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   Amphibian Biomonitoring Creating the Context: Research Methodology     
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 the Context

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  Background Info
  Research Methodology
  Data Submission
  Results of Study
  Data Analysis
  Further Research


  Research Question
  Background Info
  Research Methodology
  Data Submission
  Results of Study
  Data Analysis
  Further Research
  Research Values



Training in Identification
It is very important that data collectors be familiar with the calls of local frogs and toads. Calls that are available on this website and commercially available tapes should be used to teach data collectors what calls to listen for. Information necessary for local anurans should include the range for each species as well as basic information on their natural history. Successful completion of a listening test given to each data collector to verify the observer's abilities should occur before going into the field.

Sampling Area Selection
It is best to scout the sample area during or just prior to the breeding season to determine the characteristics of the area. Many wetland areas that provide habitat for the amphibians can dry up during the summer. Identification of potential wetland sites should be done during the day and should not take into account the presence or absence of amphibians during that time. The best approach would be to have a separate group establishing the points from those going out and collecting the call data.

We recommend that a stratified, randomized method be employed to determine sampling locations. Differentiate between a large "area" of similar habitat (e.g., a large bog several hectares in size) and a large area with several discrete but similar habitat types or "basins" (e.g., many farm dugouts - water-filled pits used as watering holes - across a large agricultural landscape) that are to be surveyed. To better sample rare or highly specialized anurans in some regions, further stratification beyond a general approach to placing points at wetlands may be needed. The easiest way to accomplish this would be to identify section roads. Section roads are the roads that occur every mile and were (are) laid out in a grid. Stopping every .5 mile along this road would be a good sampling technique. Recorded with a directional microphone and a tape recorder all calling species at each stopping point. Each data collecting group should follow a different road.

Wetland breeding sites for amphibians come and go. It is to be expected that some sites will be better over time (for example, beaver activity may form a new pond), and others will disappear (for example, under a new shopping center parking lot). The stops should not be changed to incorporate new sites or eliminate sites that are no longer available. This is important because even if the main wetland is destroyed, other water sources, such as water control pits and drainage ponds, may still provide suitable frog habitat. Under unusual circumstances it may be possible that new forms of wetland may be developed where none formerly existed. If these new wetlands occur in places that were not initially determined to be within the realm of possible wetland locations (for example, the creation of new cattle tanks in upland areas that previously did not support anuran populations), then it should not be incorporated until the survey has been statistically adjusted to account for this new habitat. A review of wetland trends every 5 years should catch any such changes.

Data Gathering and Timing:
It is recommend that a driving route should require no more than one to two hours of observer time to complete, including commute time to prevent volunteers from becoming bored and no longer participating. Counts should begin one-half hour after sunset, approximately when birds stop calling. Driving surveys should be conducted on public, all-weather, all-season roads only. Each unique call should be recorded and the number of each calling frog or toad should be recorded. Make sure to identify which call goes with each number of calling species.

The number of detection's of new species rapidly falls off after the first minute of listening time (Shirose et al. 1995). Time for an individual survey stop along a route has been set at three minutes. Observers can listen for up to two minutes longer than the initial three minutes if noise from traffic, etc., is interfering with the ability to hear calls. We also advise volunteers to wait (quietly) one minute after arriving at the point and then begin the three-minute survey. This will reduce the effect any disturbance made by the volunteers' approach may have had on anuran calling.

The frequency of surveys must be tailored to capture the seasonal differences in calling rates of anurans in the observers particular region. Some rare species, species that call very late in the evening, species that call underwater, or species that don't call at all would not be expected to be adequately monitored in an extensive survey conducted within two hours after sunset. Driving surveys should be conducted at a minimum of once every two weeks during the breeding season. These should be begin in February and continue to June 1.

