THE NORTHERN WATER SNAKE ALONG THE CONNECTICUT RIVER
For inquiries contact Thomas F. Tyning, Herpetologist, Massachusetts Audubon Society
Water moccasin it isn't! No doubt the many tales of large, venomous snakes clinging
to overhanging vegetation along the banks of the Connecticut River are attributable to the
heavy-bodied, but non-venomous water snake (Nerodia sipedon). There are no water
moccasins anywhere near the Connecticut River, nor anywhere near New England, nor
anywhere near the northeastern United States. The true water moccasin (Agkistrodon
piscivorous) is an animal of the lower Mississippi River valley and the southeastern U.S.
The farthest north it gets is the southeastern corner of Virginia, and it is not common
there. So, why do so many people who live near the Connecticut River believe we have
water moccasins living here? I don't know. We're more likely to get a polar bear
swimming across the river than a water moccasin.
There are two venomous (and endangered) snakes still found in remote parts of the
southern Connecticut River valley: the timber rattlesnake (Crotalus horridus) and
northern copperhead (Agkistrodon contortrix), both of which only very seldom visit the
edge of the river and are likely never to be seen by people. There are a number of aquatic
or semiaquatic species that are often referred to as "water" snakes. But in their inimitable
blandness, herpetologists have decided to retain the most boring common name for one
fascinating animal properly named the Northern Water Snake (Nerodia sipedon). There
are closely related water snakes (all in the genus Nerodia) in other parts of the country.
For example, visitors to Georgia and Florida commonly encounter both Brown water
snakes (Nerodia taxispilota) and the Green water snake (Nerodia floridana). Our local
northern water snake has a wide distribution, getting as far west as Colorado and as far
south as north-eastern North Carolina. There are several recognizable subspecies,
including the unique Lake Erie water snake (Nerodia sipedon insularum), the Midland
water snake (Nerodia sipedon pleuralis), and others. Our Connecticut River northern
water snake subspecies is designated Nerodia sipedon sipedon. If you have some early
snake guides, water snakes were once in the genus Natrix.
The highly variable outward appearance of water snakes does not help us identify them
with ease. Most often adults take on a somber coloration, often coated with the fine silt
that covers much of the open riverbanks where this snake basks in the sunlight.
when swimming is the wonderful banded pattern that most adult snakes have readily
apparent. Young water snakes are strongly patterned with dark crossbands on a light
body. This contrasting design may afford neonates some cryptic, passive defense because
as they age water snakes develop increasingly less contrast.
Large adults can appear
totally dark brown or black. At all ages, water snakes possess an incredibly beautiful
pattern on their bellies unusual for most snakes.
A mix of red, yellow, tan and/or brown
half moons, blotches, and dark patches can be vibrant. What is the possible function of an
impressive mix of colors and shapes on a snake's belly? I'm not sure, but it is obvious
that water snakes spend a great deal of time swimming often at the surface and an
aquatic predator-eye's view may find the snake's outline more difficult to determine.
When seen from below, the light and dark swirls on the rippled surface of the Connecticut
River may, in fact, turn a northern water snake's body into a complex and
indistinguishable form. Since they can be active at night, especially during the heat of the
summer, their belly pattern may also make them all but invisible to potential prey.
Mainly feeding on frogs, small fish, crayfish, insects, and occasionally small mammals,
northern water snakes find nearly everything they need within a few meters of the river's
edge. Good areas to search for them are where open, sunny banks allow for basking, a
thick tangle of vegetation in which to conceal themselves, overhanging banks where they
can take refuge or hunt, and the presence of burrows, rock crevices, or beaver lodges in
which to spend the winter. Here in New England, water snakes do not appear much
before the first of April and seem to all but disappear by early October. Prolonged warm
spells stretch these dates, but it may be that water temperatures are especially important
to this snake. Virtually no information on water snake activity in relation to water
temperature is available and this might be useful information for anyone to collect along
the Connecticut River.
It would be inappropriate not to mention the oft-observed behavior of a harassed water
snake. Commonly described as "aggressive," I contend that northern water snakes cannot
be considered any more aggressive than chipmunks or bluebirds. True, both of these
animals will defend themselves vigorously, biting and clawing, and sometimes doing
damage to the handler. When left alone, however, chipmunks and bluebirds pose little
threat to our persons. Northern water snakes bite people just as often as chipmunks and
bluebirds which is to say just about every time they are grabbed. With a large head,
fairly massive jaw musculature, and a mouth filled with six rows of sharp, recurved teeth,
water snakes can deliver an impressive defensive strike but only to those who lay
hands upon them. And this isn't even true all of the time. I've been able slowly
to approach some northern water snakes, carefully reach my open hands beneath their
bodies, and lift them into the air, all without the snake becoming agitated or me becoming
the recipient of a surprisingly strong bite. Sometimes, however, this doesn't work!
Rather, enjoy water snakes from a short distance, watching how they go about their daily
Throughout the entire Connecticut River watershed, the northern water snake is the most
common large snake to be found. The maximum total length is just under four feet,
though many outdoors-people claim (as they do with fish) that they've seen plenty
bigger. Water snakes have massive bodies, much thicker than most snakes, and when
disturbed can take in air, inflate their one, long lung, and appear even thicker than
normal. The large, ridged scales enhance their mien. Most of the northern water snakes
along the river are between one and a half to two and a half feet in length. Females grow
larger than males, often dwarfing them during the breeding season, which is typically in
May. At this time males may spend a lot of time swimming parallel to the shoreline
trying to scent receptive females. Occasionally water snakes, finding themselves caught
in the current, may try to take refuge at any convenient dry place - a floating log, a bridge
abutment, an arching tree trunk or a boat anchored to the bottom. To some people, the
vision of a large, dark snake heading straight for them is a bit disconcerting, to say the
least. For the rest of us, it is a lucky opportunity to observe one of the river's more
Water snakes are closely related to the most abundant and commonly seen snake in the
Connecticut River watershed the eastern garter snake (Thamnophis sirtalis). As such
they give birth to live young, typically in late August or early September. As many as
fifty or more may be born to the largest females, but normally 10 to fifteen 6- to 8-inch
babies emerge from the female inside small, clear membranes. Within an hour or so after
birth, the young break free and may be off on their own. However, evidence from other
snakes shows that there may be some interactions between mother and young, helping
them, in particular, navigate to winter dens or to shelter. This is unstudied in this common
animal and it would be fascinating to know of any observations where babies are seen in
close associations with their mothers.
It is somewhat of a question where northern water snakes spend the winter. Some years
ago, graduate students from the Wildlife Department here at the University told me that
while trying to make a cross-section out of an abandoned beaver lodge one late autumn,
they uncovered several adult water snakes that were deep inside the structure. Certainly
I've seen these snakes basking in early spring and late summer on lodges, so it does make
some sense they would be somewhat commensal with the mammals. There are reports of
water snake overwintering inside wells where they spend the majority of the cold weather
submerged, or mostly so. If this is true then it is possible that water snake might be able
to winter inside bank dens made by beavers, muskrats, otters, or even crayfish. Virtually
nothing is known of their winter behavior and it would be intriguing to understand just
what it is they are doing.
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