Amphibians & Reptiles – Snakes

Night Hunters

Nocturnal animals are most active at night. These animals have developed senses, abilities, and hunting strategies over millennia to exploit the nighttime hours, living and hunting in the same habitats as daytime species. Many nocturnal hunters are more energy efficient in cooler temperatures; some have darker coloration to more easily blend in; and some have jagged silhouettes making them harder to spot.

^{_{Gaboon Viper, Bitis gabonica, showing pit by DonArnold; Copperhead, Agkistrodon contortrix, showing pit by DonArnold; Spider at night by Masse-j, Jul 2015}}

There are advantages to living at a time of day when there is less general activity. Predators may become more active at night if their prey is nocturnal. Ambush hunters may find prey is not as nimble in the dark and cannot escape as easily. Nighttime hunters have less competition for the same species hunted in the daytime. No animal can see in complete darkness, but let’s take a look at some of the adaptations that allow nocturnal species to distinguish detail and overall clarity as light levels ebb.

Strategies and senses involved in detecting prey are numerous, whether an animal is a daytime or nighttime hunter. One of the most often recognized is vision – the ability to see prey. Eyes have two types of cells, rod cells and cone cells, that convert light into nerve signals to the brain. Cone cells, clustered in the center of the retina, work best in bright light to reveal detail and color. Rod cells surround the outside of the retina and can detect motion in black-and-white or low-light. Some species have an additional reflective layer, the tapetum lucidum, located behind the retina. It acts as a mirror to reflect any light coming through the eye back into the eye, effectively making any image brighter.

_{Barn Owl, Tyto alba, by DonArnold; American Alligator, Alligator mississippiensis, by DonArnold}

Owls have large, forward-facing eyes with binocular vision and depth perception. Their eyes can pick up light 100 times dimmer than what humans can see. Big cats, such as leopards, can see 6 to 8 times better than people can and use stealth to take down prey bigger than themselves. The American alligator and Nile crocodile are ambush hunters with excellent low light level eyesight, being able to detect slight movements and silhouettes on shorelines. All of these animals use the extra rods in their large eyes to detect movement within short striking distances.

_{Red fox, Vulpes vulpes, showing tall ears by DonArnold}

Hearing involves the ability to pick up noise from soft to loud levels. Fox and coyote can hear sound up to two miles away. Their ears can move independently to almost any angle and are used to triangulate sound so they can pinpoint the source. They are especially attuned to higher frequency noise that is often made by smaller rodents or noises made from prey located under snow, dirt, or brush. Owl ears are asymmetrical, meaning they are not balanced on either side of the head. Sounds are heard by each ear at slightly different times, again allowing the bird to triangulate and identify the exact location of their quarry.

_{Great horned owl, Bubo virginianus, on night flight by Art Siegel, Feb 2007}

Hearing also involves the ability to mask sounds so others cannot locate the predator. For owls, flight feathers have ragged edges and velvety surfaces, both adaptations making the air flow through and over their feathers with little or no noise. This makes the owl hard to detect by the prey they are hunting. Large, well-padded paws on big cats provide them with the ability to make slow, quiet approaches to their prey.

Many predators have senses that work any time of day, but choose nighttime hours due to cooler temperatures and less competition. Sharks have ampullae, organs that detect electric fields which are produced anytime a muscle is contracted by an animal. Cat’s whiskers and body hair on scorpions detect vibrations in the ground or the air created by other creatures’ movements. Pit vipers, pythons, and boas all have heat sensing abilities that can detect minute temperature changes close by as prey comes within striking range. Crocodiles have pressure sensitive scales to detect water disturbances such as prey coming to drink at the water’s edge. Bats use echolocation, sending out their own sound waves that bounce back to them after hitting an object, identifying size, shape, and distance to that object. Forest bats use higher frequencies with shorter wavelengths that provide detail at short range, while open grassland bats use longer wavelengths that provide detail at farther distances.

Many species have abilities to navigate, hunt, and avoid danger themselves in the darker hours. However, light pollution makes these natural abilities harder or impossible to use. We can respect the nighttime species by turning off any unnecessary outside lights at night, so we can enjoy observing more of those same nighttime wonders. Learn more at the Jurica-Suchy Nature museum, or a nature center close to you.

