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 25 years of data demonstrating that western monarchs have undergone a more than 95% decline 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 Count data for every year by clicking on the PDF or excel links below. The graphs of the Thanksgiving and New Year’s Count totals and monitoring efforts are updated each year in January and February respectively.

Results from the 2021 Western Monarch Thanksgiving Count are available!

Western Monarch Thanksgiving Count Data 1997-2021 in pdf and Excel. See our Blog and Press Release for the 2021 Western Monarch Thanksgiving Count.

*Note: If you are a researcher using this data, please be sure you periodically check back to make sure you have the most recent version of the data.

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

Graph showing the western monarch thanksgiving count totals and number of sites surveyed from 1997 to 2021.

Figure 1. Monarch abundance at the 283 overwintering sites in the West visited during the 2021 Thanksgiving Count, Nov. 13th – Dec. 5th, 2021.

 

Results from the 2021-2022 Western Monarch New Year’s Count are available below.

See our blog about the 2021-2022 New Year’s Count! This was the sixth annual New Year’s Count and volunteers visited a record number of sites. A total of 209 sites were surveyed, totaling 151,168 butterflies counted in the West. As shown in the graph below, 195 sites were monitored during both the Thanksgiving and New Year’s Count. The comparison between the two counts reveals an average decrease of ~38% over the winter season, which aligns with the trends we usually witness.

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 2022 is available in pdf and excel.

Data Citation: Xerces Society Western Monarch New Year’s Count. 2022. Western Monarch New Year’s Count Data, 2016-2022. Available at www.westernmonarchcount.org.

Figure 2. Monarch abundance at the 195 overwintering sites in California monitored for both the Thanksgiving and New Year’s Counts during the 2021 – 2022 overwintering season.

Previous years data:

2020/21: Click on the following links to read about the fifth annual New Year’s Count, see the graph, or check out the data in pdf or excel format.

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.