Minnesota Frog and Toad Calling Survey 2001

Congratulations Volunteers!!
The NAAMP's Frog and Toad Calling Surveys are highlighted in this year's State of the World 2001
book, a yearly report submitted by the Worldwatch Institute's research team.
Minnesota is exemplified in particular for its "well-tuned" volunteers.

Would you like to get involved in surveying frogs and toads in Minnesota? Scientists and herpetologists would like to get a more precise idea of the numbers of each frog and toad species in the state. This will enable them to look at population densities over time and determine whether populations of specific species are declining or increasing on a local and state-wide basis.

Background and Purpose:
In recent years, many observers have been concerned not only with the decline of global amphibian populations, but also with changes in frog and toad populations around the United States. Scientists worldwide are concerned about these declines because amphibians are shown to act as bio-indicators of environmental health. In 1991, scientists from every continent volunteered to be part of the Declining Amphibian Populations Task Force (DAPTF). "Established in 1991, the DAPTF consists of a network of over 3,000 scientists and conservationists belonging to national and regional working groups which now cover more than 90 countries around the world. The purpose of the DAPTF is to determine the nature, extent and causes of declines of amphibians throughout the world, and to promote means by which declines can be halted or reversed" (http://www.im.nbs.gov/amphibs.html).

The North American Amphibian Monitoring Program (NAAMP), the North American component of DAPTF, developed a set of standards to help monitor amphibian populations around the United States. The standards were further developed into monitoring programs, including the frog and toad calling survey. The NAAMP frog calling survey is an international effort to track the health of frog populations in Canada, the United States, and hopefully soon in Mexico. For more information on the NAAMP, please visit their web site at: http://www.im.nbs.gov/amphibs.html

The Minnesota Frog and Toad Calling Survey was initiated to increase the knowledge of the abundance and distribution of the fourteen frog and toad species, and to monitor population changes in the state. The NAAMP has developed a series of pre-established routes that include a variety of habitats, such as wetlands, forests and grasslands. Each route consists of ten wetland (breeding) sites, which are visited three times annually (early spring, late spring, and summer) by volunteer observers. At each site, the observer identifies the species present on the basis of breeding season calls and makes a simple estimate of the abundance of each species using "call index" values of 1, 2, or 3.

Establishing a New Survey Route
When you receive a new route that has never been surveyed, it must be tested before the first survey is made. First, locate the route on a map (shown below) and drive to its starting point. As you drive along the route look around for potential amphibian breeding sites. The sites should be no more than 200 meters off-road and may include areas such as ponds, shallow wetlands, streams, and roadside ditches. Try to include a variety of wetland types that represent the range of breeding sites available for the various species in the area. Consider large and small ponds; open, shrubby and wooded areas; stagnant and flowing streams; and agricultural and urban sites. Do not avoid ponds that dry up during the year, for they are often productive during the spring. Do avoid swift moving streams, and deep or denuded shores of lakes. Designate ten sites that are located at least 0.5 miles from each other. The ten sites become permanent stops on the route and will be used in each of the three survey runs.

Click on map to see larger version.

Surveyors sometimes find that one or more of the sites originally chosen turn out to be unsuitable breeding habitat, or are poor sites because of unforeseen background noise, access problems, etc. In these cases, it is necessary to replace the problem site with a new site sometime after the first survey run. To avoid this, it is recommended that you begin with eleven or twelve sites for the first year and choose the ten most reliable sites for the permanent route. At the end of the first year, report results only for the ten permanent sites.

If you come to the end of your route without placing all ten stops, then simply continue driving in the direction indicated until all ten have been determined. While busy looking for sites, it is also important to make sure that the roads are appropriate for stopping along. If they are too busy, too dangerous, on private land, or poorly maintained, the routes may be shifted to the nearest set of appropriate roads that travel in the same direction. Please make note of any changes or discrepancies on the maps and datasheets provided.

Describe your route. Mark the precise locations of your ten sites on the assigned maps, and describe each listening point and wetland on the "survey route description" form. Sites should be numbered in a convenient route sequence.

Enlist one or more additional observers who will become familiar with the route and survey procedures, and who can run the route in the event that you are temporarily or permanently unable to do so.

1. Obtain and review instructional materials and data forms.
The main, designated surveyor for each route should automatically receive these materials in late March or early April. Contact the coordinator if you have not received your packet by April 7th.

Materials include:
Instruction package, Sample form package, Route maps, Survey route description form, Field data sheet, Dashboard card, 'Toads and Frogs of MN and Their Habitats' poster, 'Call of Minnesota's Frogs and Toads' cassette tape (given to new surveyors).

