Bird Monogamy Mating
More than 90 percent of the world's bird species are monogamous. In monogamous species, the male and female remain together for the purpose of raising a brood of young. The male and female pair early in the breeding season and share parental duties. The responsibility for territorial defense usually falls upon the male, which is one reason why males sing so much in spring; it is their principals contribution to the nesting effort.
The female's main task is to produce the eggs. The female invests enormous energy in this task, supplying each egg with nutrients that will sustain the chick before hatching. Although the male cannot produce eggs itself, it often provides the female with food to make the job a little earlier. In many species "couples" last for more than one year, though they may not be lifelong pair-bonds. Even swans, renowned for their long-term pairing, go through a "divorce" on occasion. Studies show that roughly 5 percent of breeding pairs of Mute Swans separate each year. In many species pairs are more likely to remain together the next year if they have been successful in raising young during the current year.
Left: The Dunlin forms a monogamous pair-bond with its mate. Throughout the breeding season, care for the eggs and young is divided equally between the two birds.