To learn more about the following species or topics, click on the name to link to a previous blog:

American Alligator

Barn Owl & Great-Horned Owl

Great Horned Owl

Red Fox

Venomous Snakes Of Illinois

There are 40 snake species native to Illinois, and they are found in all types of habitat from woodlands and prairies to wetlands and urban areas. Of these, four species are venomous. A venomous snake is one that uses a chemical toxin to kill its prey. This internally developed chemical is delivered through a pair of hollow fangs in the upper jaw of the mouth. When the snake opens its mouth, the fangs drop down and venom is injected into the prey as the snake bites. The snake will then release the prey, waiting for the venom to kill it before swallowing the prey whole. Juveniles will inject less venom, but with the same potency as adults.

^{Pit viper Fang and Jaw Structure drawn by M Moran at Encyclopedia Britannica}

Venomous snakes in Illinois are all pit vipers, a sub-family of the Viperidae family of snakes. The pit, a large opening between the eye and the nostril, just above the upper lip, can detect heat given off by warm-blooded prey species. Their elliptically-shaped eyes is another characteristic that helps to identify venomous snakes.

^{Close-up of elliptical eye on Copperhead by Mark Dumont, Jun 2011}

^{Close-up of pit above upper lip on pit vipers, by Scott Ballard, IDNR}

Illinois venomous snakes are non-aggressive in nature, but will bite if cornered, harassed, or stepped on. Bites are usually not fatal in humans, but they can be quite painful, often resulting in swelling and possible infection. Vomiting, nausea, and tissue or nerve damage may also result. Anyone that is bitten should seek immediate medical attention.

^{Eastern Copperhead, Agkistrodon contortrix, by Peter Paplanus, Aug 2018}

^{Eastern Copperhead close-up, Agkistrodon contortrix, by Peter Paplanus, Apr 2021}

The Eastern Copperhead, Agkistrodon contortrix, lives in the southern third of Illinois on wooded hillsides, river bluffs with sandstone or limestone outcroppings, and along forest edges. During the hot summer months, they may also feed on the abundant rodent populations in meadows or near abandoned buildings. The copperhead is about four feet in length and has a light brown back with one to two dozen reddish-brown colored hourglass-shaped markings along the back. The top of their head is a brighter red-brown.

^{Northern Cottonmouth, Agkistrodon piscivorus, by Virginia State Park Service, May 2016}

^{Northern Cottonmouth flashing white, Agkistrodon piscivorus, by Peter Paplanus, Aug 2022}

The Northern Cottonmouth, Agkistrodon piscivorus, resides in far southern parts of Illinois, living in swamps, sloughs, and oxbow lakes. At five feet in length, this heavy-bodied snake is a uniform charcoal or dark olive color, with dark crossbands and a tan to gray belly. When disturbed, its response is to face its attacker and open its mouth widely, displaying the bright white interior, earning the name of cottonmouth.

^{Timber rattlesnake close-up, Crotalus horridus, by Peter Paplanus, Apr 2023}

^{Timber rattlesnake, Crotalus horridus, by Peter Paplanus, Apr 2023}

Timber rattlesnakes, Crotalus horridus, live in both southern and northern areas along the Mississippi River and Illinois River valleys. Usually found in heavy timber with rock outcrops or bluffs, this snake, up to six feet long, is marked by two dozen black crossbars down a gray-green-yellow back. Its belly is light-colored with dark edges, and it shows a dark strip behind each eye. Timber rattlesnakes will hunt in any areas where there is a large rodent population. They are listed as threatened since we have seen sharp declines in the populations in recent years.

^{Massasauga Rattlesnake, Sistrurus catenatus, by Peter Paplanus, Apr 2021}

^{Massasauga Rattlesnake close-up, Sistrurus catenatus, by Peter Paplanus, Apr 2021}

The Massasauga Rattlesnake, Sistrurus catenatus, is found in small numbers scattered across the state, mainly in prairie wetlands and river floodplains. Listed as endangered in the United States, it has become quite rare in Illinois with only a couple sightings annually for the past several years. Massasaugas are about two feet in length, with a gray to light brown back and 30-40 dark, bow-tie shaped markings. Four to seven darker rings cover the tail. Their main prey is small rodents.

