Snakes

Snakes

Figure 1. Dark phase timber rattlesnake (Crotalus horridus). Photo by William Hoffman, NYS DEC.

Objectives

  1. Describe the key characteristics used to identify snakes.
  2. Explain key elements about the biology of snakes that are important for their control.
  3. Communicate to clients why snakes cannot be killed.
  4. Describe the steps involved in properly treating bites from snakes. 

Legal Status in New York

Protected. NWCOs may not take, euthanize, possess, trap, remove, or transport any snake without a permit from the DEC.

Overview of Damage Prevention and Control Methods

Habitat Modification

  • Reduce sources of food including populations of rodents, fish, and invertebrates
  • Keep lawns closely mowed
  • Remove bushes, shrubs, rocks, boards, firewood, and debris lying close to the ground
  • Alter sites that provide habitat and protected basking locations
  • Remove shrubs and weeds from around building foundations

Exclusion

  • Seal all openings ¼ inch and larger with mortar, 1/8-inch hardware cloth, sheet metal, Copper Stuff-Fit or Xcluder™
  • Snake-proof fence

Frightening

  • Not applicable

Repellents and Toxicants

In New York, any use of toxicants or repellents by NWCOs requires the NWCO to have a pesticide applicator license.

Shooting

It is illegal to shoot any native snakes in NY

Trapping

It is illegal to trap any native snakes in NY

Species Profile

Identification

There are 17 species of snakes in NY. New York has 3 species of venomous snakes: timber rattlesnake (Crotalus horridus, Figure 1), northern copperhead (Agkistrodon contortix mokasen, Figure 2), and eastern massasauga, (Sistrurus catenatus, Figure 3). All are pit vipers. All native snakes are very beneficial members of the biota.

Figure 2. Northern Copperhead. Photo by William Hoffman, NYS DEC
Figure 3. Eastern massasauga. Photo by William Hoffman, NYS DEC

Definitions

People commonly call dangerous snakes, such as rattlesnakes, “poisonous.” The correct term is “venomous.” Venom is a toxic substance that is injected into a victim. It primarily is used to secure prey. Poison refers to a toxic substance that is ingested (swallowed) by a victim and usually is used as a defensive tool. Plants have poison, but spiders and snakes use venom that is injected through a bite with toxins and enzymes.

Physical Description

Snakes are specialized animals with elongated bodies and no legs. They have no ears or eyelids, but transparent scales cover the eyes. Organs of snakes are elongated. Snakes have a long, forked tongue, which aids the sense of smell. Particles from odors are picked up by the tongue and inserted into a 2-holed vomeronasal organ in the roof of the mouth.

The 2 halves of the lower jaw are not fused, but are connected by a ligament. The configuration of the jaw allows snakes to swallow food much larger than their heads. Snakes are ectothermic (cold-blooded) and may consume only 1 meal in several weeks. Snakes may hibernate during cold weather or aestivate during hot summer months. Snakes consume little or no food during times of decreased activity.

Snakes vary in length, depending on age and species. Scientists typically measure a snake from the tip of the snout to the vent (cloaca opening), as tails may be damaged. Color usually is not a primary indicator for the identification of snakes. Coloration can vary greatly by area, genetic variation, and age of the snake.

Use these features to identify snakes.

  1. The keel is a ridge that runs along the middle of the scales in some types of snakes. Like the keel of a boat, the ridge may be pronounced, less pronounced, or absent. Rub a finger across the width of the skin of the snake to feel for the presence of a keel.
  2. Inspect the vent. Check if the scale that covers the vent is divided or single.
  3. Unlike color, patterning can be helpful for identifying snakes, although in some species the pattern of juveniles differs considerably from adults. Identify whether the snake has stripes, blotches, or solid coloration.
  4. Snout to vent length may be helpful but can be misleading in small snakes.
  5. Number of scales across the width of the snake
  6. Check if the head scales are large or small.

Venomous versus Non-Venomous Snakes

Several characteristics can be used to distinguish between venomous and non-venomous snakes. Venomous snakes in NY are all pit vipers and have a heat sensing pit (loreal pit) on each side of the head, midway between the eye and the nostril. Non-venomous snakes do not have pits.

The pupil of non-venomous snakes is perfectly round (Figure 4). The pupil of venomous snakes is vertically egg-shaped, like cat eyes or like a football on its end. In very bright light, the pupil may be a vertical line due to extreme contraction to shut out light.

Figure 4. Non-venomous snakes have a round pupil and no pit between the eye and the nostril. Image by PCWD.

