I have been noticing butterflies in the park lately. This Anise Swallowtail (Papilio zelicaon) was flitting around a patch of yarrow and sticky monkey flower near the reservoir above the falls on Strawberry Hill this past week, while I was busy sketching a Red-tailed Hawk. Then it perched for a long time, so I snapped a picture and drew this from the photo later. I find that drawing fixes the markings in my memory much more permanently than taking a photograph; now I will definitely recognize an Anise Swallowtail next time I see one. There are about 35 species of butterflies in San Francisco, listed by local lepidopterist Liam O’Brien on his website: http://sfbutterfly.com/www.sfbutterfly.com/SF_Index.html
I also own the wonderful Field Guide to Butterflies of the San Francisco Bay and Sacramento Valley Regions, by Art Shapiro, illustrated by Timothy Manolis, which has a long and informative introduction explaining butterfly life cycles, behavior, population dynamics, effects of climate change, plant associations and much more. From this book I learned that the Anise Swallowtail is a fascinating and adaptable butterfly!
The species Papilio zelicaon has been remarkably flexible in response to dwindling numbers of native plant hosts that once sustained it. It is found throughout the temperate Northern Hemisphere, but there are many “ecological races,” meaning localized populations that have adapted to different ecotypes. Its common name reflects the fact that it long ago adapted to breed on naturalized non-native species of the carrot family (i.e. “weeds”), particularly sweet fennel (anise). Fennel was already in California by the Gold Rush and Anise Swallowtails were observed feeding on fennel here in 1850 by the French forty-niner Pierre Joseph Michel Lorquin (California’s first recorded lepidopterist). Fennel grows abundantly along roadsides and in vacant lots, sustained by runoff from urban roads and back yards, and it affords edible material year round. Anise Swallowtails that rely on fennel are multivoltine, meaning they go through the lifecycle multiple times during the year. But in areas where there is little or no fennel and they breed on other plants, they may have only two life cycles per ear (bivoltine) and even just one life cycle per year (univoltine) in serpentine areas in the Coast Ranges (e.g. Napa County). This is a surviver species!
I think the butterfly I saw was probably a male, “hill-topping.” Just hanging out there in a sunny, late afternoon, exposed spot, looking beautiful and sexy, hoping to attract a female. I didn’t detect the scent of pheromones, but then I’m not a butterfly.