Authors:
Robin E. Jung, USGS Patuxent Wildlife Research Center, 12100 Beech Forest Rd., Laurel, MD 20708, robin_jung@usgs.gov
Isaac Chellman, USGS Patuxent Wildlife Research Center, 12100 Beech Forest Rd., Laurel, MD 20708, ichellman@usgs.gov

Species list
Description of technique
       Field time components
       Office time
       Equipment
Things that could bias your counts
       Species misidentification
       Weather
       Time of year/time of day
       Observer effects
Advantages and disadvantages
Approaches to analyzing your data
Existing protocols and programs using this technique
Estimates of variation of counts for this technique
Studies that have used this technique
Literature cited
Send a comment on this technique (this takes you to another page)
See existing comments (this takes you to another page)

Note: The species in the list below include only those species reported in scientific journal articles that were encountered in stream quadrats. Those species with asterisks indicate terrestrial breeding salamanders that have also been found using stream quadrats. These species should not be considered the only amphibians that could be encountered in stream quadrats. For more detailed species lists, consult Crother et al. (2000), Petranka (1998), Conant and Collins (1998), and Stebbins (1998). Crother et al. (2000) is published by the Society for the Study of Amphibians and Reptiles and contains the most up-to-date taxonomic classifications used in our list below.

Eastern United States:

Desmognathus fuscus, Northern Dusky Salamander; Desmognathus monticola, Seal Salamander; Desmognathus ochrophaeus, Allegheny Mountain Dusky Salamander; Desmognathus quadramaculatus, Black-bellied Salamander; Plethodon cinereus, Red-backed Salamander*; Plethodon cylindraceus, White-spotted Slimy Salamander*; Gyrinophilus p. porphyriticus, Northern Spring Salamander; Pseudotriton r. ruber, Northern Red Salamander; Eurycea bislineata, Northern Two-lined Salamander; Eurycea l. longicauda, Long-tailed Salamander; Eurycea wilderae, Blue Ridge Two-lined Salamander

Western United States:

Dicamptodon tenebrosus, Coastal Giant Salamander

The quadrat technique is a common sampling method for amphibians in terrestrial or aquatic habitats (Jaeger and Inger 1994). When used to survey stream amphibians, quadrats are small square areas of variable size set up in the stream channel, on the stream bank, or both (Table 1). We do not include Plots in our discussion here, which we define as areas of variable length and width (not square) that are typically less intensively searched. As a sampling method, quadrats can be used on their own, but they are often used in combination with other survey methods (e.g. stream transects). In some cases, quadrats are conducted every so many meters along stream transects (e.g., every 5 m along 100 m transects) (Mitchell 1998a,b, 1999, Jung et al. 2000, Cook et al., in prep.). A visual encounter survey technique is typically employed, in which the observer looks for amphibians on the surface and under rocks, logs, and other debris within the quadrat. Cover objects turned over to look for amphibians can be tallied with clicker counters to provide a catch per cover object measure of salamander abundance. Quadrat methods in streams often involve removing all cover objects (rocks, logs, debris) within the quadrat and raking through the quadrat, completely surveying the upper substrate layer and counting all salamanders (Mitchell 1999, Jung et al. 2000, Rocco and Brooks 2000). This is a fairly destructive method, but is effective in completely sampling the area and potentially obtaining a complete census of salamanders in the quadrat at the time. To minimize the overall disturbance to the habitat, all cover objects should be returned to their original positions once sampling is completed. In some cases, artificial quadrats have been created with a set number of cover objects within quadrats to determine relationships between cover object density and salamander density (Davic 1983, Davic and Orr 1987). Procedures used to catch salamanders in quadrat surveys are the same as those described in the stream transect writeup.