Rattlesnakes have a rattle on their tail; a segmented string of keratin that adds a segment to the rattle each time the snake sheds. The sound is unmistakable and can be heard from as far as 50 yards away. Timber rattlesnakes typically have two color phases, light and dark, and can vary from an almost complete black to yellow. Eastern massasaugas are small grayish black snakes with saddle or diamond-like patches along their backs. They also have a rattle, but is reduced in size, and sounds like an insect buzzing. Copperheads have triangular, coppery-red heads and their upper body is pinkish tan to dark brown with hourglass-shaped cross bands.

All snakes have teeth for gripping prey but only venomous snakes have fangs for venom delivery.

Voice and Sounds

Some snakes, such as hognose snakes, may puff up and hiss in such a manner that sounds like a rattlesnake. Many snakes shake their tails, which can sound like a rattle, especially when they are in dry leaves or weeds.

Tracks and Signs

Snakes rarely leave signs of their presence. It takes a careful eye to notice disturbances in soil that indicates the movement of snakes. Skins of snakes are sometimes found in attics and crawl spaces. Look for paths in dust, drags through spider webs, and skins that have been shed. Note that skins shed by snakes tend to be 20% longer, on average, than the total length of the snake that shed it.

General Biology

Reproduction

Snakes’ mating period varies by species from early spring to late summer. Female snakes may lay eggs or give birth to live young depending on the species. Eggs hatch and young are born in late June through September. Juveniles of species that are venomous are just as venomous as adults.

Denning Cover

Snakes seek locations for protection and thermoregulation. For example, a rock exposed to the sun provides warmth and a rock wall provides protection and cool temperatures. All snakes hibernate during the winter in underground dens, or hibernacula, that protect snakes from freezing temperatures. Hibernacula form around structures including sump pumps, rock walls, basements, crawl spaces, and other locations that are safe from winter freezing. A single hibernaculum may contain multiple species and hundreds of snakes. If the temperature of the space they occupy is warm enough, such as the walls of a heated basement, active snakes may be found in the house even during their inactive season.

Behavior

The behavior of snakes is determined more by temperature than by season. Snakes become lethargic at temperatures below 50°F. In most cases, snakes will move away when approached. Snakes do not charge or attack people, with the exception of racers that usually enter a state of panic and engage in a behavior called “periscoping,” in which they lift their head above the grass to look for danger and then duck down. On rare occasions, racers will bluff by advancing toward an intruder, although they retreat rapidly if challenged. When cornered, snakes react with a variety of defensive tactics that vary by species. Defensive tactics include playing dead by exposing the belly, hissing, opening the mouth in a menacing manner, coiling, emitting an odorous fluid from the vent, striking, and biting.

Habitat

Not all species of snake require the same habitat. Some live underground, some live in trees and shrubs, and some live on and around water. Snakes such as racers and rattlesnakes inhabit rock ledges, other species such as smooth green snakes prefer shrubby edges, while almost all species can be found in and around rock walls, stacked lumber, junk piles, and other soft edges such open wetlands and gardens. Venomous snakes live in many different environments, from coastal plains to forests to mountains. They are most common in rough terrain and wherever rodents are abundant. Timber rattlesnakes have scattered populations across New York, mostly along the Hudson River Valley, with some populations occurring in the western and northern parts of the state. However, they are relatively rare in New York. Copperheads also have scattered populations in New York, and are restricted to the Hudson River Valley. They are most common in open areas with many rocks. Eastern massasaugas occur in very few isolated localities in the state, and rely on wetland and open field mosaics for optimal habitat.

Food Habits

All snakes are predators, and different species eat a variety of sizes and kinds of animals. Milk snakes and rat snakes primarily eat rats, mice, and chipmunks, eggs of birds, and baby birds. Some snakes, such as green snakes, primarily eat insects. Some small snakes, such as worm snakes, eat earthworms, slugs, and salamanders. Water snakes primarily eat fish, frogs, and tadpoles.

Damage Identification

Property owners typically discover the presence of snakes by direct observation or discovery of a skin. On average, a skin of a snake is 20% longer than the snake that shed it.

Damage to Structures

Snakes do not damage structures.

Damage to Livestock and Pets

Some snakes eat eggs and young birds. A classic sign of the presence of snakes is the daily disappearance of eggs. Most mammals break several eggs and leave the shells behind. Snakes swallow them whole and usually eat just 1 per day. Pets and livestock may be severely injured if bitten by a venomous snake, especially if the bite occurs on the nose or face, and will require veterinary care.

