Journey North, a program of the University of Wisconsin–Madison Arboretum, is one of the largest and longest standing citizen science programs in North America. Founded in 1995, Journey North's mission is to engage an audience across North America in tracking migration and seasonal change to foster scientific understanding, environmental awareness and the land ethic.All across North America, citizen scientists report their observations of migratory species to the Journey North website. Through Journey North, participants can watch migration unfold in real time, predict when species will arrive, and look for trends and changes in migration patterns. Migratory species are particularly important indicators of impacts of environmental changes. These species depend on a suite of conditions in different habitats in order to complete their annual migratory cycles. This dependence might make them more vulnerable to change. On the other hand, migratory species have evolved to move from one location to another to find the conditions they need to survive, and thus might be better able to adapt to changing conditions. Data from Journey North will help us determine how species respond to year-to-year variation in weather conditions, as well as changes in habitat availability.