• Travel to and from the stream site
• Determining quadrat locations and laying out quadrat dimensions (variable amount of time)
• Habitat, location, and additional information (approximately 10 minutes)
• Collection of salamanders (15 minutes to several hours, depending on size of quadrat, search technique used, and numbers of salamanders encountered)
• Recording data on salamanders (5 minutes to 1 hour, depending on number caught, marking techniques used, and measurements taken)
• Replacing cover objects (10 minutes maximum)
• Returning salamanders to their original location [if collecting them] (10 minutes)

• Data entry
• Cross checking data for errors (proofing data)
• Statistical analysis
• Report writing

• Hard copy of protocol
• Data sheets for each stream
• Field clipboard
• Rulers
• Resealable plastic bags
• Clicker counters
• Pencil or indelible ink
• Thermometer
• Watch
• Meter stick or PVC pipe (for laying out quadrat dimensions)
• Meter tape (for large quadrats)
• Flagging (if you wish to mark the exact locations in which salamanders were located)
• Rubber boots or waders
• Fine aquarium mesh nets
• Water quality equipment (if measuring those variables)
• GPS Unit
• Camera
• Field guides for proper identification of larval and adult salamanders (e.g., Pfingsten and Downs 1989, Mitchell 1998a,b, 2000, Petranka 1998).

Things that could bias your counts

Species misidentification could be another source of bias in stream transects and any other survey involving amphibians. One person may identify a salamander differently than another individual. Species misidentification primarily occurs with certain larval salamanders. To avoid this problem, observers should be trained on species identification prior to collecting data and accurate species identification keys should be taken into the field for consultation. If necessary, large larvae should be raised through metamorphosis and the juveniles used to verify larval identification (Petranka 1998). However, it should be noted that there are times when experts have difficulty identifying larval salamanders. Geographic locality should be strongly factored into species identification (based on accurate distribution maps), because this will narrow down the pool of species known to occur in an area.

(above is from Species misidentification section of Stream Transects technique)

If species are captured during quadrat surveys (individuals can easily escape), species misidentification is reduced substantially. Individuals can be photographed or collected if necessary to document and validate the species identification.

Rising temperatures and rainfall are known to initiate breeding activities in many amphibians (Stebbins and Cohen 1995). Heavy rains early in the breeding season result in the congregation of large breeding groups of many salamander species (Petranka 1998). Surveys conducted during ideal weather conditions for peak salamander activity will provide highest salamander counts and estimates.

(above is from Weather section of Stream Transects technique)

If data are collected at the right time of year but under different weather conditions each year, counts may be quite variable and could potentially bias population trends. Hence, program managers need to standardize weather conditions under which surveys are conducted to reduce the impacts of bias. Unfortunately, ideal or standardized weather conditions under which to conduct surveys are not available in the literature.

Time of year:

Streamside salamander species differ in their courtship and breeding seasons, length of larval periods, and time spent within the stream versus surrounding terrestrial areas. According to Pauley (pers. comm.), June and October in West Virginia are the best months to survey for streamside salamanders, as these are the months when the greatest numbers of species are present at streams (see Leaf Litter Bag section). Bury and Corn (1991) suggest the optimum time of year for stream surveys to be June and July in California and the Oregon Coast Range, and June through August may be ideal for the Cascade Range of Oregon and Washington. Ashton and Ashton (1978) found that Eurycea bislineata tend to congregate in "winter retreats." They found temperatures in these retreats (areas where warm groundwater springs enter the stream) to be 1 to 4°C warmer than the surrounding stream. The last salamanders entered these winter refugia when stream temperatures reached 7°C. Their study suggests that Eurycea bislineata would probably be unevenly distributed in streams during the winter months. Optimal times of year to survey for streamside salamanders will vary depending on target species and geographical location. Consult scientific literature relevant to the species you want to sample in determining ideal times of year to conduct transect surveys (Petranka 1998).

Time of day:

Streamside salamanders are more active at night, when they come to the surface to forage for invertebrates, defend territories, and seek mates (Petranka 1998). In a study in Giles County, Virginia, Keen (1982) found that Desmognathus monticola and Desmognathus fuscus in field enclosures showed the highest levels of activity in the evening between 20:00 and 0:00, a lull in activity between 0:00 and 02:00, and a resurgence of activity between 03:00 and 06:00. In North Carolina, Hairston (1986) determined that night searches captured 1.65, 1.81, and 3.75 times more D. ochrophaeus, D. monticola, and D. quadramaculatus, respectively, than during the day.

