“Every year in late summer and early fall, western monarchs journey back to more than 200 overwintering sites up and down the California coast. Here, they gather by the dozens, hundreds and even tens of thousands to rest for the winter, before mating in the spring and starting the cycle all over again” (Xerces 2016).

Since 1997, a dedicated team of citizen scientists has monitored these overwintering groves each year, estimating population numbers and gathering information on habitat condition, through the Western Monarch Thanksgiving Count, which takes place for three weeks around the Thanksgiving holiday. This effort has revealed that monarchs at California overwintering sites have undergone a 74% decline since 1997 (Xerces 2016).

• Xerces Society for Invertebrate Conservation. 2016. Western Monarch Count Resource Center. Consulted online 11 April 2016 at: westernmonarchcount.org/.

Keywords: citizen science, overwintering, western monarchs