Making Connections
Amphibians are tied to wetlands because of their mode of reproduction. And since chemicals can easily penetrate their moist skin, they are particularly sensitive to chemical pollution. When students near the Great Lakes discovered numerous frogs with deformed legs, researchers were prompted to study possible links between frog deformities and chemical pollution of the environment. Researchers have since determined that at least some of the deformities were caused by parasites that disrupt normal development of eggs into frogs. But just as canaries were once used to warn of the buildup of lethal gases in deep coal mines, amphibians may be warning us of a chemical buildup in our environment.

Background
Amphibians are characterized by moist glandular skin that dries out easily; therefore, they are generally intolerant of salt water. They live the first part of their lives in water and breathe with gills; they spend the second part of their lives on land and breathe with lungs. Because amphibians are unable to generate their own heat, they must hibernate during cold weather in the mud at the bottoms of wetlands or on land below the frost line. During the spring and summer period of courtship, male frogs call female frogs to come to the water for mating and egg laying. Each species has its own song, so this is one means of identifying frogs, even if they cannot be seen. After a mating ritual, the female lays her eggs in water, where they are fertilized by the male frog. The eggs develop in the water, then hatch into tadpoles that eat algae. The tadpoles then change (metamorphose) into adult frogs that eat insects.

Frogs, toads, and salamanders are all amphibians. They all lack claws, but there are some differences.

Reptiles found in wetlands include lizards, skinks, turtles, and snakes. The skin of reptiles is covered with protective scales and their toes have claws. Like amphibians, they have no internal way of regulating their body temperature, but they often warm themselves by sitting in the sunshine on rocks, stumps, or logs in or near water. Reptiles lay leathery eggs in holes that the female has dug on land; she then covers the eggs and leaves them. Often these nests are raided by predators, such as raccoons. If this happens, the remnants of the egg shells will be scattered around the nest site. If the reptiles hatch and leave the nest, the egg shells will stay buried in the ground and will not be visible. When reptiles hatch, they look like their parents, except that they are smaller and sometimes have protective coloration.

Procedure
Warm Up - Copy and cut out enough Frog Song Cards so that each person will receive a card. Mix the cards and distribute them to students. All cards are secret (do not show them to anyone) and no sounds are allowed except frog songs. At a given signal, male frogs should begin calling; females should listen to locate an appropriate partner. Depending on how clearly and loudly they call, some male frogs will have many partners, some will have none. Continue until all female frogs have found partners. Based on frog species, everyone has now been assigned to one of four groups for small group activities.

Activities
(All grades)
Select some or all of the following techniques to monitor herptile populations. Remember to log all herptile sightings and counts on the Records of Wetland Herptiles Student Page. Be sure to keep these records in a “Wetlands Log Book” for use in determining patterns of activity, habitat use, species diversity, and population sizes. These records will document long-term changes.

A. CASUAL OBSERVATIONS (Individual or small group)
The day after a rain, take a quiet walk around the wetland. Pause occasionally to look and listen. Record sightings of herptiles in individual nature journals or on data sheets. Be sure to indicate the date, time, weather, location, and species descriptions. Also record the activity in which the creature was engaged (egg laying, basking, swimming, mating, calling, running away). Summarize the information for class records.

B. FROG SONGS (Group activity)
Listen to a recording of frog songs (see Frogwatch USA under Resources) and/or have a naturalist teach some of the songs of local frogs. Once a month from February to September, go to the wetland and very quietly listen for frogs. Identify and record the names of as many species as possible. Frog songs may also be recorded in the wetland, then listened to in the classroom for identification.

C. EGG MASSES (Group activity)
Once a month from February to September, check for egg masses along the water’s edge. If an egg mass is found, gently scoop up some of the eggs with a fine mesh net or plastic container. Using a field guide and local species list, attempt to identify the species that produced the eggs. Try not to touch the eggs with your hands, since this may cause disease or injury. Gently return the eggs to the water where they were found in as short a time as possible. Mark the location of the egg cluster on a map of the wetland (along with the species name).

D. BASKING TURTLES (Individual or small group activity)
Turtles often bask in the sun at regular times each day, usually between 10:00 a.m. and 2:00 p.m. If an elevated area is available that allows a view of basking sites (such as a roof or a blind), then this technique can be used to determine the minimum population size and species diversity of turtles.

First determine which turtle species occur locally by checking with a nearby nature center. Then locate an observation post that allows a view of several basking sites, but is far enough away that turtles will not be frightened into the water. Binoculars or a spotting scope are helpful in identifying turtles at a distance. Make several counts during a thirty-minute interval. Record the date, time of day, weather, and number of each species seen basking. Repeat the observations on a weekly or monthly basis to improve accuracy of the counts.

