By Stefanie Demong
It’s autumn in the Bay Area and this native butterfly is wearing all the right colors. Bay Checkerspots, of brush-footed butterfly descent, boast two-inch black wingspans dotted bright red, yellow and white.
This butterfly’s spots suggest its other big claim to fame. The insect’s checkerboard-like habitats inspired Paul Ehrlich’s theory of metapopulation. It was the checkerspots’ scattering across the Bay that led the infamous Population Bomb doomsayer to identify groups of spatially distant populations of the same species that may still interact.
Ehrlich began researching the commonplace checkerspots in the 1960s. At this time, there were many small, isolated patches of checkerspots in different pockets of the Bay–from Twin Peaks in San Francisco to the San Bruno Mountains in the west, to Mount Diablo in eastern Contra Costa County, and down into Santa Clara County, as far south as Hollister. Ehrlich found that these populations, sometimes connected by migration, endured periodic extinction and resurgence through recolonization–meaning, one group would move into the empty space left by another group’s demise.
Unfortunately, the Bay checkerspot population suffered a major decline starting in the 1980s. By 1987, they were officially designated an endangered species. Ehrlich’s specimens at the Jasper Ridge Biological Preserve went completely extinct by 1998.
Ecologists speculate that because checkerspots rely on native dwarf plantains (plantago erecta) as larvae hosts, any number of local stressors may be at fault. Climate change may alter the plantain growing season; ongoing construction of homes and highways, traffic exhaust or the use of pesticides can disrupt both butterfly and plantain growth; the arrival of invasive grasses has changed the soil composition.
The US Fish and Wildlife Service have led extensive checkerspot conservation efforts while Stanford University has backed studies on the species’ reintroduction to the Bay. Many believe that protected zones should be arranged in “stepping stone”-like pattern and proximity to encourage the intermingling behavior described by Paul Ehrlich. The hope is that someday, with careful practices and policies, checkerspots may once again grace the Bay Area.
Illustration and Photo Credits (from top): David Fierstein, The San Francisco Chronicle/Michael Maloney, KQED QUEST Flickr Set.