Damage to Landscapes

Snakes do not harm landscapes or gardens. They help reduce populations of insects and rodents and usually are considered beneficial.

Health and Safety Concerns

Snakes that are native to New York do not hunt or attack people, although a provoked or harassed snake will defend itself. When a person is bitten, it usually is due to the snake reacting defensively after being handled, threatened, or approached.

Never put your hands or feet into holes or other areas that you have not inspected visually. Wear leather gloves and use a snake tong or hook when capturing and handling snakes. When walking or inspecting areas where an encounter with a venomous snake is likely, wear protective leggings and always step on logs, as opposed to stepping over them without looking.

Exotic snakes present special safety issues. Exotic snakes are non-native snakes that once were pets but were released into the wild. Some exotics are extremely dangerous due to their large size and toxic venom. While few complaints regarding dangerous exotic snakes have occurred, the risk is increasing as they become more popular in the pet trade. We strongly encourage NWCOs to learn about exotic snakes, particularly those commonly kept as pets or in private collections. A NWCO in NY is only licensed to handle wildlife. Exotic, non-native snakes are not considered wildlife. So, a NWCO cannot capture, handle or transport exotic snakes as a NWCO. However, NY does allow a person to transport an exotic snake to someone who is legally authorized to possess the snake, such as a veterinarian or a zoo.

Snakes have few diseases that are transmissible to humans. Salmonella is rare in wild snakes (versus snakes from the pet trade), with the notable exception of water snakes that inhabit waters with abundant waterfowl. Some snakes carry ectoparasites, but most are harmless to humans. Maintain standard sanitation procedures to protect yourself from snake-borne diseases.

A bite from a non-venomous snake has no venom and will not harm the long-term health of the victim. Some individuals have been bitten several thousand times by non-venomous snakes and suffered no adverse reaction. They only required basic first aid for any of the bites. Non-venomous snakes cause harm by frightening people who are unfamiliar with them and by possible infection from a bite, just as with any break in the skin. A bite from a non-venomous snake should be treated as any other minor flesh wound. Clean the area and treat it with an antiseptic.

A bite from a venomous snake usually results in an almost immediate bodily reaction and requires immediate medical attention. Swelling, tissue turning a dark blue-black, a tingling sensation, and nausea are common reactions to venom of snakes. If no signs are observed or felt, the bite was likely from a non-venomous snake or the bite did not contain venom (it was dry). Over ½ of the bites from rattlesnakes lack venom. Snakes dispense venom to capture and digest prey; they have little interest in people.

First Aid for a Venomous Snake Bite

First, move away from the snake to avoid any further bites. Keep others in your party away from the snake. Try not to panic; stay as calm as you can. Panic will increase blood flow and the speed that venom travels through the bloodstream. Do not drink alcohol after being bitten. Alcohol dilates veins and will aid in the spread of the venom.

Seek medical care immediately. Call 911 and transport the victim to the closest hospital. If skilled at handling snakes and the proper equipment is available (snake hook or tongs and a sealable container) capture the snake and bring it in for identification. A photograph of the snake can suffice but stay at least 2 snake-lengths away.

Remove constrictive clothing and jewelry. Swelling will prevent such articles from being removed and can result in a tourniquet action. Do not use a tourniquet or ice, as they can increase tissue damage. Do not cut the skin or apply suction to the site of the bite. Clean the wound with water to remove residual venom on the skin and reduce the risk of infection.

Damage Prevention and
Control Methods

All snakes are protected by law in New York state under Environmental Conservation Law 11-0103(2)(c) and the (6) New York Codes, Rules and Regulations Section 3.3 in that there is no open season or lawful take of any snake at any time. Nuisance Wildlife Control Operators are provided the opportunity to conduct management of nuisance wildlife in New York State under ECL 11-0507, 11-0521 and 11-0523. Snakes are not included under these statues, and removal or management of any snake is further restricted.

Such activity requires an additional license from the Department of Environmental Conservation. That limits control options to non-lethal methods such as habitat management and exclusion. Time spent educating people about snakes is valuable and important.

Habitat Modification

The primary food for most snakes, especially larger ones, includes birds and their eggs, and rodents such as rats, mice, and chipmunks. No program for control of rodent-eating snakes is complete unless it includes removing rodents and habitat for rodents. Put all possible sources of food for rodents in secure containers. Clean up food for pets after each feeding and store the food where it will be unavailable to rodents. Clean up spilled seed under bird feeders. Keep all vegetation closely mowed around buildings. Remove bushes, shrubs, rock piles, boards, wood piles, and debris lying close to the ground, as these provide cover for rodents and snakes. Alter landscape to reduce areas for basking. If you eliminate the rodents, snakes will move elsewhere.

