The Pew Charitable Trusts
March 28, 2022
Each spring, millions of monarch butterflies leave their overwintering sites in the Sierra Madre mountains of central Mexico and begin their annual migration north across the United States.
The exodus and return of the iconic orange and black butterfly is one of the grandest spectacles of the natural world. But that sight is becoming increasingly rare as the monarch’s population has shrunk by nearly 90% in the past two decades, according to federal scientists.
The monarch faces many threats, including the loss of milkweed and other flowering plants across its range, degradation and loss of overwintering groves in both coastal California and Mexico, and the widespread use of herbicides and pesticides. Many of these stressors are worsened by climate change, according to advocates.
In the past two years, some state transportation departments, local governments and energy companies across 23 states have committed to preserving monarch habitat in hopes of protecting the species and preventing it from being added to the federal endangered species list.