SNAKES AND LIZARDS OF MINNESOTA TABLE OF CONTENTS Acknowledgments . 4 Introduction . 6 Key to Minnesota’s Snakes . 24 Common Gartersnake . 26 Common Watersnake . 28 DeKay’s Brownsnake . 30 Eastern Hog‑nosed Snake . 32 Gophersnake . 34 Lined Snake . 36 Massasauga . 38 Milksnake . 40 North American Racer . 42 Plains Gartersnake . 44 Plains Hog‑nosed Snake . 46 Red‑bellied Snake . 48 Ring‑necked Snake . 50 Smooth Greensnake . 52 Timber Rattlesnake . 54 Western Foxsnake . 56 Western Ratsnake . 58 Key to Minnesota’s Lizards . 61 Common Five‑lined Skink . .. 62 Prairie Skink . 64 Six‑lined Racerunner . 66 Glossary . 68 Appendix . 70 Help Minnesota’s Wildlife! . 71 Cover photos: Timber rattlesnakes photograph by Barb Perry . Common five‑lined skink photograph by Carol Hall . Left: Park naturalist holding gophersnake . Photograph by Deborah Rose . ACKNOWLEDGMENTS Text Rebecca Christoffel, PhD, Contractor Jaime Edwards, Department of Natural Resources (DNR) Nongame Wildlife Specialist Barb Perry, DNR Nongame Wildlife Technician Snakes and Lizards Design of Minnesota Creative Services Unit, DNR Operation Services Division Editing Carol Hall, DNR Minnesota Biological Survey (MBS), Herpetologist Liz Harper, DNR Ecological and Water Resources (EWR), Assistant Central Regional Manager Erica Hoagland, DNR EWR, Nongame Wildlife Specialist Tim Koppelman, DNR Fish and Wildlife, Assistant Area Wildlife Manager Jeff LeClere, DNR, MBS, Animal Survey Specialist John Moriarity, Senior Manager of Wildlife, Three Rivers Park District Pam Perry, DNR, EWR, Nongame Wildlife Lake Specialist (Retired) This booklet was funded through a State Wildlife Grant and the Nongame Wildlife Program, DNR Ecological and Water Resources Division . Thank you for your contributions! See inside back cover . ECOLOGICAL AND WATER RESOURCES INTRODUCTION is understandable in Minnesota, spend most of the active season . In many snakes and lizards, particularly Throughout time, snakes have since we only have three lizard fall, snakes and lizards move back to those that live in dry, sandy or rocky caused fear in many people, while species, and all have a very short their wintering areas, or hibernacula. habitat, become nocturnal, where evoking awe in others . Either way, active season . This “migratory” behavior is more they are active primarily at night, or snakes are often misunderstood common with Minnesota’s snakes crepuscular, where they are active and under‑appreciated . In fact, General Biology than lizards . May is the peak primarily at dawn and dusk . This many people kill snakes simply Minnesota has seventeen snake time for spring movements and change in daily activity period allows because they fear and dislike them, species, two of which are rattle‑ September for fall movements, ectothermic animals, such as snakes and don’t understand what snakes snakes, and three lizard species . making them the peak months for and lizards, to avoid overheating contribute to our world . Snakes and lizards are classified as most snake‑human encounters . during the extreme temperatures of reptiles, which are characterized However, the peak encounter time summer days . This human persecution has led by having scaly skin and being for timber rattlesnakes in Minnesota to the decline of many snake ectothermic (cold‑blooded) . Because is July through August . A few key differences between species, including those found in the body temperature of these snakes and lizards relate to their Minnesota . Fear of snakes is a learned animals is largely controlled by the In addition to seasonal active anatomy . Minnesota’s lizards have behavior, and is often heightened temperature of their surroundings, periods, snakes and lizards also legs, external ear openings, and by media misrepresentation and they are typically only active in have daily activity patterns . Many eyelids, while snakes lack all of these sensationalism . As we learn more Minnesota from April through late snakes and lizards are diurnal, being features . Instead of eyelids, snakes about snakes and their benefits, October . During the winter, they active during the day, particularly in have clear scales, called spectacles, our willingness to coexist with move underground, below the spring and fall when temperatures which cover and protect their eyes . them increases . frost line, and become inactive, are cooler . During the summer, or hibernate . Like snakes, lizards are often unappreciated and somewhat Once snakes and lizards emerge feared by people in the upper from hibernation in spring, they Midwest simply because they are generally will move away from dens so unfamiliar . This lack of direct or other overwintering areas to and indirect experience with lizards hunting areas, where they will Carol Hall Erica Hoagland Erica 6 Snakes and Lizards of Minnesota Snakes and Lizards of Minnesota 7 Skin Snakes and lizards shed their scales, Prior to shedding, the skin appears example, hatchling North American One common misconception about or skin, as a way to allow for growth, faded and dull, especially with racers have blotched patterning, snakes and lizards is