Western Monarch Thanksgiving Count Graph
This graph shows population censuses of western monarchs that overwinter at more than two hundred groves along the California coast from 1997-2013. Volunteers with the Western Monarch Thanksgiving Count have contributed the population estimates displayed above. The western monarch population consists of several hundred thousand butterflies, on average, although a peak number of 1.2 million butterflies were counted in 1997. Monitoring of the western population over a 17-year period shows a significant decline in both the total number of butterflies reported per year and the average number of monarchs per site. Western monarch population estimates from the Fall of 2013 only represent 50% of the 17-year average (Monroe et al. 2014).