Behaviour related to the production of offspring; it includes such patterns as the establishment of mating systems, courtship, sexual behavior, parturition, and the care of young. Successful reproductive efforts require the establishment of a situation favourable for reproduction, often require behaviour leading to the union of male and female gametes, and often require behaviour that facilitates or ensures the survival and development of the young; the mere union of gametes is not generally sufficient for successful reproduction.

For each species, there is a complex set of behavioural adaptations that coordinate the timing and patterning of reproductive activity. Typically, this entails integration of both overt behavioural and internal physiological events in both male and female, all of which are intricately enmeshed in manners adapted to the environment in which the animals live. The behavioural patterns related to reproduction tend to be relatively stereotyped within a species, but diverse among different species—especially distantly related species. The end products of cycles of reproductive activity are viable, fertile offspring which, in turn, will reproduce and thus perpetuate the species.