Buteo lagopus will usually migrate solo (very uncommon to fly in groups) and find a mate once they have reached their destination. Males will soar and circle until a female joins them. Rough-legged hawks perform courtship displays in the late winter, once it has began to get warmer and flying conditions improve. After a male is joined by a female, both sexes soar together with their tails and wings fully spread. Males then perform a "Sky-Dance" dislay, in which they soar high, suddenly dive, climb again, free fall, and finally, climb back up to a normal soaring height. Male rough-legged hawks defend their mates from other males by taking flight and chasing rival males.
Male and female rough-legged hawks build a nest together after they have found a suitable site on a rocky cliff. Males carry most of the building supplies while females construct the nest of twigs, grass, molted feathers, and fur from prey. Even objects such as caribou bones are sometimes incorporated into nests. Nests take three to four weeks to build and are usually 60 to 90 cm in diameter and 25 to 60 cm deep.
Mating System: monogamous
Rough-legged hawks breed once a year, usually between April and June, but breeding has also been reported in July. There are 2 to 7 eggs per clutch and they take a minimum of 31 days to hatch. Fledging usually takes more than 40 days, although some fly weakly at 31 days old. The young are not fully independent of the parents until 2 to 4 weeks after they leave the nest, at 55 to 70 days old. The period of independence sometimes extends into migration. Sexual maturity of males and females is reached at 2 to 3 years.
Breeding interval: Breeding occurs once a year.
Breeding season: Breeding typicalls occurs from April to June, occasionally July.
Range eggs per season: 2 to 7.
Average eggs per season: 4.
Range time to hatching: 31 (low) days.
Range fledging age: 31 (low) days.
Average fledging age: 40 days.
Range time to independence: 55 to 70 days.
Range age at sexual or reproductive maturity (female): 2 to 3 years.
Range age at sexual or reproductive maturity (male): 2 to 3 years.
Key Reproductive Features: seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); fertilization
Both male and female Buteo lagopus provide for and protect their young from the time the eggs are laid until the young hawks are independent (55 to 70 days post-hatching). After the eggs are laid, the female will incubate them, while the male will hunt for food for both parents. The male will continue to hunt for both adults until the young hatch. Once the young have hatched, the female will begin to hunt to ensure that there will be enough food for both the young and the adults. Both parents will also guard the nest and ward off other birds and predators.
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)