Venomous snakes have small ranges, staying close to home for hunting and mating. Their main predators include humans, birds of prey, and other snakes. Many have been killed by people with an unfounded fear of these creatures. Although they play a major role in controlling rodent populations, there has been little concern shown over loss of habitat due to draining of wetlands and other urban development. Plan a visit to the Jurica-Suchy Nature Museum or a nature center near you to learn more about these mysterious, yet wonderous species.

Snake Defense

Snakes, with over 3,000 species worldwide, are one of the largest groups of reptiles. They are found on every continent except Antarctica and live in every type of habitat including freshwater and saltwater. They have numerous enemies and have developed defensive strategies enabling them to survive and prosper.

^{Catching a snake on the wing by CuriousLog, Jun 2007}

^{Red-shouldered hawk with snake by Don Loarie, Mar 2018}

^{Great Blue Heron eating snake by C Watts, Jan 202}2

Snakes must deal with threats from a wide range of animals. Bird species that prey on snakes include raptors, ravens, egrets , and storks. Nocturnal hunters, including owls, have excellent sight in low-light conditions and often hunt by spotting movement among foliage. Likewise, during daytime hours, red-tailed hawks and eagles can spot movement on the ground while soaring. Snakes are normally line-of-sight hunters, and are often unaware of threats from above, giving avian predators a distinct advantage.

_{^{American crocodile, Crocodylus acutus by Florida Fish and Wildlife, Feb 2021; Wolverine by Maia C, Aug 2012; Skunk by D Fletcher, May 2016}}

Most mammal predators are larger, more agile, and faster. Badger, wolverine, and racoon are all excellent climbers and may hunt from an elevated perch. Wolverine and skunk are also burrowers that will dig out their prey from underground. Snakes living in saltwater and freshwater environments are eaten by predators such as crocodiles and snapping turtles. In addition, some larger snake species regularly hunt smaller snakes.

^{Copperhead on dead leaves by Abbott Handerson Thayer, Mar 2022}

Snakes use a number of non-aggressive strategies to avoid confrontation and escape. Their best defense is to remain hidden, using colors and patterns to break up the outline of their body, allowing the snake to blend with the background foliage and be overlooked by any predators. Another passive strategy is balling, involving compressing their body into a tight coil or ball, typically with the head tucked in to protect this most vulnerable area. Playing dead is often an effective means to escape predation, honed to perfection by the Western hognose snake. This snake convulses its body, rolls onto its back, and lets its tongue loll out of its mouth. It may vomit or spew blood, release fecal matter or musk, all in its attempt to convince a potential predator that it is already dead and no longer appetizing.

^{Timber rattlesnake balled and hidden by Peter Paplanus, Apr 2022}

Mimicry is a development that has taken place in some species over long periods of time. Batesian mimicry is when a harmless species has evolved the coloration of a more dangerous species to fool a predator into leaving it alone. Scarlet kingsnakes of the southeastern United States are quite harmless but look very much like Eastern coral snakes, a venomous species in that same area. Auditory mimicry involves creating sounds used by more dangerous snakes. Fox snakes, found in deciduous forests, often vibrate their tails in leaf litter, making a buzzing noise very similar to the sounds made by rattlesnakes living in the same area.

^{Scarlet kingsnake by FWC Fish & Wildlife Research Institute, May 2015}

^{Eastern coral snake by FWC Fish & Wildlife Research Institute, Sep 2014}

Snakes often use one or more methods of intimidation. Bright display colors are found among many venomous species and serve as a warning to potential predators that this snake is dangerous. Another form of intimidation involves a snake inflating its body or a body part to make it look bigger. The puff adder inflates its whole body by filling its lung with air. Cobras hold their heads high and flare out an extra fold of skin on either side of their heads, commonly called “hooding.” Intimidation may also involve auditory cues including the rattling of a snake’s tail and the hiss emitted by cobras as they bring up their heads.

