Final answer:
The mating system most prevalent in birds is monogamy.
Step-by-step explanation:
In monogamous systems, one male and one female are paired for at least one breeding season. This behavior is advantageous in situations where mates are scarce and difficult to find. Monogamy is observed in many bird populations where, in addition to the parental care from the female, the male is also a major provider of parental care for the chicks.