Final answer:
Male birds of similar age are important for successful parental care and increasing the chances of offspring survival.
Step-by-step explanation:
The male birds being of similar age is important because it increases the chances of successful parental care. When male birds are of similar age, they are more likely to have similar energy levels and physical capabilities, which are important for providing care to the offspring. For example, in species where males assist with parental care, such as courtship rituals or providing food, having similar age males ensures that the offspring will receive consistent care and have a higher chance of survival.