PACIFIC GROVE — Monarch butterfly numbers are down this year entering prime counting season, but experts aren’t panicking yet.
“Butterfly populations are bouncy,” said Isis Howard, an endangered species conservation biologist at the Xerces Society. “The monarch butterfly life cycle is unique in that they have multiple generations present at one time. The super generation’s success is reliant on the previous generation’s success.”
And with last year’s winter storms, she says it likely impacted the breeding population of monarchs, hence the lower numbers. Animals can behave differently year after year, meaning there may be more on the way. “It’s a little early to tell. There might always be a late wave of monarchs.”
The western monarch butterfly is the species that earned Pacific Grove the name of Butterfly Town, U.S.A. Unlike the eastern monarch butterfly, they migrate between northern states like Washington, Oregon, and Idaho before coming to roost in temperate California for the winter. At temperatures below 55 degrees, monarch butterflies cannot fly. Instead, they huddle together in orange and black clusters in the trees until the air warms again. This unusual behavior makes it possible to count them early on cold winter mornings, when they’re still gathered together.
The annual Thanksgiving count is vital for those who want to ensure the preservation of these butterflies, which are set to be listed as “endangered” by the IUCN Red List of Threatened Species. “By comparing how that number differs throughout the years, we’re able to get a very good idea of how the population is faring over time,” said Natalie Johnston, community science coordinator at the Pacific Grove Museum of Natural History. “And then we can start working on what factors contribute to this and what needs to be done in order to have that future population.”
But across the monarch butterfly sanctuaries in Pismo, Natural Bridges and Pacific Grove, the volunteers have noted far fewer butterflies overall. The monarch butterfly count on the Pacific Grove Museum of Natural History, which is updated weekly, currently lists the count at 7,604. Johnston reported that’s far less than the 12,600 butterflies that they counted last year around this same time. Major concerns about how low the numbers had dropped in 2020 were starting to be alleviated when the numbers climbed last year – but this might just be a low year.
The Xerces Society, a conservation group focused on invertebrates, also conducts another butterfly count in January to obtain further data on how monarchs are doing. Earlier this year, they reported a 58% average decrease of monarchs — according to the Xerces Society’s conversations with local volunteers, it was likely due to the rain and wind causing trees to topple, with monarchs still roosting in them. But in Pacific Grove, Johnston noted the populations had far more success. There was only a 17% decrease, which is an average and expected decrease in the area. Johnston speculates that the variety of trees in the area may have had something to do with it. “We have eucalyptus, Monterey pine, and Monterey cypress… it may have something to do with the variety of trees to provide more robust habitats for the monarchs.”
That’s not to say monarchs shouldn’t be a focus of our attention. Their populations have declined by approximately 95% since the 1980s. Howard and Johnston both said people can advocate for these butterflies by educating themselves on local action. For areas further inland, like Carmel Valley, Johnston recommends planting native milkweed species and other plants that monarchs can eat during their breeding and overwintering seasons — which means they need to be pesticide-free to be safe for butterfly consumption. In other areas, ensuring that there are habitats for monarchs in the form of native trees can also help. Check with your local experts to find what specific actions you can take.
And while you might not want to be one of the 12 volunteers in Monterey County who gets up in the wee hours of the chilly morning to count butterflies, you can still learn about them at the Pacific Grove Museum of Natural History. On Saturday, their Science Saturday event is all about monarchs. They’ve even got a monarch butterfly-themed cover band called The 5 M’s, made up of interpreters from the Natural Bridges site.
“I love the fact that Pacific Grove calls itself Butterfly Town U.S.A.,” Johnston said, “and I would love to see more butterfly and nature stewardship, and for that to be an identity — not just at Pacific Grove, but for all the residents of the Monterey County area.”