There are hundreds of species of snakes in the U.S. and many of them can end up in our gardens. With few exceptions that I can think of, the presence of a snake in the garden is always good for the garden... though obviously the poisonous varieties are not always good for the pets, children and gardeners. Fortunately poisonous snakes rarely end up in most gardens around the country. However there are some regions where poisonous snakes are sometimes encountered in gardens. This article is mostly an introduction to the more common snakes encountered in U.S. gardens and how to tell the dangerous ones from the safe ones.
The Non-Poisonous Species:
Probably 90% of the snakes one finds in North American gardens are in the family Colubridae, of which the most common species are probably the Garter Snakes (Thamnophis spp.) or related species (e.g., Ribbon Snakes). These are often mistakenly called gardener snakes and I have to admit that is what I called them when I was young as they were the only snakes that I ever found in our garden. Garter snakes are small, thin snakes that tend to move fairly quickly and can give one a start when they are first encountered.... Though realistically I realize just about all snakes give the majority of gardeners a start. Garter snakes are one of the best snakes to have in the garden as they eat almost exclusively insects. Saying this, most gardens do not have enough garter snakes in them to make a huge dent in most garden's insect populations, so they are not usually considered the primary biological control for insect problems. Garter snakes come in a large variety of color patterns from checkered to striped and with oranges, reds, turquoise, browns, blacks, greys and yellows. These are among the most colorful and variable of American snakes. All American Colubrids are essentially non-poisonous by the way (some have an extremely mild toxin but none of those are likely or are able to bite humans).
Above are four different varieties of Garter Snakes one might encounter in the garden (photos Wikipedia)
Closely related to Garter Snakes are Water Snakes (Nerodia species) and these are also found frequently in gardens, particularly in the northeastern US. Unlike Garter Snakes, Water Snakes are relatively boring in color and appearance- brown with some darker colors mostly. And as the name suggests, they like living near water (not always in water, though). Do NOT confuse these smaller snakes with Water Moccasins (aka Cottonmouths) which are much larger blackish snakes from the US southeast that are pit vipers (related to Rattlesnakes) and quite poisonous. The two look very little alike.
US Water Snakes (photos Wikipedia)
In my area of the country (southwest) some of the more common species of snakes encountered are the constrictors. They are still in the same family as the Garter and Water snakes, but have the ability to constrict their prey (usually rodents), rather then just gobble them up as the smaller snakes do. These larger constrictors include the Gopher Snakes (Pituophis species) and King Snakes (Lampropeltis species). Pine Snakes are closely related to Gopher Snakes and are more common in the eastern half of the country. King Snakes are not uncommon in the east either.
The Gopher Snake and its relatives are fairly big snakes and can grow up to seven feet long, which could really startle a gardener when encountered in the garden. However, as with all other American Colubrids, are completely harmless. These snakes are particularly good for the garden in that they keep the rodent populations down. However, they are fairly shy species and active gardeners will usually scare these away. When surprised, these snakes often ‘rattle' their tail, and if in dry brush or leaf litter, the resulting sound can remind one of a rattlesnake. This behavior is presumably designed specifically to give a potential predator pause, perhaps long enough to give the snake a chance to get away.
Gopher Snake adult (left) and baby (right)
King Snakes are smaller than Gopher Snakes, but are still relatively large for North American snakes and are also among the most colorful and striking of all the American snakes. King Snakes have a more broad diet that includes lizards and other snakes sometimes. They are perhaps best known for their apparent immunity to rattlesnake venom and often prey on rattlesnakes with little affect to their own health. These are definitely great snakes to have around in a garden (though I am not particularly happy about their eating of lizards... oh well). These snakes are usually either black and white in striking patterns, or brightly colored with reds, blacks and yellows. The multicolored species sometimes scare gardeners as there is a very rare species of poisonous snake which looks very similar to these snakes, called the Coral Snake (discussed below). Below is a Youtube video showing how to tell Coral Snakes from our non-poisonous American snakes (as the video points out, this color scheme only works for US snakes... not Central or South American snakes!). I just remember that if you don't consider black a color, then all the snakes where the two colors (red and either off white or yellow) don't touch each other, the snake is not poisonous. Touching bands of colors is a bad thing.
All the colored King Snakes, Milk Snakes (see below) and particularly Coral snakes are actually relatively rare compared to the other above snakes and finding them in the garden is pretty unlikely anyway.
Common King Snake (left) and rare but popular color morphs of some king snakes (right) (left photo Wikipedia)
other more color types of king snakes (left photo Wikipedia)
The Rat Snakes (Elaphe species) are another common species encountered in some US gardens (and farms, mostly). These are also constrictors, but unlike the above constrictors, tend to be more fast-moving species and are on the ‘grumpy' side when it comes to being captured. They are Colubrids and completely non-toxic, but are one of the species more likely to bite you if you grab one, so best to leave these alone. However, they will not attack you or any pet as long as they don't get picked on, so they are still quite safe in the garden.
