A Comparison of Desert Tortoise Populations along the Kern River Pipeline Right-of-Way 1991-2003

摘要

The desert tortoise (Gopherus [=Xerobates] agassizii) is a federally threatened species that occursthroughout the Mojave Desert. The Mojave population of the desert tortoise has been decliningin much of the region due to both direct and indirect human caused mortality. The original KernRiver Pipeline was constructed in spring and summer of 1991. In the fall, winter, and spring of2002 and 2003, the 2003 Expansion Project was completed which looped 320 miles of the exist-ing Kern River pipeline system in the Mojave Desert in southern Utah, Nevada, and California.Data collected from field surveys and monitoring during the course of each construction projectallows a unique look at the evolution of tortoise populations in the vicinity of the pipeline ROW,inclusive of a number of areas designated as critical desert tortoise habitat. Both projects requiredextensive desert tortoise monitoring as part of construction. Data collected during both construc-tion projects were collected to evaluate population trends and activity levels along the entirepipeline ROW. Based on the findings, the extent of tortoise activity appears to have decreased inthe project area. Tortoise encounters were significantly reduced during the winter constructionseason utilized by the 2003 Expansion Project, supporting an agency preference for constructiontiming. This information can be used as a tool by regulatory agencies and project sponsors in thefuture planning, establishment of realistic mitigation requirements and protection for the deserttortoise.