Each year, North American monarch butterflies undergo a spectacular two-way long-distance migration from breeding locations in Canada and the United States to overwintering sites in Mexico. A substantial western population overwinters along the coast of California. Throughout their annual cycle of breeding, migrating, and overwintering, monarchs require different resources at different life stages. Their shifting spatial distribution poses challenges for identifying the key factors that affect monarch population dynamics and, thus, assessing their conservation status. Multiple long-term monarch monitoring programs span timescales of up to 30 years, and collect data on all stages of the monarch life cycle, including egg, larva, and adult density; migration patterns; and disease prevalence. This wealth of data provides an opportunity to understand how natural and anthropogenic factors affect the population dynamics and movement patterns of monarchs in particular, and migratory species in general. To maximize the value of existing data, it will be important to integrate data sets for analysis and interpretation of both within-season and longer-term population trends. This working group will:
1. explore data sets from throughout the monarchs’ annual life cycle to identify the major biological and environmental mechanisms that shape large-scale patterns of abundance and movement
2. predict the consequences of human activities, including shifting agricultural practices, deforestation and climate change, on long-term monarch population dynamics
3. create a web-based portal that allows public access to and use of monarch butterfly observational data, much of which has been collected by volunteer observers
Although our efforts focus primarily on a single species, our questions, approaches and findings will have great relevance in understanding the dynamics of other pollinator species and neotropical migrants across North America.
More information  about this research project and participants.