(above is from Time of year/time of day section of Stream Transects technique)

If the study is concerned with a certain species, it is important to conduct the quadrat surveys at the time of year, time of day, or under weather conditions that are most appropriate and favorable for that species (Jaeger and Inger 1994).

Observer bias could be a possible factor when sampling stream transects. The ability to see or spot salamanders (search image) varies among observers, particularly in the case of very small larval salamanders (e.g., young larval Eurycea). The largest bias comes from the ability of observers to catch salamanders. Some people are better at capturing salamanders than others, so capture results will often depend on the individuals involved in the study. If a person is not very good at catching salamanders, there will be more escapes, leading to higher inaccuracy in population estimates and assessing species presence. The physical strength of observers can vary (e.g., some observers may be better able to turn over larger, heavier rocks than others), which can lead to bias in search method and species detection along transects.

(above is from Observer effects section of Stream Transects technique)

Jaeger and Inger (1994) recommend that one person or the same team of observers be used to survey all quadrats for a given study to avoid observer bias.

Advantages:

• Multiple streams can be surveyed in one day.
• Quadrats can be faster and cheaper than other methods (e.g., transects, electrofishing, leaf litter bags) (Cook et al., in prep.).
• Quadrats can provide fairly accurate surface density and census data because all salamanders are removed from the surface and, if raking is employed, the first few inches of the subsurface of the delineated area.
• Compared to other methods (leaf litter bags, box vacuum, etc.), animal mortality is lower.
• With a large number of randomly placed quadrats, potential effects of habitat heterogeneity do not compromise the results (Jaeger and Inger 1994).
• Quadrats are a particularly effective technique for species that burrow into stream substrates, such as adult Desmognathus monticola (Cook et al., in prep.).
• Stream bank quadrats showed higher species richness density, higher total adult densities and higher Desmognathus monticola and D. fuscus densities than transects and leaf litter bags (Cook et al., in prep.). Larger quadrats (4 m2) showed higher total and Eurycea bislineata larval and adult densities compared to transects (15 x 2 m) that spanned stream bank and channel.

Disadvantages:

• Observer bias tends to be high (Chalmers and Droege 2002).
• If destructive sampling is used, there is a fair amount of habitat destruction and it could take a while for salamanders to repopulate the disturbed quadrat area (Mitchell 2000).
• Quadrat work is very labor-intensive and can be somewhat back breaking if sampling many quadrats in a stream with numerous large rocks.
• Difficult to implement population estimation techniques such as capture-recapture or removal sampling because habitat is disturbed while sampling.
• Quadrat technique assumes that all animals are equally catchable or available to the researcher (Jaeger and Inger 1994). In cases where there are escape holes or rocks that can not be lifted because they are too large or too embedded, this may not be the case.
  

Quadrats can be used to provide species presence/absence data, counts of species and life stages, relative abundance, and density (number of individuals/area surveyed). If the quadrat technique involves destructive sampling of the habitat, then it is difficult to employ estimation procedures such as capture-recapture or removal methods. If the quadrat technique does not disturb the habitat, see "Approaches to analyzing your data" in the transect section for further information on population estimation methods that can be used.

• U.S. Geological Survey Amphibian Research and Monitoring Initiative (ARMI) (Cook et al., in prep.)
• Maryland Biological Stream Survey (MBSS) (Southerland et al., in prep.)
• Marshall University in collaboration with the West Virginia Department of Environmental Protection (Tom Pauley, personal communication)

Cook et al. (in prep.) present coefficients of variation for quadrats (1 m2) comparing counts between two streams:

• Cook et al. (in prep.)
• Davic (1983) - artificial quadrats
• Davic and Orr (1987) - artificial quadrats
• Jung et al. (2000)
• Mitchell 1998a,b
• Mitchell 1999
• Parker 1991
• Rocco and Brooks (2000)
• Southerland et al. (in prep)

Chalmers, R. J., and S. Droege. 2002. Leaf litter bags as an index to populations of northern two-lined salamanders (Eurycea bislineata). Wildlife Society Bulletin 30:71-74.

