DNA sequencing is on par with Roger Tory Peterson's first field guide, advances in the quality of optics, and the proliferation of digital technology in changing the way we approach birding. Yet for all the attention that "splits" and "lumps" garner--most of them the result of genetic studies--we still don't have a perfect explanation for the fundamental question "What is a species?" Josh Engel, who studies bird genetics at the Field Museum, will explain how DNA sequencing works and why it has led to such dramatic rearrangements of our field guides. He will discuss some of the most surprising results of DNA studies, along with how we know that Yellow-breasted Chat is not a warbler and why there could soon be three species of White-breasted Nuthatches.