Summary:
- Birds reproduce sexually and have separate sexes and internal fertilization.
- Males and females must mate for fertilization to occur.
- Mating is generally preceded by courtship.
- In most species, parents also take care of their eggs and hatchlings.
- Birds are the only nonhuman vertebrates with this level of male parental involvement.
- In polygamous species, where there is more than one mate, one parent does all of the incubating.
- Many seabirds care for their young for extended periods of time.
- Great Frigatebird chicks receive intensive parental care for six months or until they fly.