View & Download WMC Data


The Thanksgiving Count & New Year’s Count are products of annual monitoring efforts of overwintering monarchs in the West.

Data are collected from various overwintering sites located along the California coast, Northern Baja, Mexico, and a few inland sites in California and Arizona. Thanks to the extraordinary efforts of 100+ volunteers, we now have 25 years of data demonstrating that overwintering western monarchs have undergone a >95% decline since the 1980s. Data collected by volunteers are compiled and entered into the Xerces Society’s Western Monarch Overwintering Sites Database which also includes many historic counts and survey efforts. Contact [email protected] if you are interested in obtaining a copy of the entire database.

Download data for all years (1997-2022) *NOTE: If you are a researcher using this data, be sure you periodically check back to make sure you have the most recent version. Data were last updated on August 28th, 2022.

Data Citation: Xerces Society Western Monarch Count. 2022. Western Monarch Thanksgiving Count and New Year’s Count Data, 1997-2021. Available at www.westernmonarchcount.org.


Results from the 2021 Western Monarch Thanksgiving Count:

Volunteers counted nearly 250,000 butterflies at overwintering sites in the West, an over 100-fold increase in abundance from 2020’s all-time low of less than 2,000 monarchs. Read our Blog and Press Release for complete summaries of the 25th annual Western Monarch Thanksgiving Count, which occurred November 13 – December 5, 2021.

Figure 1. Total monarchs reported and number of overwintering sites monitored for the Western Monarch Thanksgiving Count from Nov. 1997 to Dec. 2021.


Results from the 2021-2022 Western Monarch New Year’s Count:

Volunteers counted 151,168 butterflies across 209 overwintering sites for the New Year’s Count, revealing an average seasonal decrease of ~38% over the winter season for the 196 sites monitored during both the Thanksgiving and New Year’s Count; this decrease aligns with the trends we usually witness. Read our blog for a complete summary of the 2021-2022 New Year’s Count, which occurred December 25, 2021 – January 9, 2022.

Figure 2. Total monarchs reported and number of overwintering sites monitored for the Western Monarch New Year’s Count from Dec. 2016 to Jan. 2022.

 


These two counts are only possible because of the incredible regional coordinators and volunteers that spend countless hours surveying overwintering sites each year. THANK YOU to all who participate in this invaluable community science project!