Butterfly populations in Monarch Butterfly Grove in Pismo Beach have reached an all-time historic low this week with a total population of 2,000. In California, there has been an overall estimated decrease of 99.4 percent of monarch butterflies since the 1980s.
According to California State Park Interpreter Danielle Bronson, the monarch butterfly population in the Pismo Beach butterfly grove location is collecting population numbers lower than they have ever seen.
The count of 2,000 butterflies was conducted as recently as Monday, Jan. 14. The Pismo Beach location is the largest site in all of California.
While the numbers of butterflies have been decreasing over time, populations are lowered even further due to the recent storms and extreme weather conditions along the Central Coast.
“The current western population is 1 percent of its historic numbers,” Bronson said. “Eastern populations have seen a decrease, but not in a critical condition like we are in the western population.”
“In the ‘80s, we would see 250,000 butterflies,” Bronson said. “There is a multitude of reasons for the decrease.”
The reason for a decrease, estimated to be in the 80th percentile, cannot be pinned down to one specific causation, but a multitude of potential threats. Reasons vary from drought and lack of milkweed to unpredictable weather patterns, Bronson said.
The western population saw dramatic decreases in butterflies this summer, but official numbers from an annual Thanksgiving count were released by Xerces Society on Jan. 17, 2019.
The Pismo Beach Monarch Grove and Xerces Society are in partnership with the common goal of increasing butterfly populations across the western region. For more information on the western population of monarch butterflies, visit xerciessociety.org for statistics, resources and opportunities to donate.