Not the same as “Mammal.” Animals do include mammals, but also clams, insects, reptiles (including birds), jellies, barnacles, but not protozoans or bacteria. 

Batesian Mimicry—(see Mimicry, Batesian)

Berkshire Plateau

A physiographic upland, about 30 miles wide and 50 miles long, sometimes called the Berkshires or the Hilltowns. Driving west from the Connecticut River or east from the Housatonic Valley, on Routes 20, 9, 2, or I-90 you quickly climb to 1000 feet elevation (the highest point—1724 feet—on I-90 has a sign). Beyond this point, the terrain flattens out to the other end of the plateau. This region appears to be somewhat of a barrier preventing species from moving east or west between the Housatonic and the Connecticut valleys. The Plateau itself is a refuge for many northern New England species with its extensive wetlands, boreal forests, and abbreviated summer.

Birthing Rookeries

Locations where (usually) multiple gravid female snakes congregate for extended periods in the summer and often where they give birth to their live young by early autumn.


Also called a spectacle or eye-cap. This is the specialized scale that covers each eye. It is shed along with all other scales and is typically present if you find a complete snake skin.


Body temperatures of ectotherms can fluctuate dramatically even during the active season and, although the response to winter varies, all snakes avoid sub-zero conditions. Unlike truly hibernating mammals (woodchuck, jumping mice) the process of dropping their body temperature and respiration rate for the winter is not as great a physiological process for ectotherms. For example, they can come in and out of their torpor in winter, or during cold spells, relatively easily. It seems appropriate to not use the term "hibernation" for ectotherms; brumation fits the bill.


A term used variously in different contexts. In general it indicates a diet of entirely or predominately animal protein. Variations include diets consisting of insects (insectivore), or fish (piscivore). The mammal order Carnivora includes such diverse animals as skunks, bobcats, bears, and seals, only a few of which have truly carnivorous diets; however they all have the modified shearing/crushing teeth that suggest they are related and in the same clade.


An important term in evolutionary systematics (called Cladistics) defined as a lineage of organisms that include a common ancestor and all its descendants. The clade Reptilia appropriately includes birds (since bird ancestry is well imbedded in dinosaurs). We are part of the Mammalia clade. If you’re new to cladistics, take a peek here.  


Also called Vent. The dual-purpose opening for eliminating digestive wastes and for reproduction. In snakes, the cloaca is covered by an enlarged ventral scale called the anal plate.

Cold-blooded—(see Ectotherm)

Connecticut Valley

Typically refers to the watershed of the Connecticut River in Massachusetts, and in particular, the main stem. The upper and lower Connecticut Valley is divided by the Mt. Holyoke range. The Connecticut River divides the states of Massachusetts and Connecticut and is the boundary between Vermont and New Hampshire. 


Active at dawn and/or dusk. Many animals, from mosquitos and whitetail deer to Dekay’s snake, are especially noticeable at these times. It does not preclude activity at other times of the day. 


A morphology (structure), behavior, and often color and pattern of an animal that helps it blend with its surroundings. For example, Milksnakes are difficult to see on a sun-dappled forest floor covered with leaf litter. Opposite of aposematic—animals with brilliant, often contrasting color or patterns.


Active in the daytime. Racers and Gartersnakes are decidedly so. Some species, like Milksnakes, may be nocturnal in the summer, but diurnal in spring and fall. 


Commonly known as shedding, it is the process of replacing the outer layer of skin, often in a single piece. Each year, this may occur several times or just once.


Organisms that live on the outside of a snake’s body and gain some nourishment from the surface or pierce the skin to feed on blood or other tissue. Examples include ticks and leeches. The opposite is endoparasites, which live inside the body (e.g., liver flukes, tapeworms).


Animal species that use external heat sources to regulate their body temperature. Full basking in the sun, curling up beneath a warm rock, and exposing just a part of a coil from beneath the leaf litter, are among the behaviors that allow snakes to keep their body within a relatively narrow optimal temperature.  Ectotherms (most animals on earth, from insects to fish, are ectotherms) need less energy (food) to survive but require above-freezing temperatures. Ectothermic reptiles abound in deserts and the tropics but virtually disappear towards the arctic. Because snakes require much less food than mammals, some snakes can go for months without eating. I'm an endotherm and can go about an hour.


