Males establish and defend breeding territories in late April to late May. Once a female is accepted into a male's territory, she begins building a nest. The open-cup nest is 10 to 15 cm in diameter and consists of a variety of vegetable material including grass, leaves, mosses, and lichens. Nest location is variable. In the eastern United States nests found on the ground beneath live woody and non-woody plants and in open areas, and in the western United States nests were commonly located above the ground. Females lay 3 to 6 eggs beginning in Late May, and may lay 2nd or 3rd brood as late as August. Egg color ranges from very pale blue to blue-green with few brown flecks. Females begin incubating after final egg is laid, and this period lasts around 12 days. The male feeds the female during incubation.
A hatching bird "pips" the egg, breaks its shell into 2 parts near the egg's greatest diameter. The female removes eggshells from the nest after young hatch. Young are altricial at hatching and have minimal dark grayish down on crown and dorsal feather tracts. The female feeds nestlings with food brought to the nest by the male. Nestling eyes are open by the 3rd day after hatching; full juvenile plumage develops by 10 to 12 days after hatching. Nestlings fledge 10 to 15 days after hatching by leaping from the nest towards a parent on the ground. No information on development from fledging through immature stages is available.
Brood parasitism by the brown-headed cowbird is common, but little is known on how this affects populations of the Hermit Thrush. Recruitment may be limited by nest predation, but little information is available. Studies estimating the probability of fledging at least 1 nestling varied from 17% in Arizona to 37% East of the Rocky Mountains. There is no evidence of cooperative breeding in hermit thrushes.
Breeding interval: These birds once per year, in the spring and summer.
Breeding season: May through August
Range eggs per season: 3 to 6.
Average time to hatching: 12 days.
Range fledging age: 10 to 15 days.
Key Reproductive Features: seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); fertilization (External )
Average time to hatching: 12 days.
Average eggs per season: 3.
Females incubate and deliver food to the nestlings. Males bring food to the nest.
Parental Investment: altricial ; pre-fertilization (Provisioning); 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)