Exclusion

Snakes enter houses, barns, and other buildings when conditions are suitable inside the buildings and means of entry are available. Snakes particularly are attracted to rodents and insects, and cool, damp, dark areas associated with out-buildings and basements. All openings ⅛-inch and larger should be sealed to exclude snakes. Because snakes do not gnaw or damage structures to gain entry, sealants and closures suitable to exclude mice will protect against snake entry. Secure openings as you would to exclude mice.

Check the corners of doors and windows, around water pipes, and entrances for utility lines. Holes in masonry foundations (poured concrete and concrete blocks, stones, or bricks) should be sealed to exclude snakes. Holes in wooden buildings can be sealed with sheet metal, Copper Stuf-Fit, Xcluder™, or ⅛-inch mesh hardware cloth. Weep vents can be secured with Xcluder™ cloth or weep vent screens. Consult the module on exclusion for additional information.

In some cases, homeowners may obtain peace of mind by constructing a snake-proof fence around their home, yard, or livestock pen (Figure 5). A properly constructed, snake-proof fence will keep out all venomous snakes and most non-venomous snakes (some non-venomous snakes are good climbers). The cost of fencing a whole yard may be high, but it costs little to enclose a chicken coop or a play area for children who are too young to recognize snakes that are dangerous.

Figure 5. A properly constructed snake-proof fence prevents entry by most snakes. Image by PCWD.

A snake-proof fence should be made of heavy galvanized ¼-inch mesh hardware cloth that is 36 inches tall. Bury the lower edge 4 to 6 inches in the ground. Slant the fence outward from the bottom to the top at a 30o angle (Figure 6).

Figure 6. Side view of a drift fence to exclude snakes.

Figure 6. Side view of a drift fence to exclude snakes.

Place stakes for support inside the fence and make sure that gates are tightly fitted. Gates should swing inward because of the outward slope of the fence. A 36-inch, vertical fence with a 12-inch lip at the top, facing outside, and angled downward at a 30o angle also may work.

Holes under the fence should be firmly filled, with concrete if possible. Mow the vegetation just outside the fence, as snakes might use plants to climb over the fence. If necessary, support the fence with more and sturdier stakes and strong wire connected to the upper edge.

A boundary made of lava rocks may be as effective as a fence. The course texture of lava rock appears to divert many rodents and snakes, including pit vipers. Border an area with lava rock that is at least 12 inches in width to deter snakes from entering. Depending on the region, the width of the boundary can vary (i.e., large snake species may be able to find a way across). Boundaries of lava rock work well to exclude species that are climbing or arboreal. Lava rock is a common landscaping item and can help exclude snakes while maintaining an attractive yard.

Frightening Devices

Frightening devices are not applicable for the control of snakes.

Repellents and Toxicants

In New York, any use of toxicants or repellents by NWCOs requires the NWCO to have a pesticide applicator license.

Before using any product, you must check the New York State Pesticide Administrator Database (NYSPAD) to see if the product is registered for use in NY and for the target species. For example, if the product is registered for use on squirrels, it cannot be used for deer. The following are presented as examples of repellents and toxicants that may be effective.

Repellents

Several repellents for the control of snakes are on the market. Research on the applications’ effectiveness is either lacking or inconsistent. Liquid Fence Snake Repellent uses a 2- to 3-foot wide band of mint oil, sodium lauryl sulfate, thyme oil white, putrescent egg solids and garlic oil to protect a perimeter. Currently, the active ingredients in Dr. T’s Snake-A-Way Active include sulfur and naphthalene. Use a band application around the area to be protected.

Toxicants

No toxicants are registered for use on snakes. It is illegal to kill native snakes in NY.

Shooting

It is illegal to shoot a snake in NY.

Trapping

It is illegal to trap a snake in NY.

Disposition

It is illegal to capture, release, move, or kill any native snakes in NY.

Acknowledgments

Author

This material was adapted and updated from a chapter by James L. Byford in Prevention and Control of Wildlife Damage, 1994, published by the University of Nebraska–Lincoln Extension.

Reviewers

Dennis Ferraro, University of Nebraska-Lincoln; Tim L. Hiller, Oregon Department of Fish and Wildlife; and Rebecca Christoffel, Iowa State University reviewed the original document.