Most kids learn about endangered species when a teacher introduces whales, tigers, pandas, or sea turtles, all of which are globally endangered. These are endangered (in danger of becoming extinct) because they live in relatively small places on earth and in all those places their populations are dwindling and/or threats to their continued survival are imminent. 

Most countries maintain a list of the plant, animal, fungi, protozoan, and bacteria that are rare or endangered within the confines of their artificial political boundaries. So, Kenya lists cheetahs as endangered, as does Tanzania, Botswana, and Zambia. There is also a critically small population in Iran.

The United States list is maintained by the US Fish and Wildlife Service and includes about 600 animals, 1400 plants, and no fungi, bacteria, or protozoans. Within the artificial, political boundaries of the US these species are in danger of disappearing; however the same species may be common or rare in neighboring countries.

Each state also has its own separate endangered species listings. Most rare and endangered programs were jump-started with funding by the private Nature Conservancy. Each state, through its Fish and Game Agency, compiles a list of endangered species within the confines of its own, artificial political boundaries. In our state it’s the Massachusetts Natural Heritage and Endangered Species Program (MNHESP) that keeps records, makes management decisions, and helps formulate regulations to ensure these plants and animals don’t disappear (become extirpated) from our state.

Like most states, the MNHESP makes a distinction between species that are Endangered (about to become “extinct” in the state—a better term to use is extirpated), and those that are “Threatened.” Another category called “Species of Special Concern” indicates populations that exist in very limited numbers or are likely declining. Not all states use the same criteria for listing.


Organisms that maintain relatively constant body temperatures, despite wide temperature variations in the environment. Typically this is accomplished by an active metabolism that turns food into heat. Once thought to be unique to mammals and feathered reptiles (birds) it seems clear that some reptiles (leatherback sea turtles) and a few fish (tunas) may also be functionally endothermic.


Simply defined, it is “change through time” or more accurately "descent with modification" as clearly shown by the fossil record. Evolution is one of the great lightning rods and mis-used terms of the modern era. In the mid 1800s Charles Darwin and Alfred Wallace independently described a process called Natural Selection, one of the components of how evolution works. With the discovery and study of genetics and other disciplines, it is clear that random gene mutation and other factors are also involved. Natural selection works on individuals but the effects are seen in populations.This is due to variation in offspring having differential survival based on varying environmental factors that come in to play. Everything from color, to behavior, to body shape and physiology, are all effected by short- and long-term selection pressures that result in some populations of a species looking, behaving, and/or surviving in different ways than others. Some of these accumulated differences may eventually lead to new species. Here’s a good introduction to evolution.


An organism that no longer exists on the planet and is (at this point, anyway) unable to reappear again. Extinction is natural and an important component of the process of evolution. The fossil record helps evolutionary biologists record the appearance and disappearance of species, families, orders, and phyla of organisms over the 3.5 million years that living organisms have been on earth. Some geologic periods have seen massive events where enormous numbers of species became extinct while others survived and gave rise to new species. There appears to be a “background rate” of extinction through time. However, conservationists such as E.O. Wilson note that in the past few thousand years, more species are going extinct than during any of the great extinction events in the earth’s history. And today, there are fewer natural habitats for new species to evolve. Here’s one of his many essays and books.


A species that has lost one or more of its populations, typically within an artificial boundary (like a county, state, or country), even though populations exist elsewhere. Black Racers may be extirpated soon in Berkshire County while Timber Rattlesnakes may be extirpated from Massachusetts in the near future. Both still persist in other states. Contrast with the term: extinct.


Fangs are highly modified and mostly hollow teeth connected to venom glands through ducts. They function as an efficient method to deliver venom. Our Rattlesnake and Copperhead lack upper tooth rows, but instead have fangs on each side that are so large, they are folded back when not in use (which is most of the time).


Describes an organism that lives underground, as opposed to terrestrial (on the surface), arboreal (in trees), sub-nivean (beneath the snow), or aquatic (in water), for example.


