The Ohlone Tiger Beetle (OTB) (Cicindela ohlone) holds a distinct place as a federally endangered species endemic to the coastal mid-Santa Cruz County area in California. Its habitat is characterized by clay-based marine terraces, specifically the Watsonville loam soil, supporting native grassland remnants. Decades of land conversion for development and the changing conditions of the remaining grasslands have driven the OTB to the brink of extinction.

How do we help conserve and recover the species? Conservation grazing plays a pivotal role. The Beetle Pasture at Glenwood Open Space Preserve in Scotts Valley is a priority management area where strategic grazing optimizes benefits for the OTB while minimizing impacts on native grasses. The grazing takes place when herbaceous plant growth is rapid or exceeds target levels—thus helping to maintain a balanced system. To protect buried OTB eggs during heavy winter rainfall, grazing is excluded. We are using our understanding of the distribution of Watsonville loam soils to guide future habitat management efforts and safeguard the OTB’s unique habitat within the Beetle Pasture.

In addition to maintaining the OTB habitat using cattle grazing, we monitor two stages of the OTB’s lifecycle- larvae and adults in hopes of increasing the numbers and expanding the range of the Glenwood population. The females lay eggs from mid-January to mid-May. Tiny larvae emerge, constructing shallow burrows in the ground where they spend several months thermoregulating and molting through three instars (stages in the life of an arthropod between two successive molts). The larval burrows, ranging from 1.5-6 mm in diameter and 10-20 cm in depth, provide a safe space to ambush prey, which consists primarily of ants.

In July 2023, the Land Trust Stewardship Team conducted their annual survey for larval burrows in the Beetle Pasture at the Glenwood Open Space Preserve. Utilizing ESRI's Field Maps Application, they mapped the locations of OTB larval burrows, providing valuable data for population analysis.

This survey area covers an approximate 3-acre region in the southwest portion of the preserve, characterized by level clay loam soil and bare ground patches—precisely the habitat the OTB favors. These surveys extended beyond the known occupied area to potentially suitable habitat, ensuring a more comprehensive understanding of the species' distribution.

Over the years, the area occupied by larval burrows has fluctuated, underscoring the need for continued monitoring and conservation measures. While the numbers of burrows were significantly better this year than last (238), they are still below the 21-year average (499). As we strive to safeguard the OTB, it is evident that these burrow surveys provide crucial insights that will inform conservation strategies. Collaboration and informed conservation practices are essential to ensure the survival of this rare and endangered species within its limited geographic range.