Swallow-tailed kites are monogamous, although pair bonds are not necessarily maintained between breeding seasons. Females and males will approach each other on a horizontal tree limb. The female will quickly go under the limb or turn, bending forward with the wings extended. The male lands on her back and drapes his wings over the female, then mating occurs. There is also courtship feeding.

Mating System: monogamous

Swallow-tailed kites breed once per year, usually in April. They produce loud shrills, squealing calls, and whistles during the mating season.  Females usually lay two eggs per clutch. The eggs are incubated for approximately 28 days, and the fledgling period lasts anywhere from 36 to 42 days. Fledglings can take an additional 2 weeks or more to become independent.

Breeding interval: Swallow-tailed kites breed once yearly.

Breeding season: The breeding season is short and usually occurs in the month of April.

Range eggs per season: 3 (high) .

Average eggs per season: 2.

Average time to hatching: 28 days.

Range fledging age: 36 to 42 days.

Range time to independence: 50 (low) days.

Key Reproductive Features: seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate)

Not much is known about the degree of parental investment in swallow-tailed kites. Both parents incubate the eggs. When one parent comes in to sit on the eggs, the other flies straight up from the nest. The incoming parent hovers over the nest, and then gently settles down. Young are altricial. In their close relatives males bring back food while females watch the young and protect the nest. Towards the end of the nesting period both parents will hunt. After fledging the adults continue to provide food for their young.

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)