Skip to Content

Eastern monarch population declines 26%

Feb 25, 2021


  • Population Trends

Written by Wendy Caldwell

Executive Director, Monarch Joint Venture


While the past year has had no shortage of hardships, hearing the news that the eastern population declined 26% from last year to 2.10 hectares is devastating. Scientists estimate that at least 6 hectares is necessary for a sustainable population of eastern monarchs.

The news of further decline in the eastern population commands heightened attention for all of North American monarch conservation. As our community gathered itself and began developing a rapid-action response to the western population crisis, the urgency of conserving the eastern population now feels equally pressing.  

I have been a part of and witnessed the growth of this expansive network of organizations working across North America to protect monarch butterflies for nearly 15 years, and it has been amazing. But, where we go from here, together in partnership, is what matters most for saving the monarch migration. We are in this together, and we need each other - no agency, NGO, or sector can do this on their own. It is not just about everyone doing their part and “all hands on deck”. If we lose hope now, the loss of monarchs becomes inevitable. Instead, I urge us to find hope in the movement for pollinators, and to use this news of declining populations as the spur to join or increase our collective actions.  We must find new ways to work together, to leverage and support each other, and to cultivate a network of people and partners for a better tomorrow - for the butterflies and for ourselves.


The original Spanish-language press release from WWF on the 2020-2021 overwintering numbers, released February 25, 2021 is available here. A translated version is available here

The Monarch Joint Venture is a 501c3 nonprofit organization and a national partnership of federal and state agencies, non-governmental organizations, businesses and academic programs working together to conserve the monarch butterfly migration. The content in this statement does not necessarily reflect the positions of all Monarch Joint Venture partners. Header photo taken by Wendy Caldwell in Mexico in 2018.