Serpents of Penn Dixie

Text and photos by Amanda K. Martin, M.S. Biological Sciences

Imagine trying to fit a whole watermelon into your mouth without chewing it or cutting it into smaller pieces. Sounds impossible, right? Well snakes have to do something similar to this each time they eat their prey, however they have adapted their skull structure in order to accomplish such an impossible feat.

Figure 1.JPG
Model skull of a snake (jaws closed).

Unlike a human jawbone (mandible), a snake’s jawbone is connected together with elastic ligaments that allow for stretching, however, the jawbones never detach! The two bones are moving independently.

Figure 2.JPG
Model skull of a snake (jaws opened).

That means the bones can move apart as a snake eats a large prey item. As the jaws unhinge, the curved teeth hook the prey item and they wiggle it down their body.

Figure 3.JPG
Model skull of a snake (jaws fully opened).

Even though snakes have amazing adaptations, such as their feeding method and ability to travel without legs, many people are afraid of them. These creatures like other wildlife are harmless to humans unless provoked. Even if they are provoked, they try to escape first and bites occur from people harassing the snake.

Figure 4.JPG
Dekay’s brown snake in a defensive position.

Snakes are incredibly important organisms in the ecosystem, acting as both predators (rodents, invertebrates, birds) and prey (hawks, turtles, large mammals). Snakes are ectotherms; they behaviorally regulate their body temperature by moving in and out of areas with heat. This ties them closely to their environment and they can be used to monitor ecosystem health. If local snake populations begin to decline, then their habitat may be degrading, which affects humans as well.

Figure 5.JPG
Forest habitat around Penn Dixie nature trail.

In the state of New York, there are 17 snake species, of which three are venomous. At Penn Dixie, we have four snake species: Northern water snake (Nerodia sipedon), Eastern garter snake (Thamnophis sirtalis), Eastern milk snake (Lampropeltis triangulum), and Dekay’s brown snake (Storeria dekayi).

Northern Water Snake

Figure 6.JPG
Water snake.

This is a large-bodied snake that primarily lives in the water. It ranges from 24 to 55 inches in size. They may be brown, tan or grayish in coloration with a white belly and have square blotches on their back. They spend most of their time in lakes, ponds, marshes, rivers, and streams, but will bask on river banks or on overhanging branches. They are carnivorous and eat amphibians, fish, crayfish, large insects, other reptiles, birds and small mammals. They do not constrict their prey, but consume them alive.

Water snakes have to avoid getting eaten themselves by other large snakes, raccoons, skunks, and foxes. They escape predation by swimming across a body of water or diving underneath the surface and anchoring their bodies to vegetation or logs. They typically remain submerged for five minutes, but can stay below for an hour and a half. They are quite beneficial to humans because they will eat diseased or dying fish and help control overpopulated areas. Many water snakes are often misidentified as venomous cottonmouths or water moccasins (Agkistrodon piscivorous), and are killed, but cottonmouths have bands instead of blotches and have a northern limit of southern Virginia.

Garter Snake

Figure 7.JPG
Eastern garter snake.

This is a common medium-sized snake that can be found throughout the United States. It ranges from 18 to 26 inches in size. They have three yellow longitudinal stripes running down their dark body; two on the sides and one down the middle. However, some have checkered patterns in between the stripes.  They have a white or light yellow belly. They live in a variety of habitats such as meadows, marshes, woodlands, and hillsides. They can commonly be found in moist, grassy areas and enjoy basking on or under rocks or debris. If you are ever in an area with a lot of small rocks, please do not step on the rocks, which could crush a hidden snake. They eat a variety of invertebrates (earthworms, crayfish, leeches, snails, slugs, insects), fish, baby birds, small mammals, amphibians, and other snakes. They appear to be immune to toxins released by toads and the consumption of this toxin may make their saliva slightly toxic which helps subdue prey. They immobilize their prey by biting down with their sharp teeth and swallow it whole.

Garter snakes are preyed upon by hawks and herons, large fish, bullfrogs, other reptiles, raccoons, foxes, squirrels, and shrews. They primarily avoid predators with their camouflage or they will flee into the water to avoid terrestrial predators. If you have ever tried to pick one up, they have a defensive mechanism where they release a foul odor called musk which usually deters the predator or you from handling them further. Like the Northern water snake, garter snakes are important low-level predators which act as both predator and prey within the ecosystem. They also are one of the few animals that can eat amphibians with toxic defensive mechanisms like toads and newts. Garter snakes also have a look-alike, the ribbon snake (Thamnophis sauritus). Ribbon snakes tend to be more slender, have a longer tail, and do not have a scale between the eye and nose, which is white in appearance, however they have not been found at Penn Dixie.

Eastern Milk Snake

Eastern milk snake by Stan Martin.

Like many snakes, this species has a slender, smooth scaled body with reddish or brown blotches on top of their gray or tan scales. The belly tends to have a black checkerboard pattern and adults can grow 19 to 40 inches in length. A Y- or V- shaped mark can be found on their neck, just under their head. They can be found in the woods, fields, marshes, farmlands, and suburbs. Many can be found living under logs, rocks, or old boards. They will eat small mammals, small birds, and smaller snakes. They constrict their prey by squeezing tightly until the animal suffocates and then proceed to eat their prey whole. Milk snakes have to avoid larger mammals such as raccoons, coyotes, foxes, and skunks. They will try to flee first, but they will sometimes vibrate their tail against the ground which mimics the sound of a rattlesnake.

Milk snakes get their name from a myth that they drink milk from nearby cows. Farmers kept finding this snake near their barns and fields, which they mistakenly thought the snakes were there for the cows instead of the rodents living in the barns. Milk snakes are actually quite beneficial especially to farmers because they eat pest species such as rodents. Although this is a common species, problems such as habitat loss and fragmentation, persecution (often mistaken for venomous snakes), predation by invasive species, and road mortality may lead to the disappearance of this beautiful species.

Dekay’s brown snake

Figure 9
Dekay’s brown snake.

This is a highly secretive, but a small dark brown or tan colored snake. There are two rows of dark spots running down its back, with a mid-back light colored band. The belly has a gray to pinkish coloration and sometimes has small black spots. In length, they usually range from nine to 15 inches. This is one of the few species that survives well in disturbed habitats such as urban areas. They prefer to stay under covered areas such as rocks or boards. Sometimes they will venture out during the day, but they will come out during the night when the weather is really warm. They will explore the area looking for prey such as insects, slugs, earthworms, and small tree frogs. They can also eat snails with their specialized teeth and jaws which helps them to pull the snails out of their shells.

When threatened, they will flatten their body to appear larger and may even release a foul smell called musk. Some predators are large frogs and toads, larger snakes, crows, hawks, blue jays, and weasels. These snakes are perfect friends for your garden since they prefer to eat a pest species such as snails. They control slug and earthworm populations, while serving as a valuable food source for their predators. During the winter, brown snakes will go into brumation (similar to hibernation in mammals) with other snakes in holes in the ground, old walls, and cracked foundations.

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s