When the above strategies do not allow the snake to escape, most species will not hesitate to strike. Several species do not bite, striking with the nose or an open mouth; however, all venomous snakes will bite in self-defense, although they may not inject venom. A few species are able to spit venom, used purely as an act of self-defense, although if the venom targets an eye or nasal passage, the results can be extremely painful.

Snakes are some of the most interesting species with a lifestyle very different from our own. They have many strategies for keeping themselves safe from wild predators, and will be around for us to observe, learn about, and be fascinated by.

Desert Habitat, pt.3

In the past two blogs, we have explored deserts and the plants which inhabit them. Animals native to these habitats have general adaptations for coping with temperature extremes, aridity, and finding water, food, and shelter. Strategies include hunting during cooler hours including at dawn, dusk, or overnight; obtaining water from sources other than standing water; burrowing underground to avoid temperature spikes and solar radiation; ability to conserve water in their body; ability to dissipate body heat; and being well-camouflaged. Look for each of these adaptations in the following species that live in our desert regions.

Greater roadrunner, Geococcyx californianus, by Tony Cyphert, Sep 2018

Ord’s Kangaroo Rat, Dipodomys ordii, by Andy Teucher, Jun 2005

The greater roadrunner, Geococcyx californianus, can only fly for several seconds at a time, but can reach speeds up to 17mph when running. They hunt early in the morning, retiring to shade when temperatures heat up mid-morning. Water requirements are met from foods including grass and prickly pear cactus, plus prey that includes lizards, scorpions, and rattlesnakes. Roadrunners do not urinate, but can excrete salt and save the water. They have an un-feathered area under their chins used to dissipate body heat. Ord’s kangaroo rat, Dipodomys ordii, is another species that gets all of their water requirements from the seed they eat. Individuals live in underground burrows, coming out only at night to feed. They conserve water in their bodies and do not sweat or pant. They have many predators, but with a 9-foot jump and excellent hearing, they are hard to catch. Seeds are collected and stored in their burrows, and they will gain 50% more water from the underground humidity before being eaten.

Horned Toad, Phrynosomasp., by TJFrom AZ, May 2009

Gila monster, Heloderma suspectum , by Karla Kishinami, Apr 2012

Horned toads, Phrynosoma spp., are small, ant-eating lizards with thick scales to conserve water and deter predators. To escape a predator, these animals can squirt a directed stream of blood from their eyes up to five feet away. They are sandy-colored with undefined outlines allowing them to easily hide amid rocky outcrops. Normally active during the day, they can retreat to burrows or under rocks if temperatures become too hot. During winter, horned toads will spend a period of inactivity, called brumation, in underground burrows. The Gila monster, Heloderma suspectum, is another lizard with armor protected skin marked with black and pink coloration that camouflages them well in sandy soils. They shelter from daytime heat under rocks and shrubs, emerging in early morning or evening to hunt small mammals, lizards, insects, and bird eggs. One of only two venomous reptiles in North America, their venom adversely affects their prey’s nervous system. The short, thick tail stores water in fatty tissue for use when needed.

Tarantula, Aphonopelma sp., by Saguaro National Park, Nov 2020

Western coral snake, Micruroides euryxanthus, by Ashley Wahlberg, Apr 2016

The tarantula, Aphonopelma spp., shelters in deep burrows lined with silk to prevent the sand from caving in. They are nocturnal hunters of insects, arthropods, and small lizards with a bite that delivers a small amount of venom to stun their prey. Venom immediately starts to break down tissue to liquify the meat, allowing the spider to use sucking mouth parts to draw in its meal. The Western coral snake, Micruroides euryxanthus, is brightly colored with red-white-black-white banding and venom that is twice as deadly as most rattlesnakes. They are very secretive, living under rocks or buried in the sand. Coming out at night or on some overcast days, they hunt for lizards and other snakes. Venom causes rapid paralysis and respiratory failure, although due to their small size and small amount of venom injected, they are not a threat to humans.

