Data


The Western Monarch Thanksgiving & New Year’s Counts

The Western Monarch Thanksgiving and New Year’s Counts are the product of annual monitoring efforts by volunteer community scientists to collect data on the status of monarch populations overwintering along the California and Northern Baja, Mexico coast (and a few sites from inland areas of California and Arizona). Thanks to the extraordinary efforts of these volunteers, we have 24 years of data demonstrating that monarchs have undergone a dramatic 99.9% decline in the western U.S. since the 1980s.

The 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.

You can download the Thanksgiving and New Year’s data for every year by clicking on the PDF or excel links below. The graph of Thanksgiving count totals and monitoring effort is updated each year.

Results from the 2020 Western Monarch Thanksgiving Count are available!

Western Monarch Thanksgiving Count Data 1997-2020 in pdf and excel

*Note: The 2020 Thanksgiving Count data was revised with new count data from volunteers on 2/16/2020.

Data Citation: Xerces Society Western Monarch Thanksgiving Count. 2021. Western Monarch Thanksgiving Count Data, 1997-2020. Available at www.westernmonarchcount.org.

See our Blog and Press Release for the 2020 Western Monarch Thanksgiving Count.

Click here for a larger version.

Results from the 2020-2021 Western Monarch New Year’s Count are now available!

See our blog about this years New Year’s Count! This was the fifth annual New Year’s Count and volunteers visited a record number of sites! A total of 149 sites were surveyed during both the Thanksgiving and New Year’s Count! 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 that participate in this invaluable community science project! The data from 2021 is available in pdf and excel.


Figure 1. Monarch abundance at the 149 overwintering sites in California visited during both the Thanksgiving and New Year’s Counts during the 2020 – 2021 count season.

Previous years data:

2019/20: Click on the following links to read about the fourth annual New Year’s Count, see the graph, or check out the data in pdf or excel format.

2018/19: Click on the following links to read about the third annual New Year’s Count, see the graph, or check out the data in pdf or excel format.

2017/18: Click on the following links to read about the second annual New Year’s Count, see the graph, or check out the data in pdf or excel format.

2016/17: Click on the following links to read about the first New Year’s Count or to see the data in pdf or excel format.