I'm in total agreement with Clem. Laws that govern the shooting of ducks and other waterfowl have no bearing on the shooting of snakes. I would not carry a shotgun with birdshot for this task as you could potentially be accused of illegally hunting waterfowl. However, if you have a pistol with ratshot (lead) or a Judge that shoots .410 shells, then I think you would be perfectly within the law even though you are shooting lead.

"When there was no fowl, we ate crawdad, when there was no crawdad, we ate sand."

"YOU ATE SAND!" - Raising Arizona