http://monarchalert.calpoly.edu/index.html
"Monarch Alert Project
The monarchs, butterflies that overwinter in California can number in excess of 100,000! Populations of western monarchs are known to fluctuate from year to year. Monarch Alert is a citizen based research project backed by graduate student researchers and faculty from Cal Poly State University, San Luis Obispo. We focus on the demography and population fluctuations of western monarch butterflies, through sampling of overwintering populations in San Luis Obispo and Monterey Counties."