Adaptive management of the endangered Ohlone tiger beetle Cicindela ohlone (Coleoptera: Carabidae)

The Ohlone tiger beetle (Cicindela ohlone) is an endangered species endemic to Santa Cruz County, California. As with all tiger beetles, C. ohlone requires bare ground for efficient foraging as well as for oviposition and larval growth and survivorship. Extensive bare ground is a feature of the historic coastal grasslands in which the Ohlone tiger beetle evolved. Threats to the Ohlone tiger beetle include loss of its coastal terrace grassland habitat to development, invasion of exotic annual grasses and lack of disturbance that maintains bare ground. Management of C. ohlone habitat has been inconsistent throughout its range and it is unclear what practices best enhance C. ohlone populations. While frequent burning and grazing seem to maintain at least some bare ground, populations of the Ohlone tiger beetle continue to decline. Here, we tested scraping and soil decompaction as management techniques to enhance the Ohlone tiger beetle habitat. In April 2009 we created three blocks of six plots each with two plots in each block randomly treated as either scraped only, scraped and ripped, or scraped and ripped and tamped. All treatments were done using a front loading tractor. The blocks were created in 3 different sites: one with C. ohlone present, one where C. ohlone had been absent over the last two years, and one where C. ohlone has not previously been found but near other habitat patches. All plots were monitored for vegetation, C. ohlone adult activity, and larval burrows during winter and spring of 2010.