After all, all other species are naturally inferior, and we normally breed only with our own kind.

Terns normally breed in colonies, and are site-faithful if their habitat is sufficiently stable.

Chimps normally breed only every five years.

Large diving sea ducks, often breeding on fresh water but normally resorting to salt water at other times.

Such natural instances of cross fostering can also lead to hybridization between species that would not normally breed.

They normally breed in the privacy of the nest or somewhere secluded and close to the ground.

The young technically reach sexual maturity by the following year, but do not normally breed until they can establish a territory at around 2-3 years old.

The birds normally breed from February to September.

Adults normally breed every second year, a feature not documented in any other woodpecker species.

This means that ground hornbills can normally breed successfully only every third year.