Banded Water Snake vs Moccasin

Since my family bought this house, we have had a small population of Banded (or Florida) Water Snakes, Nerodia fasciata pictiventris, living in the swamp and by the river. People frequently think they are moccasins and panic, but these guys are totally harmless and very docile- their main defense is to exude slimy, stinky musk on your hands when caught. The main difference is the shape of the head and neck, the pupil shape and whether they are heavy bodied. See the chart below from the U.F. Wildlife-Johnson Lab for more details. Granted, you may not want to get close enough to notice these details-but, unless the snake is actually attacking you- err on the side of caution and please leave it alone. I am attaching photographs of one of our resident Banded Water Snakes, he was in full molt so his coloring is darker and less detailed than after he molts, and his eyes are hazed over, but he was very easy to catch in this condition.
 
 

 Link to full article with images- http://ufwildlife.ifas.ufl.edu/water_moccasin_watersnake_comparison.shtml

Harmless Watersnake or Venomous Water Moccasin?

There are many harmless watersnakes (genus Nerodia) that are frequently confused with venomous Water Moccasins a.k.a. Cottonmouths (Agkistrodon piscivorus). Sadly, harmless snakes are often killed out of fear for the safety of family and pets. Most people, even those who aren't afraid of snakes, would feel safer if they knew how to rapidly identify snakes near water as harmless or venomous. So how can you tell them apart?

	Harmless Watersnake	Venomous Water Moccasin
Usually found near water?	YES	YES
Body shape is...	SLENDER	HEAVY
Body dark, often with bands?	YES	YES
Rough-looking, keeled scales?	YES	YES
Head shape is...	SLENDER or FLATTENED	THICK, BLOCKY
Neck is...	NOT DISTINCT	NARROWER THAN HEAD
Dark facial band or eyestripe?	MAYBE	YES
Eye pupil type is...	ROUND	VERTICAL
Heat-sensing pits on face?	NO	YES