In the night we went to a shop nearby to buy eggs. On the way back, Esme suddenly stopped, walked a bit back and looked on the ground. And there is was, a very little snake. The animal was dark green colored, olive, with a yellow band around its neck. Since I have been talking about having a snake as a pet ever since I am in Mexico, I decided to take the animal back home.
I put my hand down close to the animal, and it moved onto my hand. It had an ant attached to its mouth, but looked more like the ant was attacking it, instead of the snake having "cenar" (dinner). Esme had emptied one of the plastic shopping bags and I put the snake inside it.
Back home, I entered "snake yellow small" into Google's image search. Some time ago I was able to identify a bird we saw in a similar way. The "blue bird mexico" turned out to be a blue crowned Motmot. And we were lucky, the third picture in the result looked a lot like the snake we had found, a ringneck snake (Diadophis punctatus subspecies), a harmless colubrid snake.
So I used Google a bit more to read about this little snake. It is active at night, which sounded very good to me, since it means it doesn't need special light. Since my pet scorpion "Tina" died mysteriously a few months ago I could reuse the terrarium for the ringneck snake.
Also the food requirements looked easy: small worms, small insects, etc. And the current contents of the terrarium sounded like the perfect habitat, damp mulch for substrate and pieces of wood to hide under during the day. We decided to clean it the next day and put the snake in a plastic container with pieces of dead leaves to hide under until tomorrow.
Some people might object to taking a snake from the wild. However, had we let it on the sidewalk it might have been killed just because it's a snake. Also, since the snake is clearly a juvenile, it might get used to live in a terrarium. I have seen snakes in a local pet shop and I somehow have the feeling they have not been bred in captivity, but are caught in the wild. I also decided if the snake doesn't eat within two weeks, I will let it go. Since I know its current habitat, I know where it can be released.
Finally, I am not going to handle this snake unnecessary. I understand that this is not a pet like a cat. Lifting it, touching it, only gives it stress.