Tigers on Market Street



Tigers on Market Street: A Remarkable Story of Adaptation for San Francisco’s Largest Butterfly
A project by Amber Hasselbring and Liam O’Brien

Seedfund Proposal: The phenomenon of the Western Tiger Swallowtail (Papilio rutulus) and its behavioral adaptation to Market Street was first noted by lepidopterist Harriet Reinhard in 1987. During the 1960’s and 70’s the London Plane Tree (Platanus X acerifolia) – one of the butterfly’s larval food trees – was planted en masse in the heart of the City. In combination the trees, canyon of tall buildings, dappled sunlight, and the presence of underground water, an unexpected habitat was created. The butterfly’s story is 75% known: males and females fly above the canopy looking for mates, females lay eggs on the leaves, caterpillars feed on foliage and pupate, and adults emerge in spring to repeat the cycle. The butterfly overwinters as pupa attached to tree bark.

Featuring this butterfly’s story could have ramifications for urban planners worldwide. We as a species have a history of changing the natural world too quickly for most creatures to adapt. The uniqueness of a 40-year-old urban forest of London Plane Trees and the presence of this butterfly despite hostile conditions provides a controlled setting for observation. The more we understand about the creatures that have moved in, the better we can provide what’s missing in the unnatural habitat and further mimic their natural habitats. Our observations, in kind, can be advanced and utilized by future planers and can represent seismic shift in the paradigm of urban planning.

Simply put, the goal of this proposal is to flush out the unknown aspects of this phenomenon so we can accurately inform the Better Market Street team with habitat enhancements for City’s most prominent street. Tigers on Market Street is gaining traction with the BMS team: SF Planning, SFDPW and CMG Landscape Architecture have begun to pay attention. Ruth Gravanis, Commissioner on the Environment and Peter Brastow, Biodiversity Coordinator with SF Environment are also key public supporters. With our allies help, we would assure that our conclusions would be incorporated in the vision for Market Street.


Fieldwork & Research Summer 2013:

  • Walk established transects along Market Street from Civic
  • Center to Ferry Building to observe the butterfly’s bivoltine life
  • cycle (two distinct flights/generations per year)
  • Rear eggs and caterpillars from larval food
  • for parasitic inventory
  • Inventory, collect and catalog
  • additional entomological specimens
  • Survey the use of additional larval food trees already present
  • downtown
  • Observe present nectar and water sources downtown
  • Approach professors Barbara Holzman, PhD & John Hafernik, PhD of SF State University about including entomological interns

Field Guide: The culmination of data from these six months would be incorporated into either an illustrated poster or field guide that we would present to BMS and private entities. Illustrations of species would be based upon collected specimens.  Grounded in the adage that the first moment in stewardship comes from discovering and learning the names of the creatures around us, this project equally highlights educational and artistic interventions. Hasselbring and O’Brien bring a history of art and illustration to the project. The exact outcome of this component is still to be determined.