Lesser yellowlegs are seasonally monogamous, pairs typically don't mate again in subsequent years. Males perform flight displays, accompanied by song, over nesting and foraging areas in the breeding range to attract mates. Males may also behave aggressively towards other males when establishing nesting territories and during courtship. Males guard females from other males during courtship and egg-laying. Extra-pair copulations have not been reported.
Mating System: monogamous
Lesser yellowlegs migrate to breeding areas where they form pairs soon after arrival and begin breeding, usually by mid-May. They form simple nest scrapes and lay 4 eggs (maximum 6) in June and July. They may dig and line up to 75 nest scrapes before deciding on a final one. Scrapes are placed in elevated, mossy, dry areas, with overhanging vegetation and within 200 meters of water. Eggs are generally buffy, gray, brown, or green with brown spots. Although lesser yellowlegs may re-nest after a nest failure, it is likely that pairs raise only 1 brood yearly. Eggs are incubated for 22 to 23 days and eggs hatch within a few days of each other. Young leave the nest within a few hours of all eggs hatching and can fly within 22 to 23 days after hatching. They are independent from 23 to 31 days after hatching. Some lesser yellowlegs attempt to breed in their first year of hatching, but more attempt their first breeding at 2 years old.
Breeding interval: Lesser yellowlegs breed once yearly in general, although individuals may skip breeding years.
Breeding season: Lesser yellowlegs breed in May each year.
Range eggs per season: 6 (high) .
Average eggs per season: 4.
Range time to hatching: 22 to 23 days.
Range fledging age: 22 to 23 days.
Range time to independence: 1 to 9 days.
Range age at sexual or reproductive maturity (female): 1 (low) years.
Average age at sexual or reproductive maturity (female): 2 years.
Range age at sexual or reproductive maturity (male): 1 (low) years.
Average age at sexual or reproductive maturity (male): 2 years.
Key Reproductive Features: seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate)
Both parents incubate and brood the young. Young are precocial at hatching and can get around on their own and feed themselves within hours. Parents lead young to foraging areas by flying ahead, landing, and then calling to the young. Both parents continue to protect the young until they fledge or a few days longer, although females may abandon males with the young. Females generally stay with the young for about 11 days after hatching, males stay with them for about 26 days after hatching.
Parental Investment: precocial ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Male, Female); pre-weaning/fledging (Protecting: Male, Female)