The generic term for any female snake that has mated and will be either laying eggs (oviparous) or giving birth to free-living young (viviparous). The term “pregnancy” has the same meaning, but is typically used only for humans and other mammals.


Many (probably most) snake species exhibit Indeterminate Growth, where the individual grows (sometimes imperceptibly) throughout their lives. Other snakes may display Determinate Growth, where there is a limit to the final length it may attain.


Newborn reptiles that just emerged from an egg. None of our snakes appear to build nests, so hatchling or neonate are appropriate terms for newborns. “Snakeling” is often used for young snakes, but juvenile is the preferred term.


A wildlife management technique that rapidly increases the growth of young (typically newborn) animals so they can be released back into natural conditions with reduced likelihood of predation. For snakes, the process includes providing optimal temperature, plenty of food, and veterinary care, if needed. For many species mortality is highest for young individuals. This method has proven useful in such diverse animals as Bald eagles, Redbelly turtles, Atlantic salmon, and now Rattlesnakes.

Hemipenes (hem-E-pEEnz)

Male reproductive organ of snakes (and lizards). It is a bifurcated structure with two functioning sides. Males only use one side at a time, but Gartersnakes have been observed to switch sides in subsequent matings. (Singular: hemipenis).

Herps (Herptile)

This term commonly denotes both amphibians and reptiles, following Linnaeus’ lumping of the two groups in his 18th C publications. The study of either or both groups is called Herpetology and even though these two clades of vertebrates have little in common, herpetologists generally resist separating them into two disciplines. 

Hibernation (see also, Brumation)

In winter, non-migratory animals either continue their day-to-day activities or enter some sort of dormancy. For mammals, the extreme is hibernation, a state in which physiology is dramatically altered (including respiration, heart rate, body temperature, cellular respiration, and more). In Western Massachusetts, only bats, woodchuck, and jumping mice are “true” hibernators. Other mammals, such as bears, reach a reduced state of activity, slowing some bodily functions (like pooping!), but can become active if conditions require. Others, like chipmunks, vary in their response to cold and deep snow: some remain active most of the time, raiding bird feeders and other food sources, while other individuals store ample amounts of food in underground chambers and remain more or less active, but unseen by us. 


The towns and villages that rest on the Berkshire Plateau and known to harbor fascinating people who must contend with an extra season every year: spring, summer, fall, winter, and mud season. The Hilltowns include such diverse entities as Florida, Savoy, Windsor, Hinsdale, Washington, Becket, Otis, and Sandisfield.

Keystone Species

While the study of Natural History suggests that all species are equal, it turns out that some species may be "more equal" than others. This is due to their ability to dramatically alter ecological communities such that many other species are affected, either negatively or positively. Beavers have a profound effect upon wetlands improving conditions for such diverse species as great blue herons and watersnakes. Especially when at high populations, whitetail deer are well known to suppress tree seedling survival, thus changing forest types that could reduce survivorship to such species as timber rattlesnake and wood thrush.

Leaf Basking

A behavior that allows snakes to accomplish two seemingly opposite requirements: hiding from predators and exposing parts of their body to solar radiation.

Length, Total

Measurement from tip of snout to tip of tail. Many snakes have damaged tails due to attempted predation or other incidents. Therefore, many biologists prefer the snout-vent length instead, as a more consistent measure of size.

Length, Snout-Vent

Measurement from the tip of the snout to the far end of the anal plate (the scale that covers the cloaca). It's not easy to accurately measure a snake and visual estimates are often unreliable.

Loreal Pit (or Pit Organ). 

Externally, an opening between the eye and nostril in Pit Vipers that leads to a chamber that ends with a series of complex cells and tissues. These cells allow a snake to detect infrared radiation, producing a thermal image of its surroundings. This, of course, is incredibly valuable to a nocturnal hunter or a snake that may look for food inside hollow logs or dark crevices. 

Mimicry, Batesian

Formulated by Henry Bates, it is the accumulated adaptations of a tasty species (the mimic) enabling it to resemble a noxious species (the model) in appearance, behavior, or other aspects of its natural history. The presumed goal is to survive or avoid a potential predator. Are members of the milksnake group mimics of Copperheads or other venomous species in North, Central, and, South America? See the Milksnake page for more discussion and references. Is tail vibration in some North American snakes auditory mimicry? 


