Natural Notes: Cook County and Northern Illinois Herpetology

This blog post consists of notes from a lecture on herpetology in Cook County, Illinois as part of a Master Naturalist Training Series.  The speaker was Jake Huffman, a naturalist with Sand Ridge Nature Center in the Forest Preserves of Cook County.  The lecture took place at Sand Ridge Nature Center in South Holland on Friday, September 11, 2015.  


Introduction/Overview
The class Amphibia consists of frogs, toads, newts, and salamanders.   There are also other groups of animals that fall within class Amphibia, but they are not found in Cook County.  The word "Amphibia" is derived from Greek to mean "dual lives."

Recommended field guides (titles) for identifying local amphibian include:

• Amphibians and Reptiles of the Great Lakes Region
• The Illinois Natural History Survey
• Common Toads and Frogs of the Chicago Region (published by the Field Museum)

Some amphibians in Cook County are somewhat unusual.  Newts are a special subgroup of salamanders that have a strange lifecycle (discussed below).  Tree frogs such as the Eastern Gray Treefrog (Hyla versicolor) do not live in ponds as most other frogs do, but rather they live in trees and among terrestrial vegetation, although they do require ponds to breed and lay eggs upon.

Toads (Anazyris spp.) have a paratoid gland which is used for defense.

Bull Frogs (Lithobates catesbeianus) and Green Frogs (Rana clamitans) have subtle difference in morphology.  Adult bull frogs are much larger than adult green frogs.  Bull frogs lack a dorsal and lateral ridges and they have a much more rounded mouth than those of green frogs.

Snapping Turtles (Chelydra serpetina) (see Figure 1) are often found covered in leeches when coming out to lay eggs in the spring, a testament to their highly aquatic lifestyle.

Figure 1:  A mature snapping turtle.
Photo credits:  Carol Kim/Forest Preserves of Cook County

With turtles in general, eggs that hatch in the spring were usually a clutch from the previous year whereas eggs that hatch in the fall were most likely laid in the spring of that same year.  Spring-born turtles actually hatched from their eggs late in the season the previous year and then went into hibernation before emerging to the surface.  In Illinois, most turtle species are associated with aquatic habitats.

Defense Mechanisms
Different species of reptiles and amphibians in Illinois have different defense mechanisms.  Common defense strategies employed by reptiles include rattling or vibrating its tail, releasing a musk (foul odor), hissing, striking, and biting.  The Eastern Hognose Snake (Heterdon platirhinos) will play dead, or will regurgitate its food.  It will also hiss like a cobra.  Hognose snakes also possess pseudo-fangs in the back of its mouth - which biologists speculate might be used to penetrate the paratoid gland of toads - their favorite prey animal.

Handling Amphibians
Wear gloves when handling amphibians to protect the animal from contact with contaminants that may be on your skin such as lotions and harsh detergents.  Choose a different spot each time to minimize habitat disturbance.

Amphibian Hibernation
Natural "cues" for dormancy for amphibians in Illinois include descending temperatures, amount of daylight, and a natural rhythm of some sort.  For tree frogs, the outer body actually freezes while the inner organs remain thawed.  This is possible via a natural chemical in their bodies that acts as an antifreeze.  Green Frogs and other true frogs will remain at the bottom of a pond in a state of dormancy and will absorb oxygen through their skin.  True frogs must remain in liquid water unlike their tree frog counterparts.  Salamanders must overwinter in the soil below the frost line.  Table 1 summarizes the different overwintering methods for the major groups of amphibians in Cook County.

  Table 1:  Amphibian Hibernation

Tree Frogs	True Frogs	Salamanders
Freeze	Remain in liquid water beneath ice	Below frost line in soil

Reptile Hibernation
Snakes gather in bundled masses in what is called a hibernaculum.  Sometimes snakes will leave scent trails so that other snakes can find the hibernaculum.  Hibernaculums can sometimes be multispecies.  Hibernaculums are usually located in burrows created by something else such as another animal species, under rock crevices, or in man-made structures.

Turtles will burrow into muddy embankments of ponds.  Hibernating turtles will actually breath through their butt!  Water is sucked in through their anal opening and oxygen is absorbed.  They can then exhale out the same anal opening.

Salamander Respiration
Salamanders, depending upon the species or life stage, can breath through their skin, lungs, or with gills.  The Mudpuppy is a fully aquatic salamander that never looses its gills.  In rare cases, salamander species that normally loose their gills and come out onto land will not do so for some reason.  This phenomena is known as neotinism.  There are no known reports of neotinism among salamanders in Illinois.  Neotinism is most commonly encountered in the Rocky Mountains where there is variable terrine.

All species of salamanders need to keep their skin moist, and they must breed in ephemeral (seasonal) wetlands.  

Environmental Sensitivity
Salamanders are good indicator species as a sudden decline in salamander populations could imply environmental stressors such as water pollution.

Salamanders in the Greater Chicago Region
Newts (Notophthalmus viridescens) are found in some areas of Cook County.  Newts have an unusual lifecycle with a second aquatic stage (figure 2).  Newts in their terrestrial stage are referred to as efts.
In Cook County, newts and mudpuppies can be found at Northerly Island and at Wolf Lake.

Figure 2:  Life cycle of newts

Tiger salamanders  (Ambystoma tigrinum) are a common species (see figure 3). Blue spotted salamanders (A. laterale) are also fairly common but are slightly less pollutant tolerant than tiger salamanders.  Redback salamanders (Plethedon cinereus) are rare.  Redback salamanders have an unusual defense mechanism where it can detach its tail, which will then wiggle around and confuse the predator  Redback salamanders can also regenerate other limbs.

Figure 3:  Tiger salamander

Hellbenders (Cryptobranchus allganiensis) is the largest salamander in the United States.  It is not related to the Mudpuppy.  There is one subspecies of the hellbender, known as the Ozark Hellbender, and its native range includes the very south part of Illinois.  Currently, healthy populations of Hellbenders remain in the Appalachian Mountains; elsewhere their populations are degraded.  Hellbenders eat crayfish, fish, and other stream animals.  Although they are an aquatic salamander, Hellbenders do in fact have lungs although they don't really have a need for the.  Hellbenders are closely related to the Chinese and Japanese Giant salamanders, (Andrias davidianus and A.  japonicus, respectively) and these two respective species have been hybridizing.

Salamander Conservation
Salamanders are needed for ecosystem balance.  Also, salamanders might be important subjects for medical research purposes.  Salamanders are indicator species which can be used to detect environmental change.  Salamanders are enjoyable to see, as well.  We can conserve salamander populations by protecting wetlands and preserving land.  We can learn more about them, and we should leave wild salamanders in their natural habitats and not take them in as pets.