There's been a mockingbird singing loudly lately near my office. S/he likes to perch on top of a tall conifer between the Carriage House (where my office is) and the Geology Museum, and hold forth for some time.
Mockingbirds are unusual because they sing practically all year-round, not just in breeding season, and their song cycles mimic so many other bird songs as well as other sounds that they've heard.
Sometimes I'm easily able to pick out the songs that are mimicked (in the sound clip in this link, listen for Carolina Wren, Tufted Titmouse, and Eastern Towhee!)
In fall, both males and females sing, staking claim to feeding territories rich with berries and other fruits.