San Francisco Gartersnake - San Mateo County, California. Listed as endangered by the state and by the federal government. The habitat of this snake has declined severely due to urban development and agricultural land use and altering of the waterways needed by this snake. Some authorities believe that the remaining fragmented populations of this snake could be further threatened by overcollecting for the pet trade. San Francisco Gartersnakes are popular pets in Europe, where it is possible that there are more of these snakes than there are in the wild in California.