For instance the male long-billed marsh wren (Cistothorus palustris) is polygamous in Washington, where swamps vary in quality and females are attracted to those few males who have rich territories, leaving the less lucky ones to a life of enforced bachelorhood. The same wrens are monogamous in Georgia, not so much because that state is part of the Bible Belt, but because the marshes all have roughly the same amount of food and cover, and so each male can attract a doting spouse to an equally comfortable nesting site.
