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