that they feel keep their bodies free of mites snakes . Because snakes shed the somewhat similar to a milksnake . slimy . On the contrary, they have and other parasites, and to replace scale covering each eye, their Once the racers are about three dry, scaly skin which can often feel old, worn skin . Skin can be shed in eyes may appear milky as the years old, they will have developed rough . Reptile scales are made of one piece, which typically occurs scales loosen (Figure 3) . Snakes typical adult coloration of solid slate keratin, the same material as human in snakes, or it can flake off, which are particularly vulnerable during gray or blue on their back, with a fingernails . Scales help snakes and is more common in lizards . Snakes this time due to their vision being yellow underside . lizards retain moisture, protect their shed their skin by rubbing their nose impaired, and they may behave more bodies from wear and tear on a rock or some other defensively when encountered . Skin variations can make identifi‑ from their sometimes harsh rough surface to break After shedding, the animal’s skin cation challenging; however, each environments, and provide Shedding the skin . They then crawl color and patterning are bright and species has a scale composition colors and patterns that may typically occurs out of the old skin, leaving clear, and may even appear glossy . (color and/or pattern) that is allow them to blend in with once or twice the shed skin inside out typically characteristic for that their natural surroundings per year. (Figure 2) . Freshly shed The number, shape, color and species (Figure 4) . (cryptic coloration) . Scales snakeskins can be used to patterning of scales can vary also help snakes move as identify different species considerably between species, The dorsal pattern on the backs they crawl and climb . Scales can be because you can often still see the and often within a species . There of snakes and lizards is one smooth or keeled (Figure 1), having pattern and scale composition . can be differences in patterns characteristic used for identification . a ridge along the centerline similar Young snakes and lizards shed more and colors among geographic These patterns can be in the form to the pointed keel of a boat . In frequently than adults, sometimes regions as well as at a more local of blotches, vertical lines/stripes some species, scales are modified to two to three times during the active level . Colors and patterns can also running from head to tail, horizontal form different structures, such as a season . However, once they reach change as the animal matures . For bars/bands running across the body, rattlesnake’s rattle . maturity, shedding typically occurs only once or twice per year . Smooth Keeled James Gerholdt James Figure 2 . Plains gartersnake starting to Figure 1 . Scale comparison . Hoaglund Erica shed skin . Figure 3 . Gophersnake prior to shedding . Notice opaque, milky color of eye . 8 Snakes and Lizards of Minnesota Snakes and Lizards of Minnesota 9 Venomous Verses Eyes also differ between the Nonvenomous Snakes two groups . Rattlesnakes have in Minnesota elliptical, or cat’s eye pupils, but our Many people believe that some of nonvenomous species have round Minnesota’s snakes are poisonous . pupils (Figure 7) . A third difference This is not accurate . Poison is relates to the scale pattern on the generally ingested and intended to ventral tail surface . Minnesota’s ward off or kill predators whereas, rattlesnakes have single ventral venom is a type of toxin that is scales on their tail, whereas, our . injected into prey to help subdue nonvenomous snakes have divided and/or kill it prior to consumption . ventral scales on their tail (Figure 5) . Minnesota’s rattlesnakes are Minnesota DNR Minnesota considered venomous, rather than Both of Minnesota’s rattlesnakes Figure 4 . Snake skin patterns left to right: blotched (milksnake), lined or striped poisonous, because they deliver their are called pit vipers because they (gartersnake), banded (timber rattlesnake) . venom by injection, and their flesh is have a set of loreal or heat‑sensing not poisonous to another animal if it pits located between their eyes and is eaten . nostrils (Figure 7) . Nonvenomous or no pattern (solid) . Some snakes The anal plate is either singular or snakes in Minnesota lack these have patterns on their belly that divided in snakes (Figure 5) . Minnesota has two venomous snakes, pits . Lastly, our rattlesnakes have are used for identification . These both of which are rattlesnakes . triangular‑shaped heads that are patterns include a checker board, a In some snake species, the number of There are several characteristics noticeably wider than their necks, series of half moons, or solid . scale rows and placement of patterns that differentiate our rattlesnakes while our nonvenomous snakes or colors on these rows can be a key from our 15 nonvenomous snake have rounded heads that are The anal plate is often used in snake characteristic for identification . This species . Our two rattlesnakes essentially the same width as their identification .