Like many environments, a healthy desert community exists when plants, animals, and habitat are all present and undisturbed. With much of the life in deserts underground, walking off trails and driving off roads can negatively impact what is under the surface. Removing plants and rocks used for water and shelter is equally damaging. I encourage you to get out, observe, and enjoy this unique habitat, or research many of the fun and interesting adaptations at a local natural history museum.

^{Pictures above clockwise: Bark scorpion by Josh More, May 2014; Cactus wren by Mick Thompson, Feb 2019; Jackrabbit, by Mark Gunn, Mar 2014; Javelina, Sonora Desert, by Richard Bonser, Jan 2005; Tarantula hawk wasp by Jim Mulhaupt, May 2010; Sonoran mud turtle by Grigory Heaton, Sep 2022; Round tailed ground squirrel by Wendy Miller, May 2022; Hoary bat by Michael Pennay, Sep 2009; Cactus deermouse by J.N.Stuart, Oct 2011}

Illinois State Symbols, pt.2

Last week, we learned about state symbols covering many of the natural wonders found in Illinois. The following paragraphs describe the state symbols for the animals that have earned recognition.

In the early 1900s, the first forest preserves in the nation were in Chicago setting aside rare habitats that would protect animal and plant diversity. Over 94% of Illinois land areas are considered rural, including 1.4 million acres of wetlands. The Illinois State Fish, the Bluegill, Lepomis macrochirus, is found in lakes and ponds and was selected by schoolchildren in 1986. Also known as bream or brim, the name refers to the bright blue gill covers sported by the male.

Eastern tiger salamander, Ambystoma tigrinum, by John P Clare, Apr 2013

The State Amphibian is the Eastern Tiger Salamander, Ambystoma tigrinum, the largest terrestrial salamander in Illinois. This State Amphibian and State Reptile were voted on by citizens in 2004 and approved by the Illinois General Assembly in 2005. It has a large head and dark body with irregular yellow blotches. It can be found everywhere in the state, although it is uncommon in large agricultural areas.

Painted turtle by Victoria Pickering, May 2020

Eastern Milk Snake, Lampropeltis triangulum, by Peter Paplanus, May 2019

There are two reptiles recognized in Illinois. The State Reptile is the Painted Turtle, Chrysemys picta, a species found in all aquatic habitats in Illinois. It is dark olive with yellow, red, or orange markings covering the plastron, forelegs, and both sides of the head. In addition, we have a State Snake, the Eastern Milk Snake, Lampropeltis triangulum triangulum. Its body is gray covered with large brown blotches with black borders. Milk snakes average 24″-43″ long, and live in fields, woodlands, and rocky areas. When agitated, the snake will vibrate its tail and hiss before striking. They are constrictors that feed on small mammals.

Monarch, Danaus plexippus, on swamp milkweed by Anita Gould, Aug 2005

Pollinator species are important to the agricultural industry. Plants of all kinds require pollination in order to set seed. Insects are one of the most important groups of pollinators. Butterflies, bees, wasps, flies, ants, beetles and many more all feed on nectar offered by plants. In the process, they collect pollen on their bodies, sometimes to eat and other times inadvertently as they push through the flower to obtain nectar. Pollen is then transferred to other plants the insect visits. The State Insect is the Monarch Butterfly, Danaus plexippus, chosen by schoolchildren in 1975. Monarchs lay eggs and feed on many of the state’s native milkweed species. The butterfly’s orange coloring is a warning to predators not to attempt to eat a monarch which consumes, processes, and stores toxins from milkweed plants for its own defense.

Cardinal, Cardinalis cardinals, by Marcel Milliard, Dec 2020

White-tailed deer in corn, Matthew Paulson, Jul 2014

The State Bird is the Northern Cardinal, Cardinalis cardinalis. Selected by schoolchildren in 1929, the cardinal beat out several other choices including bluebird, meadowlark, bobwhite, and oriole. The cardinal, a medium-sized songbird, is known for the males’ bright red feathers. It prefers the forest edge where it can enjoy both prairie and woodland resources for hunting and shelter, but is often seen in backyards. The State Animal, White-tailed Deer, Odocoileus virginianus, also enjoys living along the forest edge. Selected in 1980, deer have some amazing abilities. They are able to run at 40 miles per hour and jump over a 9-foot high fence. They are excellent swimmers, traveling 13 miles-per-hour in the water. Native Americans and settlers both heavily relied on deer for buckskin clothing and food.