Two varieties of rat snakes (leflt photo Wikipedia)
Rat Snake photo from Wikipedia
The related species, Milk and Corn Snakes (also Elaphe sp.) are their friendly, slower cousins and are among the nicest, most ‘peaceful' of all the garden snakes. These snakes also are quite colorful and a few can have the Coral Snake color bands, but just remember if the yellow and red colors don't touch, it's a safe snake. Milk and Corn Snakes actually make excellent pets. And these eat primarily rodents (make excellent ‘barn' snakes). They are not quite as shy as Rat Snakes or Gopher or King Snakes so might actually hang around a garden for some time keeping the bad creatures away.
Milk Snake (left or upper) Corn Snake (right or lower) Both photos Wikipedia
Another somewhat common species of snake found on the Midwest and east coast are Hognosed snakes (Heterodon species). These are most famous for playing dead (rolling on their backs and sometimes even hanging their tongues out) when disturbed. These are rather peculiar looking snakes with upturned ‘noses' that eat almost exclusively frogs and toads. So they are not particularly good or bad for the garden, but are harmless nonetheless. There is some debate about whether these have some degree of toxicity but it does not appear to be enough to hurt a human... nor to these ever bite people anyway. They can startle, however, when not playing dead, by flattening their heads and hissing like some scary creature. But this only lasts until the disturber is obviously not fooled.
Hognosed Snake photos
The ‘fast' snakes, as I call them, are another moderately common group of North American Colubrids, but are really pretty rarely encountered in gardens. These are the Racers and Coachwhip snakes, another irascible group of snakes best left alone (though challenging to catch anyway). These are generally very long and skinny snakes and live on rodents and reptiles they chase down and squeeze.
Racer in a tree (left) and juvenile Coachwhip Snake (rigth). Both photos Wikipedia
Indigo Snakes are an east coast or Texas species and are among the largest of all North American snakes (Drymarchon species). These are also one of the best species to keep as pets (though they are protected and not really legally available as a pet species) as they are very docile slow snakes, and a beautiful shiny black color. They eat just about anything they can, including rattlesnakes. These would be an excellent garden species, but are frankly decreasing in numbers and become quite rare. They also tend to have very large hunting territories that far exceed the size of most people's gardens (often up to and over dozens of acres in size).
Indigo Snakes (left photo Wikipedia)
There are many more species of non-venomous snakes in North America, including a rosy boa and rubber boa, worm snakes, green snakes, ring-necked snakes and night snakes (these latter two nocturnal species are technically mildly venomous, but rarely can be provoked to bite humans), but really most of these are rather rare and less frequently encountered. All are very safe, relatively small and excellent garden species, though.
Rubber Boa (left) Rosy Boa (right) both photos Wikipedia
Rough Green Snake (left) and Ring-necked Snake (right). Both photo Wikipedia
Ribbon Snake (left) Night Snake (right) Both photos Wikipedia
The Poisonous Species:
With the exception of the Coral Snakes which are in the Elapid Family (same family Cobras and Kraits are in), all the poisonous snakes in North America are Pit Vipers. Of these, only two are not Rattlesnakes. That means that almost all the poisonous snakes in North America are Rattlesnakes, and Rattlesnakes are very different in appearance to all non-poisonous snakes (and not just in having rattles at the end of their tails). Thankfully, the other two pit vipers (Water Moccasins and Copperheads) are also relatively easy to tell apart, and basically have the same body structure as Rattlesnakes, only no rattles and a tad slimmer. So when one encounters a snake in their garden, if they do not have the following very distinctive features, they are safe, non-venomous snakes and are harmless.
Without exception, all Pit Vipers have thick, relatively short bodies, narrow neck with wide, triangular heads. No non-toxic snakes have this sort of body shape in the US. See the photos below showing the differences. All nontoxic snakes have heads barely bigger than their necks and few have thick short bodies. With few exceptions, poisonous snakes have elliptical pupils (at least in bright light) and non-poisonous snakes do not.
Typical Viper head above (left) with large, flattened head, skinny neck and eliptical pupils (hard to see in that photo); Right is Hognosed Snake with more typical non-poisonous snake profile.
