USGS

Wisconsin Frog and Toad Survey:

History and Data Collection

Information on the Wisconsin Frog and Toad Survey

The WFTS was initiated in 1981 by Ruth Hine of the Wisconsin Department of Natural Resources (WDNR), in response to concerns over what appeared to be declining populations of leopard frogs, pickerel frogs, cricket frogs, and possibly other anuran (frog and toad) species. This concern was not only for the species themselves but also for the ecosystems on which they depend. The purpose of the survey is to increase our knowledge of anuran distribution, abundance, status, and long-term population trends.

This auditory survey relies on the ability of volunteer observers to identify each of Wisconsin's 12 anuran species by their distinctive breeding calls. The methodology is based on the initial recommendations and audio instructional tape of Jansen and Anderson (1981). After 3 years of experimenting and gathering phenological data with the help and comments of several volunteers, Mossman and Hine (1984) standardized criteria and procedures for the survey. Cooperators were enlisted by word of mouth, notices in many newsletters and magazines, by making presentations at nature centers and meetings, and through contact with reliable observers from other cooperative programs such as the statewide black tern survey and natural areas breeding bird survey. In subsequent years cooperators were added from various sources, and beginning in 1992 WDNR Wildlife Managers routinely ran surveys or enlisted new cooperators. Initially, routes were established wherever cooperators were available, although poorly sampled areas of the state were increasingly targeted. In the early 1990s we set a goal of establishing at least 2 routes in each county. Our current goal is to stratify coverage geographically according to ecoregions and sections established by U.S. Forest Service (USFS).

The WFTS includes approximately 120 permanent roadside routes throughout the state. Each route consists of 10 listening stations selected subjectively by a volunteer observer to be within hearing distance of wetlands that represent the range of local anuran breeding habitats such as ephemeral ponds, lakes, meadows, marshes, and wooded swamps. Stations are located far enough apart that individual frogs cannot be heard from more than one station. Depending on local topography and vegetation, inter-station distances are as close as about 400m (1/4 mile), but were generally greater, usually on the order of 0.8-3km (1/2-2 miles). Routes are run after sunset under favorable conditions, i.e., relatively warm air temperature, wind <14 km/h(8 mph), and preferably humid. Most routes are 15-40km (10-25 miles) long and take 2-3 hr to complete. At each station the observer listens for 5 min (or up to 10 min if necessary due to noise interference) and records one of the following call index values for each species heard:

Because the annual calling period of each species is fairly short and is different from the calling periods of other species, cooperators attempt to run each route a total of 3 times every year, once each during the following sampling periods: Water temperatures are recorded where feasible, and where they appear to represent the conditions in which frogs are breeding. Air temperature, wind speed (beaufort scale), and sky condition are recorded at the beginning and end of each route. Cooperators are asked to comment on changes in wetland conditions, problems with background noise, etc., and are encouraged to take along at least one other reliable observer who can run the survey alone if the primary cooperator is unable to do so at some future time.

When a new route is established, we send the interested cooperator county maps of the area, indicating the locations of previously established routes to avoid overlap. We suggest that the cooperator run 11 or 12 stations during the first year, and then select as permanent stations the 10 with the least noise interference, access limitations, or other problems that might not have been apparent initially. The cooperator returns a county road map with the stations indicated, and we send them back photocopies of the appropriate 7.5' topographic maps on which to mark the exact locations. These are returned to us along with narrative and legal descriptions of each station location and a general description of nearby wetlands. We check these for accuracy and clarity, and make 3 clear sets of the route description, and of topographic and county maps with station locations marked on them. New cooperators are asked to purchase (at cost) a copy of Jansen and Anderson's instructional, audio cassette tape of anuran breeding calls from Madison Audubon Society. There are no formal training sessions. People interested in initiating a new route are usually asked to first go along on a previously established route with an experienced cooperator.

To help us determine the effects of air and water temperatures, wind, time, and date on anuran calling frequencies, some cooperators conduct 5-min counts at frequent (1-10 day) intervals throughout the spring and summer at a single station close to their home.

We use several techniques to measure the abundance and population trends for individual species. For more information, see: How population trends are estimated.

Information on the Wisconsin Frog and Toad Survey in Response to NAAMP Questionnaire.

In February 1998, North American Amphibian Monitoring Program (NAAMP) staff sent a questionnaire to all states and provinces with auditory anuran survey programs. Following are the questions and our responses for the Wisconsin Frog and Toad Survey (WFTS). For comparison, you can check the responses of other states by viewing their web pages, through the NAAMP home page (see: Links to other sites). The literature cited in our responses is listed in the bibliography.

Q: What is the history of amphibian monitoring and inventorying in your state?

