Data


The Western Monarch Thanksgiving Count

The Western Monarch Thanksgiving Count is a yearly effort of volunteer citizen scientists to collect data on the status of monarch populations overwintering along the California coast. Thanks to the extraordinary efforts of these volunteers, we have nearly 20 years’ worth of data demonstrating that monarchs have undergone a dramatic decline in the western U.S.

The data collected by volunteers are compiled and entered into the Xerces Society’s Western Monarch Overwintering Sites Database. You can download the count estimates for every year by clicking on the PDF link below. The graph is updated each year to reflect changes in monarch abundance at monitored sites over time.

Results from the 2016 Western Monarch Thanksgiving Count are now available!

Western Monarch Thanksgiving Count Data 1997-2016 

See our press release regarding the 2016 Western Monarch Thanksgiving Count.