Only 400 Western Monarch butterflies were counted at the Pismo Beach Grove during a recent survey—thousands less than usual. The low numbers in Pismo this year parallel a decline in monarchs around the state.
Western Monarch butterflies return to the same wintering sites each year, making it easier for the non-profit, Xerces Society, to count them.
This year’s early-season count recorded just 7,000 monarchs across all sites—a dramatic drop from last year’s mid-season count of over 230,000. The organization said fluctuations between early and mid-season counts are normal, but this year’s numbers are alarming.
Isis Howard, a conservation biologist with the Xerces Society, said record-breaking heat in California this summer and fall likely played a role.
“After a certain point, it's either too hot for them to survive, or it stresses them out so much that they become susceptible to other threats, like predation, viruses, parasites and diseases,” Howard said.
The effects of climate change, including prolonged heat and drought, pose a growing threat to monarch populations. According to Howard, this could harm the food chain by affecting other species that depend on monarchs.
“These butterflies and these pollinators and invertebrates end up playing a role in the web of life at large, so if we take away one species, there's oftentimes a ripple effect where it ends up impacting all these other native species that rely on that species for food, pollination services, etc.” Howard said.
Overall, the Xerces Society said that Western Monarch populations have declined by 90% since the 1980s.
According to the California State Park Foundation, monarch populations have fallen because of habitat loss, pesticides, disease and climate change. The group released data this week showing that preserving California state parks is crucial to protecting western monarchs.
People can also help out monarchs by using less pesticides and planting native milkweed.
The Xerces Society is currently conducting its mid-season count.