2. Know the calls, phenology, and general ranges of Minnesota frogs and toads.
New and experienced observers will find it helpful to review the 'Calls of Minnesota's Frogs and Toads' cassette tape periodically, and to take it along during surveys to help identify uncertain calls. New observers can learn the calls gradually by starting with those species that may be calling during the early spring survey period (Wood Frog, Spring Peeper, Northern Leopard Frog, Western Chorus Frog, and Pickerel Frog) followed by those species that begin calling in late spring (the three toads, Northern Cricket Frogs and both treefrogs), and finally by those species that begin to call during the summer (Mink Frog, Green Frog, and Bullfrog). It is highly recommended that new observers practice distinguishing calls in the field with the help of a more experienced observer. Generalized species distribution maps are attached. Additional information on frog and toad natural history is available in Amphibians and Reptiles Native to Minnesota by Oldfield and Moriarty. This book should be available at your local library or call 651-523-2945 for more information.

3. Run the route 3 times, once during each designated period.
The timing of the survey with the phenology of frog calling is essential. Data collected from outside the designated survey periods is difficult to interpret and impossible to compare between years or areas. In most areas, failing to make one of the three survey runs or failing to survey all ten sites will severely limit or invalidate the entire year's data. In addition, consider minimum water temperatures, especially for the early spring survey period. The dates of the first survey run may be variable due to the differences in snowmelt in northern and southern Minnesota.

Survey Period Range of Dates Minimum water temperature
Early Spring April 15-30 50F (10C)
Late Spring May 20-June 5 60F (16C)
Summer June 25-July 10 70F (21C)

*Routes north of Highway 2 can add one week to the survey dates.

4. Run surveys after dark, under favorable conditions.
Choose an evening when water temperatures are above the minimums statewide and when wind is less than 8 mph. Warm, cloudy evenings with little or no wind and high humidity (even drizzly) are ideal. Humidity and cloud cover are not critical, but temperature is; a sudden drop in air temperature will cause most anurans to cease calling. If part way through a survey run you find that conditions deteriorate significantly (e.g., rain begins, temperature drops, or wind increases), stop the survey and complete it at the soonest opportunity (within 2?3 days if possible). Please make note of these conditions.

5. Listen for calls at each site.
Approach a listening point so as to cause minimal disturbance. The arrival of a car or a person on foot may cause frogs to stop calling for a short time. When the frogs start calling again, listen for five minutes. Listen to all calls audible from your listening point, not just those emanating from a particular pond or side of the road. Some calls may be drowned out by other calls, especially by the full chorus of Spring Peepers or Chorus Frogs. Where you suspect this to be the case, and after carefully listening and recording your initial data, you may try to silence the chorus by making a loud noise with the car horn, door or by voice. Listen for the less conspicuous species as the calling gradually resumes.

A tape recorder will enable you to record questionable situations that can be listened to and confirmed at a later time or date. A sound parabola is helpful in isolating subtle calls of individuals in a chorus of several species. Prescription hearing aids are helpful for listeners who have volume or frequency impairment.

6. Record your observations on the field data sheet.
Completely fill out the Minnesota Frog and Toad Survey route data sheet including county, route number, date, observers names and addresses, weather conditions, water temperature (if taken), time, changes in habitat since previous visits, and additional comments on noise levels, such as attempts to silence loud choruses. Record the call index value for each species heard according to the following:

1: Individuals can be counted with space between calls,
2: Calls of individuals can be distinguished but there is some overlapping of calls, or
3: Full chorus. Calls are constant, continuous, and overlapping.

7. Verify records of rare or extralimital occurrences.
Verification is required for Cricket Frogs and for records of other species found outside their previously documented range as indicated by the attached range maps. Verification can be accomplished by: a) a tape recording, b) testimony of two experienced observers, c) a photo, or d) a specimen. After an observer has verified the record, future records of the particular species in that area may not be required.

8. Return all materials by 1 September MNDNR Nongame Research.

9. Important! Maintain one or more alternate observers whom you feel will be able to produce results comparable to yours should you not be able to run the survey temporarily or permanently. The alternates should accompany you on the survey periodically and be familiar with the calls, route, and procedure.

For more information on Minnesota Frogs and Toads click here.
An audio-tape or CD of Minnesota Frogs and Toads Calls is available from the project at a cost of $12, which covers tax, shipping and handing. If you are interested in this tape, please send a check to Hamline University CGEE, MS-A1760, 1536 Hewitt Ave., St. Paul, MN 55104-1284. Make the check payable to Hamline University.

Barney Oldfield and John J. Moriarty produced a book entitled Amphibians and Reptiles Native to Minnesota (1994), which is available from the project. This excellent guide to the state's herps is invaluable to anyone interested in this topic and these animals.

This web site had been made possible by the generous support of various federal and state agencies, as well as private foundations and donation. Click here to see a list of the organizations whose donations have made this web site possible.

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