Authors:
Isaac Chellman, USGS Patuxent Wildlife Research Center, 12100 Beech Forest Rd., Laurel, MD 20708, ichellman@usgs.gov
Robin E. Jung, USGS Patuxent Wildlife Research Center, 12100 Beech Forest Rd., Laurel, MD 20708, robin_jung@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 transects. These species should not be considered the only amphibians that could be encountered in stream transects. 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. Asterisks indicate terrestrial breeding salamanders that have also been found using stream transects.

Eastern United States:

Ambystoma barbouri, Streamside Salamander; Desmognathus aeneus, Seepage Salamander; Desmognathus fuscus, Northern Dusky Salamander; Desmognathus imitator, Imitator Salamander; Desmognathus monticola, Seal Salamander; Desmognathus ochrophaeus, Allegheny Mountain Dusky Salamander; Desmognathus quadramaculatus, Black-bellied Salamander; Desmognathus wrighti, Pigmy Salamander; Plethodon cinereus, Red-backed Salamander* ; Plethodon cylindraceus, White-spotted Slimy Salamander*; Plethodon glutinosus, Northern Slimy Salamander* ; Plethodon jordani, Jordan's Salamander*; Plethodon richmondi, Southern Ravine Salamander*; Hemidactylium scutatum, Four-toed Salamander; Gyrinophilus p. duryi, Kentucky Spring Salamander; Gyrinophilus p. porphyriticus, Northern Spring Salamander; Pseudotriton m. montanus, Eastern Mud Salamander; Pseudotriton r. ruber, Northern Red Salamander; Eurycea bislineata, Northern Two-lined Salamander; Eurycea cirrigera, Southern Two-lined Salamander; Eurycea l. longicauda, Long-tailed Salamander; Eurycea wilderae, Blue Ridge Two-lined Salamander

Western United States:

Dicamptodon ensatus, California Giant Salamander; Dicamptodon tenebrosus, Coastal Giant Salamander; Rhyacotriton kezeri, Columbia Torrent Salamander; Rhyacotriton olympicus, Northern Olympic Salamander; Rhyacotriton variegatus, Southern Torrent Salamander; Taricha g. granulosa, Rough-skinned Newt; Taricha rivularis, Red-bellied Newt; Plethodon dunni, Dunn's Salamander*; Plethodon vandykei, Van Dyke's Salamander*; Plethodon vehiculum, Western Red-backed Salamander*; Ensatina e. eschscholtzii, Monterey Ensatina*; Aneides ferreus, Clouded Salamander*; Aneides flavipunctatus, Black Salamander*; Batrachoseps attenuatus, California Slender Salamander*; Ascaphus truei, Tailed Frog

The transect technique is a common sampling method for amphibians in terrestrial or aquatic habitats (Jaeger 1994). When used to survey stream amphibians, transects are typically linear areas set up either parallel or perpendicular to the stream, including stream channel, bank or both (Table 1). Various sizes and configurations of transects have been used, and sometimes multiple survey methods are employed along the same transects (Table 1). Transects can provide species presence/absence data, counts of species and life stages, relative abundance, and density (number of individuals/area surveyed). If the number of cover objects turned over is tallied (e.g., using clicker counters), salamander catch per unit effort can also be calculated. Also, if transects are time-constrained (e.g., set at 30 minutes), or the start and end times of the survey are recorded, the number of salamanders per observer-hour effort can be recorded. Capture-recapture or removal estimation techniques can also be used in conjunction with transect surveys (see "Approaches to analyzing your data" below).