E. TURTLE NEST COUNTS (Group activity)
During summer, female turtles briefly visit dry land to lay their eggs. Turtles select a suitable location for the nest, dig a hole, lay the eggs, then cover and camouflage the nest. Intact turtle nests are not likely to be located by humans unless a female is discovered while she is laying eggs. Turtle nests, however, are frequently preyed upon by raccoons, skunks, and opossums who dig up and eat the eggs. Eggshell fragments scattered about the nest site remain visible for several weeks. On a weekly or monthly basis, walk about the wetland looking for signs of turtle nests. Destroyed nests can be counted, their locations mapped, and possibly the species identified by looking carefully at the shell fragments. Collect the eggshell fragments to prevent counting the same eggshells again on a later survey.

F. ANNUAL CENSUS (Group activity)
In small groups, search assigned areas in and around a wetland during a single day in May or June when the herptiles are most active (the day after rain is best). Gently turn over logs (return them after looking!), rake through leaf litter, check stream beds and banks, and carefully check the water’s edge. Attempt to capture, identify, and measure all herptiles, then record their location on a map of the wetland area. Use small nets to capture the creatures. If handling the animals, make sure hands are first moistened with non-chlorinated water. If creatures are laying eggs, leave them alone! Attempt to identify them at a distance and record the nest location on the map. Once captured, the creatures may be placed in a small plastic carrying container so that they will not be accidentally crushed while they are being identified. Keep the creatures in the shade so they do not become overheated or dehydrated.

Length may be measured using a ruler. Measure from the tip of the snout (nose) to the tip of the tail for salamanders, skinks, lizards, and snakes. Measure from snout to vent (anus) in frogs and toads. Measure the length of the bottom of a turtle’s carapace (shell). To measure wriggling creatures, move them to a small plastic bag so they hold still, but be careful not to smother them! Return all creatures as soon as possible to the same place they were found.

Grades 9-12
The following technique can be very hazardous to herptiles and should not be attempted unless the traps will be faithfully monitored daily!

G. DRIFT FENCES AND PITFALL TRAPS (Individual or small group activity)
If a small group of reliable individuals plan to do a research project on herptiles, excellent directions for construction and use of drift fences and pitfall traps is included in Save Our Streams: Handbook for Wetlands Conservation and Sustainability, 1998. The Y-trap suggested is used in general surveys of herptiles. Wetland researchers tend to use a single drift fence with four pitfall traps, two on each side of the fence and two at each end of the fence, to derive information about breeding populations. If the fence is placed a short distance above a wetland area, herptiles can be intercepted going to and from the wetland, and their direction of travel can also be determined by the traps in which they are caught.

Wrap Up and Action
Look carefully at the data collected. Post it on the blackboard, a poster, or an overhead transparency. How many species of herptiles did you find? Which species was most abundant? Which was the rarest? How do these species use the wetland? At what time of day do they use it and for which activities? If this is a continuing activity, how have species diversity, population numbers, and use of the wetland by these creatures changed over time? Why?

Assessment
Based on the data collected, have students do the following:

Extensions
Continue monitoring the wetland creatures over time. Locate another wetland nearby and determine its similarities to and differences from the first wetland. Monitor the herptiles at the second wetland. Determine how the animal populations differ between the two wetlands.

Join the North American Amphibian Monitoring Program. You can enter your data on the Web site.

Resources
Brooks, R. P., D. A. Devlin, and J. Hassinger. 1993. Wetlands and Wildlife. Pennsylvania State University, University Park, PA.

Conant, R. 1975. A Field Guide to Reptiles and Amphibians. Houghton Mifflin Company, Boston, MA.

Firehock, K., L. Graff, J.V. Middleton, K.D. Starinchak, and C. Williams. 1998. Save Our Streams: Handbook for Wetlands Conservation and Sustainability. Izaak Walton League of America, Gaithersburg, MD.

Lingelbach, J. 1986. Hands-On Nature. Vermont Institute of Natural Science, Woodstock, VT.
National Wildlife Federation. 1998. Ranger Rick’s Nature Scope: Let’s Hear It for Herps! McGraw-Hill, New York, NY.

Smithberger, S. I. and C. W. Swarth. 1993. “Reptiles and Amphibians of the Jug Bay Wetlands Sanctuary,” The Maryland Naturalist. 37(3- 4):28-46.

White, C. P. 1989. Chesapeake Bay: A Field Guide. Tidewater Publishers, Centreville, MD.

Zim, H. S. and H. M. Smith. 1987. Reptiles and Amphibians. Golden Press, NY, NY.

Online resources:
A Thousand Friends of Frogs - activities, information, teacher resources

Frogwatch USA - locate tapes of frog calls, local species lists, frog identification, pictures, range

Frog Web - activities, monitoring programs, information

Journey North Program - range maps, call recordings, shared data on frogs

North American Amphibian Monitoring Program - frog call survey, salamander monitoring, teachers’ toolbox with experiments and data collection

Terrestrial Salamander Monitoring Program - salamander monitoring and experiments