Imagine that the city of Los Angeles had shrunk to the size of the town of Monterey. You’d be shocked. Basically, that is what has happened to the monarch butterflies that overwinter in California. At Thanksgiving 2018, the population of western monarchs hit a record low of less than 29,000 butterflies, a decline of 99.4% since the 1980s, when the number of monarchs flying to California for the winter is estimated to have been 4.5 million. For every 160 monarchs there were 30 years ago, there is only one left flying today.
The significant problems afflicting western monarchs are habitat loss (overwintering and breeding areas), pesticide use (herbicides and insecticides), and climate change (including increased drought severity and frequency). Research into monarch losses is active and ongoing, but the depth and abruptness of the recent declines means that we need to act now based on the available evidence. The western monarch population may collapse completely if we wait until all of the answers are fully in focus.
Western monarchs are in trouble, but there are concrete actions that we can all take to help them recover. The Xerces Society is taking action for monarchs in California. Working with farmers, natural area managers, California cities, and others we are planting and restoring habitat across the Central Valley—a key breeding and migration area for monarchs. In the last 18 months, we have restored 20 miles of hedgerows on farms, and in the coming year, we will be adding another 10 miles to further re-connect habitats. These hedgerows provide essential nectar sources, milkweed for breeding, and unsprayed refuge. Xerces is also pushing for protection for overwintering sites and working with partners to restore overwintering habitat.
Will you help us in this task?
The actions listed in this document are based on our current understanding of stressors that impact the monarch specifically, as well as butterflies more generally, and also on the precautionary principle in which we take measures to reduce risks to the monarch population while we are working to better understand these risks. Thank you for your support!