15. Singing for more and more mates.
3. Why and How Birds Sing
Why sing?
From page 30 in the book.
Singing for more and more mates. Spend some time quantifying the efforts of an overtly polygynous songbird and you soon realize that a lot of his day is spent singing and addressing females. A dickcissel seems to sing all day long. A marsh wren sings and builds multiple nests for prospective mates throughout the day, and sometimes sings through the night. The singing season of polygynous birds can also extend much later into the breeding season than it does for typically monogamous species, such as a brown thrasher or black-throated blue warbler, in which one male and one female pair.