This adult Pacific Gopher Snake (Pituophis catenifer) moved in fits and starts, more hesitatingly than its usual fluid slither, and it used its tongue constantly. The reason was probably the stiff westerly wind blowing without shelter atop the little hill on the northwest corner of the park, where the Peace Symbol lies. Snakes don’t have great vision. They rely heavily on their sense of smell. They smell not only with their nose but very much with their tongue. The tip of each fork of the tongue has highly sensitive collectors for chemical molecules in the air or on the ground. With each flick of the tongue, the snake collects a sample of those chemicals and brings them into its mouth where they’re transferred to the snake’s vomeronasal organ and analyzed by the brain. Having two extensions of the tongue lets the snake smell in stereo. Tiny differences in the strength of chemicals tell the snake whether a smell is coming from the left or the right, much as tiny differences in sound allow our ears to determine the source of a sound. Sensing odors is tough in a brisk headwind. I think that accounts for the animal’s halting motion. Note that the snake constantly sampled not only the air but also the ground in front of it. It was probably following a familiar trail leading to an opening in its burrow. The snake’s efforts were successful. Despite the wind, it found its hole somewhere under the park bench on the north side of the hill, and disappeared.
As I’ve written here several times, gopher snakes are not venomous and they don’t attack people. They mostly eat tiny rodents, of which the park usually has an ample supply. When you see one, don’t be afraid. You can even be helpful sometimes if you see one on the pavement by warning bicyclists to avoid it.
There’s neat material on the history of people’s ideas about forked tongues in the sources below. One philosopher believed the forked tongue was good for cleaning out the snake’s nostrils. Shakespeare and others believed that the tongue was a stinger. It’s only recently that scientists have figured out that the tongue was an organ of smell.