A red squirrel mother carries her 25-day-old pup to a new nest. The Kluane Red Squirrel Project, located in the southwest Yukon, is a long-term research initiative that studies the ecology and evolution of North American red squirrels (Tamiasciurus hudsonicus). One of the unique aspects of red squirrels, which makes them a good study system, is the fact that we can easily follow individuals through their entire lives, from birth until death. In this photo our team of researchers has just given this pup (baby squirrel) a set of unique ear tags which will allow us to identify this individual when it leaves its mother's nest and establishes its own territory. In this way we can learn about the factors that affect a red squirrel's ability to survive and reproduce in the harsh northern landscape of the Yukon.