A: These efforts have been reviewed in various publications, e.g., Vogt 1981, Casper 1996, 1998. The WFTS was initiated in 1981, and began statewide coverage on permanent routes in 1984. The program and its history are described by Mossman et al. (1998). Wisconsin also has a Natural Heritage Inventory program that maintains records for critical species such as four- toed salamander, the state-endangered Blanchard's cricket frog, and pickerel frog. The Wisconsin Herpetological Atlas project (Casper 1996, 1998) maintains documented recent and historical records of all amphibians in the state. Several projects have been undertaken to determine the status and distribution of individual amphibian species such as leopard frogs (Hine et al. 1981), pickerel frogs (Johnson 1984), and cricket frogs (Jung 1993, Hay 1998), or to inventory all amphibians or critical amphibian species in specific sites or areas (contact Bob Hay for more information on these). A bibliography of Wisconsin Herpetology is available (Dlutkowski et al. 1987, Watermolen 1992).

Q: Any comments on the first years of calling surveys?

A: These have been summarized by Mossman and Hine (1984, 1985) and Mossman et al. (1998). Our methodology was developed under the leadership of WDNR researcher Ruth Hine, with the recommendations of Debra Jansen and Ray Anderson (1981) of UW-Stevens Point. We spent 3 years (1981-83) testing methods, especially regarding the number of stations that could be surveyed realistically in a night, the ability of cooperators to use the call index, and fitting survey periods to species' calling phenologies. The WFTS was blessed with a source of capable and willing volunteers, through other volunteer programs such as statewide black tern survey, Scientific Areas bird survey, and the federal breeding bird survey. Others were enlisted through organizations such as the Wisconsin Society for Ornithology, Phenological Society, etc. We did not attempt to analyze population trends seriously until around 1989, because: we did not have good analytical support; so few years had been sampled; we were still adding many new routes; and we were too busy simply coordinating the survey. It was essential that we communicated regularly with individual cooperators, especially during the early years, in order to ensure that routes were run correctly, that we had accurate route maps and descriptions, continuity on routes, and that we could work out problems with protocols, survey instructions, etc. The results of a 1987 cooperator questionnaire were summarized by Mossman et al. (1998). After Ruth Hine retired in the mid 1980s, agency support for the WFTS declined, and every bit of available staff time and energy was used up in simply keeping the program running--consequently, reports to cooperators were not as frequent nor as good as they should have been and some cooperators left the program without being replaced. Coverage and reporting improved with the hiring of a staff herpetologist (Bob Hay) in 1990, and with dawning awareness of amphibian declines and increased agency support.

Q: What other kind of monitoring needs to be done in your state and why; and which amphibian species are well-covered by monitoring in your state?

A: We ran a power analysis on 1984-95 WFTS data, which indicated that our survey currently monitors the following 8 species well enough to detect a 3% annual decrease over a 20-yr period (at 75% power and p<0.1): wood frog, chorus frog, spring peeper, northern leopard frog, American toad, Cope's gray treefrog, eastern gray treefrog, green frog. By this definition our survey is not adequate to detect this level of change in the remaining 4 species (pickerel frog, Blanchard's cricket frog, mink frog, bullfrog), although the data could detect longer-term trends, those more extreme than 3%/year, or perhaps in areas of the state where trends are especially strong. The species in most need of additional monitoring are cricket frog (which has almost disappeared from the state), and pickerel frog (uncommon to rare in the state, but with declines strongly suggested by the WFTS). Cricket frogs--common throughout southern Wisconsin as recently as the 1960s--are now so rare that studies here are probably meaningful only as part of larger investigations that include nearby states in which the species is still common enough to study. No salamander species are adequately monitored in Wisconsin, although some work is done locally; species for which inventory and monitoring data are most needed include four-toed salamander, mudpuppy, and perhaps central newt.

Q: Do you know about our new terrestrial salamander monitoring program?

A: Yes. Because we are now involved so heavily in auditory counts and other amphibian studies, we will probably wait to decide on developing a terrestrial salamander monitoring program until we see more results from programs elsewhere.

Q: Do you keep us regularly updated on all your materials?

A: We have added NAAMP to our cooperator mailing list so that you receive all materials annually; you can also keep up with our program on our web page.

Q: Have you modified the protocol for your region? If so, how?

A: Beginning in 1991, we expanded our early spring survey period, because observers had been noting that the period was too late to sample wood frogs during years in which spring arrived especially early. Formerly it began on 15 April, and now it begins on 8 April. We have about 120 permanent roadside routes, most of which have been run for several years, and a few of which have been run annually since 1981. These routes were chosen subjectively by cooperators to represent the range of amphibian breeding habitats in their area. In 1997 and again in 1998, we ran an additional 80 routes selected by NAAMP "stratified-random" protocols, in order to test for differences between data collected on these routes and traditional routes. Of the new routes, 40 have stations placed at half-mile intervals along randomly selected routes, regardless of proximity to wetlands; and the other 40 routes are placed along randomly selected routes at sites at least a half mile apart but within 200m of wetlands judged by the cooperator to be potential breeding habitat. On these new 80 routes we also collect data during 3-min intervals (NAAMP protocol) and 5-min intervals (WFTS protocol), so that we can compare the results. It is uncertain whether we will run these new routes beyond 1998 at this time. These data are now being analyzed.

Q: What sort of quality assurance checks do you do each season?

