Butterflies in Residence Hedge Against Climate Change?
While monarch butterfly numbers at traditional winter roosts on the California coast hit an all-time low of about 2000 last winter, citizen-science observers have noticed that some remain in the San Francisco Bay Area year-round. Biologists Elizabeth Crone (Tufts University) and Cheryl Schulz (Washington State University) estimate a resident population of 12,000 in northern and central California, extrapolating from a Berkeley survey. Resident monarchs may provide a hedge against extirpation, but pathogens may spread from residents to migrants. The shift could reflect warmer and drier conditions or increased fall and winter availability of tropical milkweed and other food sources. It’s not unprecedented: monarchs have dispersed to Western Europe and North Africa, the Caribbean, and the South Pacific, and most of those populations don’t migrate.
Climate effects on either the decline of the migrants or the recent behavioral change are hard to verify. “We can’t tell just from the data we have now whether it’s land use or climate change that’s driving the decline,” Crone explains. “There’s a stronger correlation with the development of land along the coast and the use of pesticides.” California’s recent wildfires have been proposed as a factor; while data is lacking, she thinks that’s worth investigating. The US Fish & Wildlife Service hasn’t reversed the Trump administration’s refusal to list the monarch as endangered, and a court decision last year excluded insects from protection under the California Endangered Species Act. Meanwhile, gardeners can help by planting monarch chow. “Adult monarchs need more than milkweed,” Crone notes. “They need a lot of different nectar plants to enable them to fly farther, live longer, and lay more eggs.” While recommending native milkweed if available, Crone says the jury is out on tropical milkweed: “We don’t know if it’s good or bad. I wouldn’t encourage people to pull it up, but many other conservationists would.”
Other Recent Posts
Methane, a potent greenhouse gas, leaks from abandoned wells across the country. Curtis Shuck has been finding them by hand, well by well. But finding the leaks is where satellites and citizens come in.
Imprisoned with Climate Change
Climate change has a disproportionate impact on incarcerated Americans. Juan Moreno Haines, one of 2.3 million prisoners in the US, describes his experience.
Artists Circle Confronts Climate Displacement and Just Recovery
The climate crisis in driving the displacement of people around the world. In the midst of the pandemic, an artists circle began developing new approaches to the issue.
Oona Khan dreams about her home of the future, after losing her Malibu retreat to fire. Caught in a quagmire of legal battles with Southern California Edison, and surging construction costs, Khan is still waiting to start construction.
The Case for Climate Castles
As climate change throws more extreme events at us, isn’t it time to think bigger, bolder, further ahead? Six young architects draw climate-resilient castles.
Looking for Justice at the Nexus of Housing and Climate Policy
How housing is built and who it is built for are not only equity questions, but also climate mitigation questions. When people can afford to live near their jobs, their emissions from commuting go down.
Bittersweet Beach Outing to See King Tide
On a clear morning in January, a group of tide worshippers gathered at the Santa Monica Pier to “celebrate the ocean and build our climate community,” said Laurene von Klan.
Safer at School from Wildfire Smoke?
Research confirms the drastic impacts wildfire smoke has had on school learning. But 16 East Bay schools now have updated air filters and more actions are in the pipeline statewide.