Effects of off‐highway vehicles on sandy habitat critical to survival of a rare beetle

Recreational activity, including use of off‐highway vehicles, threatens a variety of rare taxa that depend on undisturbed marine beaches, freshwater shorelines, aeolian dunes and other sandy habitats. The endemic Coral Pink Sand Dunes (CPSD) tiger beetle (Cicindela albissima Rumpp) occupies a 300 × 1500 m area within a larger dune field in southwestern Utah. Our objectives were to determine the habitat required by larvae, explain why habitat is so restricted, and to quantify how off‐highway vehicles (OHVs) affected habitat. Macrohabitat characteristics (subsurface moisture, sediment grain size, compaction, vegetation cover) were not different in areas containing high beetle densities compared to those with low. Within the core area containing most beetles, larvae were found primarily in microhabitats with cohesive sand close to the surface. Compaction and moisture provide the cohesive sand required for larvae to maintain burrows during development. Compacted sand, soil moisture and vegetation supporting larval prey were largely absent in heavy OHV‐use areas. Larvae were less abundant within OHV tracks compared to non‐track areas. Apparent survival of larvae experimentally translocated to OHV tracks was lower than that of larvae translocated to non‐OHV areas. Our results show that beetles are restricted to an area where cohesive sand occurs near the surface, interspersed with sufficient vegetation to produce prey. These conditions are localised to an area where dunes migrate at a rate sustaining these conditions. Restricting OHV use from all areas where natural processes create cohesive sand covered with adequate vegetation will minimise extinction probability for the beetle.