Forster's terns breed in colonies, and are monogamous. Pair formation appears to occur around the time arrival on the breeding grounds in April. Courtship includes a number of displays and postures, including courtship feeding.
Mating System: monogamous
Forster's terns breed in April and May. The female lays 1 to 6 (usually 2 or 3) buff, spotted eggs on a nest dead vegetation. The nest is built on marshy shoreline, on top of a muskrat lodge, or on a mat of floating vegetation. The male and female both participate in incubation, which lasts 20 to 28 days. The chicks are semi-precocial when they hatch; they have open eyes, down, and are able to walk but remain in the nest and are fed by adults. The chicks are brooded by both adults for the first 3 days or so, and are fed for at least 4 weeks. They are able to fly 4 to 5 weeks after hatching. The age of first breeding is unknown, but is believed to be at least 2 years.
Forster's terns breed in April and May. The female lays 2 or 3 eggs that are buff-colored and spotted. The nest is made of dead plant material, and is built on the shoreline, or on top of a muskrat lodge or a floating mat of plants. The parents take turns incubating the eggs for 20 to 28 days. When the chicks hatch, they can walk, but they still depend on the parents to feed them. The parents brood the chicks for about 3 days, and feed the chicks for at least 4 weeks. The chicks can fly when they are 4 to 5 weeks old. They probably do not begin breeding until they are at least 2 years old.
Breeding interval: Forster's terns breed once per year.
Breeding season: April and May
Range eggs per season: 1 to 6.
Average eggs per season: 3.
Range time to hatching: 20 to 28 days.
Range age at sexual or reproductive maturity (female): 2 (low) years.
Range age at sexual or reproductive maturity (male): 2 (low) years.
Key Reproductive Features: seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate)
Average eggs per season: 3.
Brooding behavior is poorly documented in Forster's terns, but adults appear to brood young less than 3 days old and during stormy periods. Both adults feed young at least until they are able to fly, and most likely longer.
Parental Investment: no parental involvement; precocial ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Protecting: Male, Female); pre-weaning/fledging (Provisioning: Male, Female); pre-independence (Provisioning: Male, Female)