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APPENDIX I - BIOLOGICAL RESOURCES Giant Garter Snake (Thamnophis couchi gigas) State Listed: Threatened; Federal Listed: Candidate 2 The giant garter snake has a historic range that includes the survey site. This marsh and backwater reptile once thrived in the many natural sloughs and meandering side channels of the Delta river system. Confinement of the great rivers to high-banked levee systems has greatly reduced this reptile's numbers. The more heavily vegetated portions of the permanent pond shore along with segments of the inshore zone of the Mokelumne River appear to offer potential habitat for this reptile. An initial population survey shows three population sites within ten miles of the project area (Hansen, 1986). These are located near the Consumnes River and with its connection to the Mokelumne River west of the project area, form a potential movement corridor to the Tracy Lakes site. A spring survey during prime thermal periods for diurnal snake activity would be needed to provide definitive status information on the giant garter snake at this site. Other Protected Species Two protected amphibian species that most likely existed on the site in recent time are the red-legged frog (Rana aurora) and the California tiger salamander (Ambystoma tigrinum californiense). They are both pond spawning species. Ideal conditions for the red-legged frog is a permanent pond with lush shoreline cover. The tiger salamander will spawn in temporary ponds with barren shorelines, but must have nearby retreat sites in the form of rodent burrow systems, in which to estivate during the hot, dry months. Given the need for a permanent pond habitat and the large population of bullfrogs now present at the permanent pond on the site, it is unlikely the red-legged frog exists on the site. The California tiger salamander, however, requires only a seasonal wetland pond for spawning and larva rearing. The latter usually metamorphose by late May or early June when they usually leave the pond site and seek estivation sites in the form of rodent burrows. The seasonal pond wetland afforded by Tracy Lakes would provide a most suitable spawning habitat during medium and high rainfall years. Because this type of salamander can skip several breeding seasons when rainfall on a given year is too light to fill seasonal wetland depressions, the possibility exists that the California tiger salamander may be present. Three protected invertebrate species are known to exist in the greater project site area. The curved-foot Hygrotus diving beetle (Hygortus curvipes) and the vernal pool fairy shrimp (Branchinecta lynchi)prefer natural pond and spring pool conditions. Only highly disturbed stock ponds and a small reservoir stocked with fish are located on the site. Dip net sampling in these failed to produce either species. The valley elderberry longhorn beetle (Desmocerus californicus&morphus), a federal-listed threatened species, occurs in San Joaquin County where elderberry plants (Sambucus sp.)comprise part of the local riparian community. Several stem sections were closely examined for signs of the beetle larva, but none 20