Rattlesnakes (Crotalus species)- there are literally dozens of species of rattlesnake in the US and all are poisonous, though some are quite a bit more poisonous than others. Most Rattlesnakes are encountered in the southern states, particularly in the southwestern US. But some rattlesnakes can be found up north as well. In my neck of the woods, Rattlesnakes are pretty common, though in the middle of suburbia, they are never encountered in the garden. But in neighborhoods that border forests and deserts, Rattlesnakes are not that rare and can often end up in one's yard. All Rattlesnakes have rattles, though not all Rattlesnakes use them all the time. This is unfortunate and one can sometimes stumble upon one of these snakes or even step on one and get bit without any warning. Rattlesnakes do not have to coil up and strike to bite nor do they have to rattle first, either. On the other hand, no rattlesnake is ever going to pursue you or your pet (save for really dinky dogs and cats) in an aggressive manner. They only want to get away from people and larger pets (too large to eat). If one finds a rattlesnake in the garden, it is best to get the dogs and cats inside (children, too, of course) and call the Fish and Game department, or Animal Control in some areas of the country are equipped to help remove a rattlesnake from your yard. I do NOT recommend trying to get rid of it yourself and I am NOT a proponent of killing ANY snake. Though I can certainly understand why someone would go ahead and kill one. That just would not be my choice.
Typical Rattlesnake rattle... thank goodness most North American venomous snakes have one of these- helps in the identification process (as well as warning behavior) photo Wikipedia
Rattlesnakes come in many sizes and colors and can be among the most beautiful of all North American snakes if one just looks at their markings. Pigmy Rattlesnakes are southeast coast snakes that top out around twenty two inches long. They tend to be less dangerous than larger species as well. On the other hand, Eastern Diamond Back Rattlesnakes can grow up to eight feet in length, weigh over five pounds and are among the most dangerous of all American snakes (North and South America). When it comes to species danger, size does matter. However, baby diamondback rattlesnakes can sometimes deliver a larger amount of venom than an adult as the babies do not have the control some adult snakes have (some adult snakes will emit less venom in biting a large scary animal (like us) as they bite us in self defense and losing the venom really does them no good), so when it comes to size alone within a species, it may not matter that much. Some rattlesnakes have neurotoxins along with the ‘normal' pit viper toxins making them even deadlier. Still, most people and pets who get bitten by rattlesnakes survive the experience.
Pygmy Rattlesnake on left and at the other end of the spectrum, Eastern Diamondback Rattlesnake on rright (photos Wikipedia)
Rattlesnake found in the Western Us (left); right is Mojave Green Rattlesnake, one of the most toxic rattlesnakes there are Photos Wikipedia
Few more Rattlesnake photos from Wikipedia above
Several shots above of Rattlesnakes in captivity. Helps to show a variety so one might still be able to identify them in the back yard
The remaining two pit vipers found in the US are the Water Moccasins and the Copperheads (Agkistrodon species). The latter is a relatively small snake with a relatively weak venom and though getting bit by one is certainly no fun, very few serious bites occur. This snake is ‘copper colored' and quite attractive from a pattern and color point of view. It has the typical pit viper head and body, but no rattles on the tail. This is an eastern species and accounts for more pit viper bites than any other snake on the east coast.
Copperhead photo from Wikipedia
The Water Moccasin is the more feared species, however, because it is usually encountered while one is swimming, and most people feel more vulnerable in such a situation. It is the only poisonous snake one will encounter swimming in North America. All other snakes routinely found in water are non poisonous. That does not mean rattlesnakes and Copperheads will always drown if tossed into a pond, but they are very poor swimmers and would never purposefully enter the water. Cottonmouths (the other name for Water Moccasins) are best known for their dark bodies and white to pinkish-white mouths that they display readily when threatened. Sometimes, though on very rare circumstances, these snakes can act somewhat aggressively in water when they feel their territory is threatened, making them the only snakes in the US that might purposely approach a human or large pet. These snakes can sometimes exceed five feet in length and are the ‘slimmest' looking of the Pit Vipers sometimes making them a bit less obvious as poisonous snakes. However, their vertical pupils will quickly set them apart from most all the non-poisonous snakes one is likely to encounter in the US (a few relatively harmless night snakes have vertical pupils, but these do not bite humans nor are they hardly ever encountered as they tend to be only nocturnal). Water Moccasins only are found in the Southeastern US.
Water Moccasin (aka Cottonmouth) snakes from Wikipedia above
Last and probably least is the Coral Snake, an extremely poisonous species with a poison quite unlike that of the Pit Vipers. Antivenom is hard to find for this species, but fortunately bites from Coral Snakes are extremely rare, partly due to the snakes themselves being so rare, secretive and very non-aggressive and practically too small to effectively bite a person or a larger pet. Still, avoiding them is prudent should one happen upon one in their garden.
Coral Snake photo (left); compare to variety of Milk Snake (right). photos from Wikipedia
So now next time you happen upon a snake in the garden, you will be able to recognize that it is most likely a harmless and helpful garden friend, and not set out to kill or maim it needlessly. And I hope you will also be able to recognize and dangerous snake as well, and avoid it as best possible. And despite the title of the article, there really are no bad snakes... just snakes in bad places. And all snakes are beautiful in their own way.