Horned grebes begin breeding when they are 1 year old, and usually raise one brood per year. Breeding pairs form in the winter or spring, and may breed together for more than one year. Like other grebes, horned grebes have complex courtship rituals. Both the male and female may perform these displays, and many displays are performed together. For example, the male and female run on top of the water together with their “horn” feathers raised, then dive together, and then run along the water together again with pieces of plant in their bills. These ceremonies are one way that members of a pair communicate with each other.
Mating System: monogamous
Horned grebes begin breeding when they are 1 year old, and usually raise one brood per year. They breed between mid-May and early October. The male and female both build the nest, which is located in shallow water among vegetation. The nest is made of floating wet plant material, and is attached to standing vegetation.
The female lays 3 to 8 (usually 5 to 7) eggs at a rate of approximately one every other day. The eggs are whitish to buff when they are laid, but they quickly become stained red and brown from the nest material. Both parents incubate the eggs for 23 to 24 days. The precocial chicks are able to swim and dive immediately after hatching, but are often seen riding on their parent's back for the first week after they hatch. The parents brood the chicks for about 9 days after hatching, and feed them for up to 14 days. Chicks become independent at 20 to 25 days old, but cannot fly until they are 41 to 50 days old.
Breeding interval: Horned grebes breed once yearly.
Breeding season: Horned grebes breed between mid-May and early October, with peak activity occurring June through August.
Range eggs per season: 3 to 8.
Average eggs per season: 6.
Range time to hatching: 23 to 24 days.
Average fledging age: 0 days.
Range time to independence: 20 to 25 days.
Range age at sexual or reproductive maturity (female): 1 (low) years.
Average age at sexual or reproductive maturity (female): 1 years.
Range age at sexual or reproductive maturity (male): 1 (low) years.
Average age at sexual or reproductive maturity (male): 1 years.
Key Reproductive Features: seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate)
Average eggs per season: 4.
Both adults build the nest and incubate the eggs. After the chicks have hatched, horned grebe parents carry them on their backs often for the first 10 days. They also feed the chicks for 10 to 14 days after hatching.
Parental Investment: precocial ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Protecting: Male, Female); pre-weaning/fledging (Provisioning: Male, Female, Protecting: Male, Female); pre-independence (Provisioning: Male, Female, Protecting: Male, Female)