Banded Waternakes (Nerodia fasciata) feed on frogs, tadpoles, and fish (Behler and King 1979).
Telford et al. (2001) described two new species of unicellular hemogregarine blood parasites from Nerodia fasciata pictiventris, Hepatozoon pictiventris and Hepatozoon fasciatae, both of which have a complex life cycle involving multiple hosts.
The Florida Banded Water Snake (Nerodia fasciata pictiventris) is the Banded Water Snake form that occurs in peninsular Florida. It is characteristic of shallow-water habitats throughout its range (Conant and Collins 1991).
The Florida Banded Water Snake is found from extreme southeastern Georgia through peninsular Florida to the southern tip of the state; it has also been introduced in Cameron County in extreme southern Texas (Behler and King 1979; Conant and Collins 1991). Behler and King (1979) note that the Florida Banded Water Snake (N. f. pictiventris) and the Banded Water Snake (N. f. fasciata) intergrade (blend together and become less distinct) in the Florida panhandle and southeastern Alabama.
The Florida Banded Water Snake is found in a wide range of shallow-water habitats in Florida, including swamps, marshes, flatwoods ponds, cypress bays, borders of lakes and ponds, and rivers (Conant and Collins 1991). Interestingly, Lawson et al. (1991) reported that they never found these snakes in mangroves, although they did find them in areas very close by, possibly because this snake's intolerance of high salinity prevents it from crossing the short stretches of salt water necessary to reach the mangroves.
The Florida Green Water Snake (Nerodia floridana) has a row of scales between the eye and lip plates. This scale row is absent in the Banded Water Snakes (Nerodia fasciata ). The very dangerous Florida Cottonmouth (Agkistrodon piscivorus conanti) may be difficult to distinguish from Nerodia species in the field. One good indicator of identity is behavior. Cottonmouths often stand their ground or crawl slowly away, while watersnakes usually flee quickly or drop with a splash into the water, although they also may defend themselves vigorously when disturbed (Behler and King 1979). A Cottonmouth may vibrate its tail when excited; a Water Snake will not. A highly aroused Cottonmouth throws its head upward and backward and holds its mouth wide open, revealing a white interior (the source of its name). Cottonmouths that are dead or otherwise safely approachable are easily distinguished from Nerodia Water Snakes by the presence of a facial pit between the eye and nostril; a vertical (rather than round) pupil; and a single row of ventral (belly) scales and single anal plate (rather than a double row and a divided anal plate in Nerodia). (Conant and Collins 1991)
The Florida Banded Water Snake (Nerodia fasciata pictiventris), like the other N. fasciata of the southeastern United States, has dark crossbands and a dark stripe from the eye to the angle of the jaw. It differs from the other named subspecies of N. fasciata in that it often has secondary dark spots on the sides of the body (between the prominent crossbands) and wormlike red or black markings across the belly. Coloration and pattern are highly variable, including black, brown, or reddish markings on a ground color of gray, tan, or reddish. In redder specimems, the black pigment is reduced or even lacking; in darker ones, black obscures the other colors, and virtually plain black specimens are not rare. Scales are keeled and divided. Young individuals have red or black crossbands that contrast strongly with a light ground color. At birth, Florida Banded Water Snakes are 19-27 cm. Adults reach 61-107 cm (record 160 cm). (Conant and Collins 1991)
In contrast to the freshwater Florida Banded Water Snake (Nerodia fasciata pictiventris), several Nerodia species or races have evolved a higher salinity tolerance that allows them to live in estuaries and salt marshes (N. clarkii clarkii, N. c. taeniata, N. sipedon williamengelsi) or mangrove swamps (e.g., N. c. compressicauda) (Conant and Collins 1991). Although it has sometimes been suggested that only a behavioral adaptation is necessary for these snakes to adapt to living in brackish water--specifically, a reluctance to drink salt water, which would kill them--Dunson (1980) investigated the physiological differences between freshwater forms such as N. f. pictiventris and those living in more saline conditions and found many differences in their physiology. Estuarine snakes were characterized by long survival times in sea water, low rates of net weight (water) loss, low rates of water influx and efflux (mainly dermal), low rates of sodium influx (mainly oral since the skin is impermeable), and low rates of sodium efflux even after salt is injected. In contrast, freshwater snakes, including N. f. pictiventris, exhibited short survival times in sea water, greater rates of net weight (water) loss, higher rates of water influx and efflux and much higher rates of net sodium uptake. Rates of water exchange in sea water seem to be low initially. Thus, Dunson argued that the high net sodium uptake causes an increased plasma osmotic pressure, stimulates thirst, and leads to drinking and a subsequently fatal dehydration. The apparent difference in drinking behavior of the freshwater and estuarine races of N. fasciata thus appears to be due to a difference in the net sodium uptake. Since this uptake appears to be oral it might be argued that drinking is indeed the root of the problem. However, further analysis shows that most of the water influx cannot be accounted for by drinking and must be dermal (i.e., occur through the skin) (Dunson 1980).
The Florida Banded Water Snake mates in January or February and in the summer bears 2-57 live young (it does not lay eggs) (Behler and King 1979).
A study in Everglades National Park found that many snakes, including Nerodia fasciata pictiventris, were killed by cars (Bernardino and Dalrymple 1992).
