging, at 7 to 8 weeks old. Young begin to feed themselves at about 4 weeks old.
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)