The current approach is:

  1. A random starting point and direction would be assigned and for practical purposes, these could monitoring points along the road (where it is safe) that are at least 0.5 miles apart.
  2. Wetlands along the roadside segment would be identified without prior knowledge of their capacity as amphibian breeding sites.
  3. A volunteer or technician would drive or walk the route listening at the identified monitoring points that were identified in (2). Any and all calls heard should be recorded with a directional microphone and a standard tape recorder. Each recorded call should be related to a specific monitoring point.
  4. Stopping points must be a minimum of 0.5 miles apart on both driving and walking surveys. The 0.5 miles distance corresponds to the minimum distance at which an observer is no longer able to hear calling frogs.
  5. Record the call of each unique calling species on a tape recorder. Record the number of anurans of each type calling at each stopping point.

Required Data:
The monitoring points must be marked and described by the observer and maps kept on permanent file at each participating school/agency. The latitude and longitude for each monitoring point needs to be determined. This can be done from a standard topographic map or GPS units may be borrowed from KanCRN to determine the Latitude and Longitude of each data point. Data collectors must record the latitude and longitude coordinates including topographic map number for each monitoring point, provide a verbal description of the location using semi-permanent landmarks such as bridges, curves in the road, geographic features, barns, houses, etc. (so that someone can get to within 10 meters of the site).
These points must be:

  1. recognizable by volunteers
  2. have an accurate latitude and longitude
  3. as permanent as possible
  4. known to the observer/ program coordinator
  5. identifiable on a topographic map.

On each survey, the observer must record:

  1. Observers name and school/agency.
  2. Time of day with start and finish time, and exact time the observations were made at each point
  3. Date of survey with the month spelled out and the year indicated.
  4. A recording of each call and the number of individuals of each type that were calling at that stopping point.

Habitat Data should include:

  1. A general description of the wetland /habitat type, e.g., vernal pool, pond in wood lot, marsh, bog, fen, creek, slough, farm dugout.
  2. A general evaluation of water level in the wetland at the time of the survey (if possible).
  3. Any major changes to the habitat type since the previous survey (optional).
  4. Any major changes to the habitats adjacent to the monitoring point habitat since the previous survey.

Data to be kept as Local Data may include:
Weather Conditions data recorded during each survey:

  1. Wind speed (Beaufort scale or exact speed if available)
  2. Air temperature to be taken at the start and end of the survey-- water temperature is optional (we recognize that on some types of surveys water temperature is not easily or consistently sampled and several procedures are under consideration).
  3. Percent cloud cover (start and end, per stop). Can later be translated to a numerical, Weather bureau sky code.
  4. Precipitation conditions (e.g., drizzle, fog, rain, downpour) ( start and end,per stop) Can later be translated to a numerical, Weather bureau sky code..
  5. Barometric pressure-- optional.
  6. Any noise which interfered with hearing calls (per stop).

Sample Analysis for Species Richness and Diversity

The following examples will guide your work in calculating Species Richness and Diversity.

Sample Data

    Blanchards Cricket Frog - 15

    Gray Treefrog- 5

    American Toad - 8

    Northern Spring Peeper -3

    Southern Leopard Frog - 6

Mean = (15 + 5 + 8 + 3 + 6)/5 = 7.4

Species Richness = total number of species found = 5

Calculating Diversity using the Simpson Diversity Index

Calculate the proportion of the total number of amphibians of each species (Pi).
Proportion species A (Pa) = number of species (A/Total) number of amphibians
Proportion species B(Pb) = number of species (B/Total) number of amphibians

To calculate the Simpson Diversity Index = 1 - sum(Pi)2
(meaning add the proportion of each squared species and take it from 1)

Using the example above, you have 15 cricket frogs, 5 gray treefrogs, 8 american toads, 3 spring peepers, and 6 leopard frogs. You would calculate:

Diversity Index = 1- ((15/37)2 + (5/37)2 + (8/37)2 + (3/37)2 + (6/37)2)
Diversity Index = .74

This index ranges from zero to one and is literally a measure of the probability that two amphibians taken at random from the sample are different species. A number close to zero means low diversity and it is likely you will get the same species of amphibian and a number close to one means high diversity.

  1999, KanCRN Collaborative Research Network