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 hundreds of volunteers, we have over 25 years of data demonstrating that overwintering western monarchs have undergone a >90% 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 (1997-2023) *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 1, 2023.

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

Results from the 2022 Western Monarch Thanksgiving Count:

Volunteers counted 335,479 butterflies at 272 overwintering sites in the West. Read our Blog and Press Release for complete summaries of the 26th annual Western Monarch Thanksgiving Count, which occurred November 12 – December 4, 2022.

Figure 1. Total monarchs reported and number of overwintering sites monitored for the Western Monarch Thanksgiving Count from Nov. 1997 to Dec. 2022.


Results from the 2022-2023 Western Monarch New Year’s Count:

The New Year’s count revealed a 58% seasonal decrease in the overwintering western monarch population, exceeding the typical range of 35-49% observed over previous winters. Read our blog for complete summaries of the 7th annual New Year’s count. 

Figure 2. Total monarchs reported and number of overwintering sites monitored for the Western Monarch New Year’s Count from Dec. 2016 to Jan. 2023.

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!