Every spring, swarms of colorful butterflies called painted ladies can be spotted in Southern California as they make their way back to breed. Some years, the number of migrating butterflies is in the millions.
California is also home to painted lady populations that do not migrate and require food sources year-round. By documenting new nectar plants, scientists have renewed hope these butterflies may be resilient to climate change. There have been concerns that the butterflies are negatively affected by hotter, drier weather and habitat loss.
“The lack of rainfall in Southern California likely impacts the butterflies’ ability to move through the state, potentially decreasing nectar sources and causing them to die without reproducing,” said Jolene Saldivar, an ecologist at UC Riverside. “There’s so much to be learned about these butterflies before drought and climate change damage them irreparably.”
The research team sorted through 10,000 images of painted ladies in California shrublands. Any images in which the butterflies were not obviously feeding were omitted from analysis. The experts identified 195 new nectar plants as food sources for the species.
Of the top 10 plant species identified as food sources, seven are native to California. The butterflies also feed on showy ornamental plants common to California landscaping, such as lantana, butterfly bush and rosemary, as well as flowering weeds.
“Much of what we identified could responsibly be planted during a drought,” said study co-author Erin Wilson-Rankin.
Painted lady caterpillars consume plants, but they do not eat any agriculturally important species. They also serve as prey for insects, birds, wasps and reptiles, and mature butterflies can pollinate some of the many plants they visit.
“It might be getting tougher for painted ladies in some places, but these butterflies will feed on what flowers are available – even a few plants in a window box could help them,” said Wilson-Rankin.
Saldivar believes the results of this paper may encourage community scientists, whose contributions to knowledge should be celebrated and promoted.
The new identified food sources offer hope for imperiled butterflies.
“Adding a photo and a little information to a community science website or through an app on your smartphone might seem minor, but in the big picture, it helps inform us about ecological processes we’d otherwise be very challenged to learn about,” said Saldivar.
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