State symbols are representative of items and species that are present in our state. Take the opportunity to observe these natural wonders on your next outdoor adventure.

Snake Monitoring

Some days I spend hours grabbing snakes! As a snake monitor, I am one of several stewards in this area leading groups that monitor snakes. Our goals are to learn what species live here, their population size, and what areas they inhabit. We are using this data, as well as other related information, to assist in making habitat management decisions.

Wildlife monitoring activities for any species are designed based on prior knowledge of when and where a species may be found and what kinds of activities we might observe. For snakes, we identify possible sites based on several factors: being away from human activities, having access to food, water, and shelter for overnight and bad weather. We set out numerous snake boards. A snake board is a piece of rubber, wood or metal approximately two square feet in size and heavy enough that it will not be moved by wind or animals. A line of these are laid out in the observation area, about one every 8-10 yards. I use three boards at each of my dozen or so sites, but there can be 1 to many used.

*Storeria dekayi*, Midland Brown Snake by Janice Sommer, 2018

Snakes are ectotherms, meaning they must obtain heat from their surroundings. Snakes require heat to perform any action including moving, hunting and digestion. Snake boards are generally placed in sunny areas. This creates a spot where a snake can spend a few safe and sheltered hours absorbing heat that will allow them to hunt, eat and digest a meal. When they are warm enough, they will leave the board area, complete their hunting or other movements. They usually spend the night under rocks or logs in a close-by and safe place and return again the next day.

Monitors usually work in pairs. When we visit a site, we will record date, time, and weather conditions. One monitor lifts the board and both monitors capture any snakes that are present, placing them into a soft, cloth bag. As each snake is removed from the bag, we record the species, weight, length and any identifying marks.

Several pictures are taken of each one, and then they are released. They usually disappear quickly into the underbrush, but may not go far and may return to the board after we are gone. Observations are made at least weekly, and are varied by time of day or weather conditions in order to have data across a wide spectrum of factors.

We have a wide variety of questions, and we are always adding more to the list. Identifying what data to collect to provide answers, helps determine and refine our procedures. Questions range from statistical to curious such as what snakes do we find in DuPage County, where do they live, what do they eat, can they swim, what restoration activities affect them and how, what management practices need to take them into consideration. Collected data is used by scientists, teachers and stewards as we learn more about our own environment and how to manage its health.

Garter Snakes

At this time of year, as soon as the daytime temperatures start to reach into the forties and above, we begin to see snakes coming out of their winter dens. Two common snakes in DuPage County are both garter snakes, from the genus Thamnophis which includes 30 species worldwide.

The Eastern Garter Snake, Thamnophis sirtalis and the Plains Garter Snake, Thamnophis radix spend the winter in underground dens containing several dozen to several hundreds of individuals. Winter is a period of dormancy where these snakes enter brumation, an extreme slowing down of their metabolism.

Eastern Garter Snake, *Thamnophis sirtalis*, by DonArnold

A garter can be up to 30″ long, black/brown backs, yellow stripes on their sides and a gray-green belly. Usually found in meadows, light forests, marshes and vacant lots, they enjoy a warm spot such as open rocky/paved surfaces warmed by sunlight or hanging out in bushes or logs in the sun. Their meals include insects, earthworms, slugs and fish. Nights are spent under logs, rocks or leaf litter protected from wind and rain.

There are a variety of methods used to study snake species, one of which involves using cover boards. Boards are approximately two square feet, made of plywood, aluminum siding or heavy rubber. These are placed in likely spots where snakes will be found. The snakes use the boards during the day for shelter, rest and warmth. When snakes are found under the boards we identify each snake, weigh and measure it, take lots of pictures and note any markings or injuries. We also record location, weather, time of day and any activity observed. Finding a variety of individuals helps to establish population numbers; finding the same individuals more than once helps to identify whether snakes are moving to different locales during the year.