Conant, R., and J. T. Collins. 1998. A Field Guide to Reptiles and Amphibians of Eastern and Central North America. Third Edition, Expanded. The Peterson Field Guide Series. Houghton Mifflin Company, Boston, Massachusetts, U.S.A.

Cook, K. L., R. E. Jung, S. Droege, J. R. Sauer, J. C. Mitchell, M. Crossland, C. J. Leary, M. Larson, and E. Chattin. In prep. Comparison of quantitative methods to survey streamside salamanders in Blue Ridge mountain streams. To be submitted to Herpetologica.

Crother, B. I. (Ed). 2000. Scientific and Standard English Names of Amphibians and Reptiles of North America North of Mexico, with Comments Regarding Confidence in Our Understanding. SSAR Herpetological Circular 29. Pp. iv + 82.

Davic, R.D. 1983. An investigation of salamander guild predation in a North Carolina stream: an experimental approach. Dissertation. Kent State University. 237 pp.

Davic, R. D., and L. P. Orr. 1987. The relationship between rock density and salamander density in a mountain stream. Herpetologica 43:357-361.
Jaeger, R. G., and R. F. Inger. 1994. Quadrat sampling. Pp. 97-102 in: Heyer, R. H., M. A. Donnelly, R. W. McDiarmid, L. C. Hayek, and M. S. Foster (eds.). Measuring and monitoring biological diversity: Standard methods for amphibians. Smithsonian Institution Press, Washington, D.C.

Jung, R. E., S. Droege, J. R. Sauer, and R. B. Landy. 2000. Evaluation of terrestrial and streamside salamander monitoring techniques at Shenandoah National Park. Environmental Monitoring and Assessment 63:65-79.

Mitchell, J. C. 1998a. Amphibian Decline in the Mid-Atlantic region: Monitoring and Management of a Sensitive resource. Final Report, Legacy Resource Management Program, U.S. Department of Defense, Alexandria, VA.

______. 1998b. Guide to Inventory and Monitoring of Streamside Salamanders in Shenandoah National Park. Supplement No. 2 to Amphibian Decline in the Mid-Atlantic Region: Monitoring and Management of a Sensitive Resource. Final Report, Legacy Resource Management Program, U.S. Department of Defense, Alexandria, VA.

Mitchell, J. C. 1999. Amphibian diversity in three montane streams with different levels of acidity, Shenandoah National Park, Virginia. Banisteria 14:28-35.

Mitchell, J. C. 2000. Amphibian Monitoring Methods and Field Guide. Smithsonian National Zoological Park. Conservation Research Center, Front Royal, Virginia, U.S.A.

Parker, M. S. 1991. Relationship between cover availability and larval Pacific giant salamander density. Journal of Herpetology 25:335-357.

Petranka, J. W. 1998. Salamanders of the United States and Canada. Smithsonian Institution Press, Washington, D.C.

Pfingsten, R. A., and F. L. Downs, eds. 1989. Salamanders of Ohio. Ohio Biological Survey Bulletin, New Series 7. 315 pp. Resetarits, W. J., Jr. 1991. Ecological interactions among predators in experimental stream communities. Ecology 72:1782-1793.

Rocco, G. L. and R. P. Brooks. 2000. Abundance and Distribution of a Stream Plethodontid Salamander Assemblage in 14 Ecologically Dissimilar Watersheds in the Pennsylvania Central Appalachians. Final Report. Report No. 2000-4. Penn State Cooperative.

Southerland, M. T., R. E. Jung, J. Vølstad, D. Baxter, G. Mercurio, and I. C. Chellman. In prep. Streamside salamanders as indicators of stream quality in Maryland. To be submitted to Ecological Applications.

Stebbins, R. C. 1998. A Field Guide to Western Reptiles and Amphibians: Field Marks of All Species in Western North America, Includung Baja California. Second Edition. The Peterson Field Guide Series. Houghton Mifflin Company, Boston, Massachusetts, U.S.A.