A: We provide detailed instructional materials and cooperators buy our instructional cassette tapes at cost (through Madison Audubon Society). We do not have training sessions, although we would like to. For the sake of continuity we strongly encourage observers to go along on established routes with an experienced observer before setting up and running a new route; we also encourage observers to run their route with at least one other person who can take over the route alone if necessary, in case the primary observer cannot, temporarily or permanently. We communicate with cooperators regularly by mail, email, and telephone, regarding problems we note or suspect from their data returns, or to answer their comments or questions. Considerable time is spent in these sorts of communications, and with ensuring that route maps and directions are clear, accurate, and precise.

Q: What sort of attrition rate do you have for routes?

A: This rate is fairly low now, although it was higher during the early years when we were anxious to get new routes established. Of our 120 traditional routes, about 100 get run annually. About 20 additional routes have been abandoned, mainly during the first 5 years, because of cooperator attrition. Every newly established route takes considerable time for the observer and central staff to determine an appropriate route location, and to develop standard, clear, accurate directions and maps; so we are careful to ensure that new routes are likely to be continued before we encourage their establishment. In general, we opt for continuous, consistent, well-documented coverage, rather than coverage that is more extensive but perhaps irregular or careless. We have found that we can minimize attrition in the following ways: 1) Always ask interested new observers to go along on another route for a year before establishing a new route; 2) Encourage new, interested people to be an alternate observer for an established route or to take over an abandoned route in their area (if these are needed), rather than establish a new route; 3) Encourage local people to establish or run routes rather than people who live far from the route, when possible; 4) Discourage people from being responsible for more than one route, until they have run a route for a few years and understand the amount of time necessary to run it well; 5) Communicate regularly with cooperators who need it, and demand rigorous attention to protocol and documentation while encouraging them to enjoy the experience and letting them know how valuable their contributions are; 6) Provide feedback in the form of reports, informative annual letters, and presentations at nature centers, schools, professional meetings, etc.

Q: What percentage of volunteers complete all the runs and send in their data every year?

A: We haven't calculated these percentages. Probably about 75% complete all 3 survey runs in a given year, which we find acceptable. Probably about 90% of observers send in their data each year, although it sometimes takes as many as 3 reminders.

Q: What kind of data analysis do you do? Do we have all your raw data?

A: Our analytical methods and results are described by Mossman et al. (1998) and on our web page. Techniques were developed with USGS biologists and statisticians, and most are based on techniques developed by some of the same people for the federal Breeding Bird Survey. In short, we analyze trends using several methods, using presence/absence of species at stations as well as by giving arbitrary weights to the 3 call index values; in most analyses we use "estimating equations" and route regressions, by which we calculate trends for individual routes and then weight these according to such criteria as abundance of the particular species on that route, the precision of the estimated trend on that route, and the geographic area that the route represents. For looking at relative abundance across the state, we summarize data by 7 ecoregions, mostly in terms of the percentage of all stations at which a species is recorded. NAAMP has our entire data set.

Q: Are volunteers taking consistent notes on habitat at route stops?

A: No, although some do. Our instructions ask for this in a general way, but we have not provided any specific guidelines, nor have we looked closely yet at observers' habitat notes to assess their usefulness. We have not suggested taking photographs.

Q: Do you record nighttime bird calls?

A: We did this for 1-2 years and thought it had promise. One year we provided volunteers with cassette tapes of the state-endangered barn owl, to play and record responses, but found that this was an unfair request for spending additional time on a route with very little chance for acquiring any barn owl records. On our new 80 routes (using NAAMP protocols) begun in 1997, we are requiring cooperators to record several night-calling birds (e.g., whip-poor- will, nighthawk, snipe; with other species optional); we are currently summarizing these data.

Q: What advice or insight would you offer to other coordinators, new and/or old?

A: Some of this we have given in our responses to the above questions. In general, don't expect the survey to run itself. Give time and care to cooperators and their data and route descriptions (e.g., ensure that they are sufficient to enable an observer inexperienced with the route to run it, even in the distant future, with nothing but the description and map provided). Provide good feedback to cooperators. Don't put too much faith in population trends calculated on only a few years' data: the results seem to change annually until enough routes and years have accumulated, and cooperators, resource managers, and the public will tend to lose faith in the survey when this happens; instead, for the first 5-8 years concentrate on results that give you new information on distribution and status, phenology, and also emphasize the educational and esthetic benefits that the survey is providing. Try your best to coordinate with adjoining states and provinces, and with the NAAMP, because the value of your data will be increased to the extent that you can compare your trends with those of other areas; furthermore, it will allow you to increase the value of your data by combining it into a larger dataset; for example, if you don't have a sample that is large enough to adequately track a particular species in your state or province, then adding your data into a regional database can at least help provide good trend estimates for the region you are a part of. At the same time, be skeptical of methodologies and always ask how they can be improved, especially now during the first years of the NAAMP program--better to hone the protocols now than try to do so later (e.g., after 19 years, as we're now considering in Wisconsin!). Take advantage of the fact that one of the most important results of this program is educational: turning people on to wetlands, nocturnal creatures, and habitat changes.

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