The first stage of a snake’s life, between birth and its first shedding, which can happen from a week old to as much as a year after birth. After the first shedding it’s called a juvenile. When a snake becomes sexually mature, it’s an adult.

Neotropical Migrants

A fascinating group of feathered reptiles (birds) that live in the new world tropics from the Amazon basin to central Mexico. Each spring individuals migrate thousands of miles to exploit rich feeding and nesting grounds in temperate North America where they also have up to 18 hours of sunlight each day allowing some to produce two broods of young per year. Shortly after raising their young, these birds typically head right back home to the tropics. Examples include most warblers, thrushes, orioles, and tanagers.


Active at night, between dusk and dawn.

Ontogenetic Change

The process that produces different appearance (morphology), behaviors, activities, physiology, or internal changes between birth and adulthood.  See the Black Racer and Eastern Ratsnake pages.


From the Greek name for snakes: Ophidians. Ophidophobia is a syndrome for those people who have an unreasonable fear of snakes. Not to be confused with “snake-haters” — people who just can’t stand them. Though there is a wide variation in responses, Ophidiophobes cannot bear even to look at a picture of snake, never mind a shed skin, or worse, a live animal. Don’t chase people with snakes; it’s bad for the snake.


Producing shelled eggs.


There is variation in how snakes spend the winter. Some species congregate at underground chambers called “dens.”  Other species seek shelter alone while some spend the winter in association with entirely different animals (like ants, or salamanders). There is still much to learn about this aspect of snake biology.

Patterns on Snakes

Stripes run the length of a snake, from nose to tail. Bands and crossbands are horizontal to the snake’s head, typically running from one side, up over the top, and down the other side. Blotches are incomplete bands, on the top or sides. Spots are small, roundish marks that can be scattered anywhere on the body.

Pit Organ

See Loreal Pit.


Passive Integrated Transponders. Also called Microchips in the pet industry. This widely used technology injects an electronic capsule under the skin that allows for identification of individual animals (from pets to pythons). A scanner (also called a receiver or transceiver) is used to send a signal to the tag, activating a response that relays the identification code back to the scanner. Since the PIT Tag has no battery, it can last indefinitely.


Generally, birds of prey whose evolutionary adaptations include specialized curved upper mandibles for tearing flesh and strong, grasping feet with talons for holding and/or carrying their prey. Diurnal raptors in Western Mass are the hawks (including eagles), falcons, and osprey. Nocturnal raptors are the owls, some of which are active in the daytime!


Attaching a transmitter to a free-ranging animal for repeatedly locating it by using an antenna and receiver. Developed back in the mid 20th century, early units were large, but could be made into a collar for big game like deer, mountain lions, and turtles. The advent of micro-electronics has revolutionized field biology allowing for smaller devices, some even fit on large insects. In snakes, radio transmitters are typically inserted into the body cavity surgically, then removed after the fieldwork is completed. Transmitters lasting one or two years are most commonly used.


A structure unique to New World Pit Vipers, the rattle consists of interlocking segments of keratin (similar to the outer layer of the skin). At birth, neonates have a single segment, called the prebutton; they shed this sheath within two weeks and the first rattle (the button) is revealed. With each shedding event, a new segment is added at the base of the rattle. Long rattle strings are uncommon as the segments are relatively brittle and easily lost as snakes crawl along rocks or rough vegetation. With remarkably long-working muscles rattlesnakes vigorously shake their tail, causing the segments to rub against each other, thus producing the sound.


Many venomous and non-venomous snakes around the world vibrate their tails as part of their defense repertoire. The sound made by actual rattlesnakes comes from the loose rattle segments hitting each other when the tail is shaken. When non-rattlesnakes rattle their (normal) tails and it is done against dried leaves, gravel, or a stone wall, the sound is a pretty good imitation of a rattlesnake—assuming you’ve never heard a rattlesnake before. Is this “auditory mimicry,” a sound attractant to lure potential prey, or are their other functions of tail vibrating?


