Ran into this little fella (but not over him) riding on the trails around Mosquito Lake on Saturday.
Snake expert, Leslie Anthony, identified him for us as a Valley Gartersnake (Thamnophis sirtalis fitchii), a subspecies of the Common Gartersnake.
The lowly Garter Snake plays an important role in energy transfer from aquatic to terrestrial ecosystems. Hence, anyone hacking them up with a shovel might be considered an environmental terrorist. The one most familiar in Whistler is a subspecies of the Common Garter Snake, Thamnophis sirtalis fitchii, dark colored with a bright, mid-dorsal yellow stripe and, along its flanks, at least faint lateral stripes as well as regular red splotches. The scales are strongly keeled. You’ll see this species everywhere although it tends to like wetlands and adjacent habitat. Small ones eat worms and large ones scarf almost anything but prefer amphibians.

