The coastal city of Pacific Grove in Monterey County, California is known as "Butterfly Town, USA" for the annual migration of the Monarch butterflies. The town's Monarch Butterfly Grove Sanctuary is one of the oldest Monarch over-wintering sights in California, but in recent years their numbers have been dwindling rapidly.
In 2009, the city heavily pruned branches in the sanctuary, and gaps in the tree canopy resulted in Monarch numbers dropping from nearly 18,000 to under 800. The film, "Butterfly Town, USA," centers on a community of activists, led by Bob Pacelli, who took action to save the Monarch Butterfly Grove Sanctuary.
Pacelli and a group of volunteers planted 40 boxed trees to buffer the impact of the trimming. As a result, Monarch numbers increased by more than 500%.
Motivated by their progress, more trees were planted, however this led to a clash between activists and the city about how best to protect the over-wintering site.
Resources
Visit the Monarch Butterfly Resources page for articles on monarch butterflies and their migration, as well as numerous links to monarch conservation organizations and citizen science projects.
