The Ohio Frog and Toad Calling Survey





Call Route Selection

You may volunteer to monitor calling amphibians from your choice of Ohio counties. We will approve that county for you, based on the number of sites within that county that are already being monitored. You might be asked to monitor a neighboring county if yours is already sufficiently covered.

You will be assigned a township based on a random selection and asked if there is any reason that you are uncomfortable monitoring that township (i.e.. safety, it is engulfed by urban sprawl, etc.). If the township selected for you is unsuitable, a second random selection will be made. If the selected township is suitable, you will chart a route through the township marking the first ten potential amphibian breeding sites (flooded ditches, creeks, rivers and their backwaters, sloughs, farm ponds, ephemeral ponds, lakes, flooded fields, or wetlands [original or restored]) visible from the road.

The selection of routes and identification of all breeding sites should be done during the day, and less than one week prior to the first evening that you collect data.

Your route should start at an intersection that is easy to find, and your odometer must be set to zero miles. On a single map, highlight the route, and mark and number each of the ten potential breeding site. Exercise precision when making your map. The same route will be followed four times this and each year that the project remains intact. Your initial map is of utmost importance and cannot be changed.

The breeding sites that you select must be visible from the road. If a breeding site extends along a road for a considerable distance, position yourself near the highest chorusing activity and record data from that area. Do not include a pond, creek, etc. that you know is just beyond your view. This will insure that anyone running your route in the future will be able to sample the sites you have selected. Each breeding site must be at least one half
of a mile apart.

Safety Concerns

Please consider your own safety and the privacy of residents when selecting your sites and running your routes. Avoid getting out of your car or stopping it in traffic. Contact the home owner if one of your sites is near a house. If the home owner prefers that you not stop near their house at night, do not include that site on your route. However, many home owners may be pleased that a creek or pond in their yard is being included in the study. Exercise courtesy by informing them of the day and time that your route will be run. Rural households often have dogs. Do not stray far from the safety of your vehicle.

Breeding Site Selection

You must describe each breeding site (according to the blue paper entitled Index of Site Descriptive Terms included in your packet) and note the number of road miles (to the nearest tenth) that it occurs from mile zero. This index will be valuable to you if, for example, you are unsure of the difference between a slough and a river backwater. Use the green paper entitled Site Description Form in your packet to record this information. This will only need to be done once and that will be on your first trip when you determine your route and identify your potential breeding sites. The only time that a change will need to be made, is if the breeding site is destroyed or altered such that the description needs to be adjusted.

Three copies of the map, and the Site Description Form must be made. One will be yours, one will be sent to the project coordinators, and one will be sent to the Ohio Department of Natural Resources. Each of these maps and site description forms must be identical. If a camera is available, photographs of each breeding site may be valuable in the future. A labeled copy of each photo should be sent to the project coordinators with the rest of your data. If you take photographs (slides are preferable) of breeding sites, label the county, township, road, and the breeding site number that corresponds to the numbers on the Site Description Form. Also include the photographer's name, address, and telephone number.

Ohio Frog Breeding Seasons

Ohio frogs and toads, depending on the species, may begin chorusing as early as mid to late February and continue into August. One species, the spadefoot toad, has been known to chorus into August, but it is Ohio's rarest species, known only from four localities in southeast and south central Ohio. If at any time during the sampling season, you record spadefoot toads, you should contact the Program Coordinators immediately (do not wait until the next day - go to a phone booth and call as soon as your route is finished).

Four periods have been identified in which the breeding seasons of Ohio's frogs and toads overlap most frequently. Sampling during these times should yield the highest success. Although two species, spring peepers and wood frogs may be calling by early March, we suggest that the third week of March be set as the first sampling period. Both species may still be calling, and mountain chorus frogs, western chorus frogs, American toads, and leopard frogs can also be expected depending on your county's location.

The second sample should be taken during the third week of April. Of the aforementioned species, only wood frogs will have stopped chorusing. The others will continue and will be joined by pickerel frogs. In the southeast and south central portions of Ohio, after the heaviest thunderstorms, the most fortunate individuals may hear spadefoot toads.

Sample three will be taken during the third week of May. Many of the early spring breeders will have left breeding sites, making room for a new breeding assemblage. The calls of Fowler's toads, gray treefrogs, cricket frogs, and green frogs will dominate during this period. Two species of gray treefrogs, identical in appearance, occur in Ohio. They can only be distinguished from each other by the rate of their trill, or by examination of the size of their red blood cells. Trill rate (call rate) is affected by the temperature of their surroundings. It will be of paramount importance that accurate temperatures are recorded during the third sample. Weak batteries in tape recorders can affect the tape speed and alter the recording of the call rate. Tape recorders should have fresh batteries to insure that the tape speed is normal during the third sample. There is the remote chance that those of you in the appropriate regions of the state may hear spadefoot toads.

Five or six species can be expected to be calling during the third week of June. This is the period selected for the fourth sample. Fowler's toads will be nearing the end of their breeding season, but the others from the third sample will continue to call. Additionally, the bullfrog, Ohio's largest frog will join them. Again special considerations should be given to the spadefoot toad.


Materials: Thermometer
Standard size cassette recorder.
Blank cassette tape.
Fresh batteries.
Data sheets
Call Route Map
Writing Utensil


1. You will sample your route after having previously selected ten sites and marking them on your Call Route Map.
2. During the suggested sampling periods, visit each site at least one hour after sunset (the temperature needs to be above 50oF).
3. Before you start, you need to report the county, township, route number, date, starting time, the name of each member of your crew, and the weather conditions (air temperature, sky conditions, etc.) onto the beginning of your cassette.
3. Proceed to the first potential calling site that you marked on your map. Before you leave your car, announce the site number and time onto the cassette tape.
4. You will need to park and turn off the engine (ambient noises may cause frogs to stop chorusing). Situate yourselves as close to the breeding site as possible to insure the best recording results. Everyone in your group must remain silent and still until frogs adjust to your presence and begin chorusing again. Take the air temperature while waiting.
5. When frogs begin chorusing again, turn your recorder on and allow it to record for three minutes. Remain silent and still during this time. Each observer must estimate the relative abundance of each calling species by rating the density of individual calls according to the following scale.....
0 = no calls heard
1 = individual calls not overlapping (record the number of individuals calling)
2 = some overlapping calls, but the number of individuals calling can be reliably estimated (record the number of estimated individuals calling)
3 = a continuous chorus of calls in which individual calls could not be discerned
6. At the end of three minutes, announce the air temperature into the microphone and stop the tape.
7. If possible, record the water temperature and announce it into the microphone.
8. Complete all information on the data sheet before leaving the site.

When the sample is complete, all observers in the group should discuss the species they heard and the relative abundance of each. When the group
reaches a consensus, the data should be recorded on the data sheet.

9. Proceed to your next site and repeat steps three through eight.
10. At the end of your tenth site, record the finishing time onto the cassette tape.

Content on the Ohio Frog and Toad Webpage by Jeff Davis. Site design by Greg Lipps. *The Ohio Frog and Toad Calling Survey is supported by the Ohio Division of Wildlife with funds donated to the Wildlife Diversity and Endangered Species Program through the state income tax checkoff and revenues from the sale of wildlife conservation license plates. Thank you Ohio!