William Rowan was an early 20th century immigrant to Canada who became on of his era’s most famous scientists through research on the Dark-eyed Junco. Before Rowan, it was unknown what environmental cues animals used to time the seasonal changes in their biology. How do animals know when it is time to migrate? or time to breed each year? Through a groundbreaking experiment with the junco, Rowan discovered ‘photoperiodism’ for the first time in animals—but his success didn’t come easily! Shot as an historical re-enactment, this segment provides a glimpse into the history and human dimensions of scientific research, conveys the scientific method, and reveals one of the first studies that made juncos well-known to biologists.