Sunday, November 17, 2013

Diamondback Watersnake

Diamondback Watersnakes (Nerodia rhombifer) are a large thick-bodied, defensive, often ill-tempered snake. They are common in NW Missouri and are found living in aquatic habitats right alongside Northern watersnakes (Nerodia sipedon). They get their common name from the diamond-like pattern that runs the entire length of the body. They range in color from light brown, gray or olive-yellow. There will be 30 to 65 black markings covering their body and the belly will be either yellow or cream color. They reach lengths up to 63 inches but average length is typically 36 to 43 inches. In Northwest Missouri this snake is common to abundant in areas where they occur such as Squaw Creek National Wildlife Refuge. I make frequent trips to this refuge and almost always see this species upon each visit. Late in the season, around August and September it is common to find the juveniles basking along the ten mile auto tour route.

(Juvenile Diamondback Watersnake)

Mating takes place in the spring, usually in April or May. Females will bask on logs and along the shore of waterways warming the young she carries inside. This species gives birth to live babies sometime in August or September. Average litter size will be approximately 36 neonates. Not all offspring will survive to adulthood. Most in fact will be picked off by predators which range from owls, hawks, herons, foxes, raccoons, cats, large bullfrogs, fish, turtles. 

Diamondback watersnakes eat mostly aquatic prey which includes fish, frogs, tadpoles, and possibly small turtles. Game species are not generally on the menu as they are too fast for the snake to capture, instead they feed on rough fish. However they will consume game fish if found injured or deceased. Carrion seems to make up a significant portion of their diet.This species is especially adept at eating bullhead and other catfish. Even with the spines that these fish possess it does not seem to deter the snake in the least. I have witnessed these snakes with catfish whiskers protruding from their throat. They seem able to recover from what would appear to be a life threatening situation without any ill affects at all. Special lateral areas located along the trunk or upper portion of the body are super sensitive to touch, much like the lateral-line system a shark uses. The slightest touch against these lateral areas will cause the snake to lash out in a rapid sideways motion in a strike response to possible prey. This creates an increase in their ability to capture prey as they cruise along shorelines. Often frogs will hop erratically when disturbed and instead of jumping out of dangers way will run headlong into the very thing it is trying to get away from. These snakes rarely miss a meal when it hops so willingly into their midst. 

(Diamondback watersnake trying to remain hidden from predators while scoping the area for possible food)

These snakes are often confused with Cottonmouths and needlessly killed. As far as I am concerned anytime humans are killing snakes it is a senseless and needless act. It is especially so for watersnakes. They do share the same watery environs as cottonmouths (A.K.A. water moccasins)  which contributes in part to the confusion. Watersnakes by nature are quick to defend themselves from possible threats. They will flatten their heads and bodies and are prone to strike. If handled they will spray copious amounts of musk mixed with fecal matter. This often "aggressive" behavior causes people to think that they are faced with a venomous snake. For some reason, and I can't figure out why, people associate aggression or defensive behavior in snakes with venom. 

In reality all too often venomous snakes are calm and well mannered whereas harmless watersnakes can give even the most experienced snake handler a run for their money. Another feature of watersnakes is a diamond or triangular shaped head. This is also associated with venomous snakes. While it is true that many venomous snakes possess heads that are diamond-shaped, so do many non-venomous snakes. This is not an accurate way to identify a venomous species. I've seen black rat snakes, under the right circumstances appear to have diamond-shaped heads. 

(Diamondback watersnake showing a very definite diamond or triangular shaped head)

These snakes will often pester fisherman by chasing their catch while it is still attached to the fishing pole. They will try to eat fish on stringers and many times I've heard reports of these snakes coming completely out of the water attached to the fish at the end of a pole. This can be a bit unsettling if you are the fisherman, especially if you have a distinct fear or dislike of snakes. This fear can be amplified if you mistakenly believe that you are being faced with a cottonmouth. Try to remain calm and cut your line releasing both the fish and the snake. Please try to refrain from killing the snake. Remember the snake is only trying to survive and your fish on the line appears to be struggling prey and is easy pickings for a hungry snake. Keep in mind snakes that exhibit this type of behavior are watersnakes NOT cottonmouths. I've never heard of cottonmouths behaving in this manner. Watersnakes deserve a chance to live as an important component in the ecosystems where they occur. They are vital to the food chain both as prey and predator. They keep aquatic habitats healthier by eating weakened fish and carrion. They control bullfrog populations which can over populate areas where they exist. This creates a whole separate ecological problem, especially if you are red-legged frogs out west.

These snakes often travel over land to find suitable habitats. When current conditions are no longer favorable or food sources run low they will move to other areas, often great distances to find suitable resources. They are commonly found in wetlands, marshes, temporary watering holes, ponds, lakes and small rivers. If the areas they are in dry up they will move to temporary wetlands, then when the rains begin again and their home range becomes habitable again they will return. During rainy seasons they will often hunt in wet grasslands. These snakes will travel to hibernation sites that may be shared by other species. They will also use crawfish burrows to hibernate in. During one of my trips to Squaw Creek I visited one of their wet prairies to look for Massasauga Rattlesnakes. I did not find any rattlesnakes but I did find a large diamondback watersnake basking near a crawfish burrow. I cautiously approached and the snake did not move. As I got closer I was surprised that this snake did not lunge at me or act ornery in any way. Then it became apparent why. This particular snake was dead. It did not have any visible wounds, burns or other apparent reason for its demise. 

 The image at left is the snake in question. I spoke to the wildlife biologist from the refuge and he felt that the snake probably died from exposure due to the recent burn they had done on the prairie. Maybe a type of smoke inhalation. Either that or it could have died from exposure to the cold night time temperatures. Often snakes begin coming out of hibernation in March and will stay near their hibernation sites. If they happen to wander too far out and cannot get back to shelter before freezing temperatures return they may perish.All of us living in the Midwest know how rapidly weather conditions can change here. In the spring we can go from 65 degrees to 35 degrees within a single day. Whatever caused this, it didn't fare well for the snake. Other potential issues are things like fungal infections or diseases. There is a fungus that is attacking snakes all across North America. It was first noticed in rattlesnakes, but has since been found in other species including watersnakes. Often these snakes exhibit white, powdery-like substances on their scales or will show signs of having eye problems. Still other times they show no outward signs of fungus at all. I found a diamondback watersnake on the road at the refuge that had a definite eye issue. I didn't immediately think of it as a fungal infection. I thought it was a series of bad sheds. Often snakes have trouble shedding and an accumulation of shed skins may be found on one or more eye. I photographed the snake and then later wondered if it could be a fungal issue. I submitted the photo to several experts and none could agree. Some said definite fungal infections and others said that it was a bad eye shed. So I have no definitive answer, but will post the image for your consideration.

While these snakes are prone to bite, the wounds are generally superficial. Although because of a special enzyme they possess in their saliva the bite may bleed profusely. Simply wash the wound and cover it with a bandage and you should have no ill affects. Unwashed wounds however can cause infections; keep in mind what snakes are eating. Dead animals, fish and other aquatic animals. 

One of my favorite things to do is to take children out and explore. We often find snakes and I encourage kids to watch and even sometimes catch snakes to get a closer look. We always return them where we find them, unless of course we find them on the road then we place them somewhere safe away from road traffic. Allowing children to explore in a safe manner and be allowed to touch and admire these creatures creates a life long love of nature. Remember these children are the future voice of the natural world.

 Instead of killing or maiming something we do not understand, lets refrain from what might be our natural response to the unknown and marvel at the diversity of the natural World and try to appreciate all the creatures that call it home.