A nickname often given to our Timber Rattlesnake, or any species of rattlesnake. However, many people incorrectly call any snake a rattler, especially those species that vibrate their tails, even if they lack actual rattles and are nonvenomous.  


Any of 32, or so, species of Pit Vipers that have a unique structure at the end of the tail. Rattlesnakes are only found in the New World, from southern Canada to northern South America. Early European naturalists were fascinated by such an animal and thus began a rich and interesting lore that continues today.

Redbelly Racer

A Berkshire-ism, for sure! I’ve never heard this term anywhere else and don’t even know what species is indicated. The Redbelly is a tiny, fossorial snake (less than 15” total length) that remains out of sight most of the time, while the Black Racer is big, day-active, and grows to almost five feet long. Any hybrid between them would require extraterrestrial intervention! 

Scale, Anal Plate

The enlarged scale on the underside of a snake that covers the cloaca. It is the point that marks the end of the body and the beginning of the tail.

Scale, Head

A series of paired and enlarged scales that cover the head of most snakes. Along with those on the side of the face, head scales are important characters distinguishing related species and geographically distinct populations.

Scale, Keeled

Dorsal body scales that have a raised ridge running down the center. Possible functions include more surface area to enhance swimming, climbing, thermoregulation, or moisture collection.

Scale Rows

Round as they are, snakes have a series of scales that cover the top of their body and meet the ventral scales. These scales are in regular rows and their number at certain body locations (neck, midbody, near the cloaca) show differences between related species and variation between populations of the same species.

Scale, Smooth

Dorsal body scales with no central ridge.

Scale, Ventral

These are the enlarged scales on the underside of a snake. On the belly, the ventrals are typically single; the ones under the tail (called the subcaudals) are often paired. Variation and damage to these scales are common. Field biologists often snip small sections from certain ventrals to produce a permanent mark for long-term identification. Just recently, Dr. William S. Brown at Skidmore College recently found a shed skin from Timber Rattlesnakes that he had marked thirty years earlier.

Sexual Dimorphism

The (often) obvious differences between adult males and females of the same species. In deer, it’s really obvious (antlers!), while in snakes it’s a bit subtle. Total length, snout-vent length, subcaudal scale counts, and the presence of certain scale modifications are the most common differences found between male and female snakes.


The mountain range that borders the western edge of Massachusetts. It is also the western boundary for the Housatonic River Valley. Most people think of this north-south range as the Berkshire Mountains, though that is not accurate.


Snake teeth are sharp, pointed, and curved back towards the rear of the mouth. They function to grab and retain prey. By alternately lifting the left and right sides of their skull, snakes are able to move food down their throats; some describe it as the snake pulling itself over its food. Teeth are regularly broken and/or lost and are replaced continually. Careful observers often find teeth in snake scat (ok, poop) along with other indigestible remains. Snakes are missing front teeth in their upper and lower jaws. This gives them two tooth rows on top and two rows on the bottom. Snakes also have two rows of teeth on the roof of their mouth, for a total of six rows of teeth. In our venomous snakes, the upper two rows of teeth are reduced to a single specialized tooth, the fang; they still have the other four rows of teeth.


An animal with a backbone, excluding fish. Tetrapods include amphibians, reptiles (including birds), and mammals. All have paired, bony limbs, lost through evolution, in snakes.


A remarkable organ allowing snakes unprecedented access to a rich world of chemical signals. Being bifurcated (forked) allows a snakes, even in darkness, to determine left and right (or up and down) variations in scents that allow it to decipher the presence of a female snake, prey, moisture gradient, and even the direction of travel of a recently passed animal.

Venomous (vs Poisonous)

In general, venom is injected via some structure such as fangs, a modified ovipositor (bees), or an appendage (scorpions). Poison is ingested or absorbed. So, a copperhead is venomous while an Amanita fungus is poisonous.

Vent (see Cloaca)


Giving birth to free-living young. Often they are born covered in a thin, transparent membrane that soon ruptures.

Western Massachusetts

The area encompassing approximately 610,000 acres (about 35 by 60 miles) including 101 communities in these four counties: Hampden, Hampshire, Franklin, and Berkshire. 

  © Tom Tyning 2013