Each year, during a three-week period around Thanksgiving, scores of volunteers fan out through coastal California to find and count overwintering monarch butterflies as part of the Western Monarch Thanksgiving Count. The results are eagerly awaited, as the count provides the best estimate of how well this beloved butterfly is doing. We’re reaching the end of the 2018 count period, and while we do not have all the data in yet, the count numbers that are coming in from volunteers, regional coordinators, and Xerces staff who traveled to California overwintering sites are disturbingly low.
Going into the overwintering season, we were not expecting this to be a great year because we knew it had been a rough season in the breeding and migratory range (read more about this in Xerces’ recent blog here). It’s worse than anyone had anticipated, however, with early count numbers showing that the population is down an order of magnitude from last year, which was a low population year itself. We currently have preliminary count results from 97 sites, which includes many of the most important overwintering sites. In 2017, these sites accounted for 77% of the total monarch overwintering population, hosting approximately 148,000 monarchs. In 2018, the same sites have only 20,456 monarchs. This represents an 86% decline since last year. Continue reading this blog here….