A visual encounter survey technique is typically employed within the transect, in which the observer looks for amphibians on the surface and usually also under rocks, logs, and other debris. Cover objects turned over to look for amphibians can be tallied with clicker counters. All cover objects are returned to their original positions to avoid disturbing the habitat. Fine mesh dip nets are the primary tool used to capture the salamanders, but larvae and adults can also be captured with zip-lock bags or by hand. If using a net or zip-lock bag, place the net or bag firmly against the bottom substrate downstream of the cover object. Lift the cover object in front of the net. Sometimes salamanders immediately swim away, but often larvae stay in the area where the rock had been. If you do not see movement, wait for the sediment to settle and look carefully in the area. To capture larval salamanders, position the net or zip-lock bag in front of the salamander's head and gently touch the tail; often they will move forward into the net. Sometimes larvae are swimming around in the open and you can direct them into the net or zip-lock bag. For adults, you can use the same tactic, or you may have to go after them using your hand or dip net if they try to escape. On land, have your net ready to catch amphibians from under overturned rocks. Once you have turned over the rock or log, you might see movement right away, in which case you need to catch it quickly. If a salamander escapes, write down as much information about identification and age (e.g., species, life stage, estimation of total length) as can be positively determined.. If you cannot ascertain the exact species, but know the genus, record the genus and leave the species as unknown (e.g., Desmognathus unknown).

• Travel to and from the stream site
• Laying out transect dimensions (10 to 20 minutes depending on method)
• Habitat, location, and additional information (approximately 10 minutes)
• Collection of salamanders (30 minutes to many hours; highly variable depending on size of transect and technique being used)
• Recording data on salamanders (5 minutes to 1 hour, depending on number caught)
• Marking salamanders [in capture-recapture studies] (< 1 minute/individual to mark, < 1 minute to make sure the mark is visible and correctly identified)
• If removal estimation is used, time spent conducting extra removal passes along transect
• 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 tape (for laying out transect dimensions)
• Flagging (if you wish to mark the transect boundaries or locations on the transect)
• 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

Observers differ in their abilities to identify salamanders, and this can be particularly true for larval forms. To diminish this problem, observers should be trained prior to going into the field and species identification keys should be taken into the field for those who are not completely familiar with how to identify larval and adult salamanders. However, it should be noted that at times even the experts have difficulty discriminating among larval salamanders. Geographic locality and local species occurrence should be factored into 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 under ideal weather conditions for peak salamander activity will provide highest and most consistent salamander counts and estimates. Unfortunately, ideal and standardized weather conditions for conducting transects are not presented 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.

Observer bias could be a possible factor when sampling stream transects. The ability to see or spot salamanders (search image) could vary 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. Training, including observer covariates in analyses, double-observer techniques and the use of some mark-recapture techniques can all be used to reduce this bias.

Advantages:

• Multiple streams can be surveyed in one day.
• Transects yielded higher salamander species richness than electrofishing, quadrats and leaf litter bags (Cook et al., in prep.). Transects were more efficient at sampling E. bislineata, G. porphyriticus and P. ruber adults than quadrats and leaf litter bags, though quadrats typically yielded higher adult densities than transects (Cook et al., in prep.).
• Using removal methods with transects provides fairly accurate population estimates (Southerland et al., in prep).
• Compared to other methods (e.g., electrofishing, vacuum box sampling), salamander mortality in transect surveys is usually lower.

Disadvantages:

• Observer bias tends to be high (Chalmers and Droege 2002).
• It can take a very long time to survey one stream if there are many salamanders in the transect. This is especially true if population estimation work is conducted (e.g., capture-recapture or removal sampling with multiple removal passes).
• Transects often cause habitat disturbance from rock flipping, digging for salamanders, and walking/kneeling in the stream.
• Can be back-breaking work when sampling a stream with numerous large rocks.

Capture-recapture:

With capture-recapture, salamanders are captured and marked individually or batch-marked (in which a unique mark is used during each survey). Marking techniques for stream salamanders include tail notching, toe clipping, tagging with visible implant fluorescent elastomer (VIE) (Northwest Marine Laboratories), or photographing individuals (if they have unique patterns or spots) in such a way that the observer can identify previously caught individuals. Invasive marking techniques are not necessarily recommended because of the potential harm it can cause salamanders. All salamanders are recorded (species, life stage), measured (snout-vent length, total length, etc.) and released. Once individuals are assumed to have mixed evenly back into the population, another capture-recapture survey in the transect is made. Capture-recapture can be conducted just once (in which a Lincoln-Peterson estimator can be used), or multiple times, in which case open (we recommend the software program MARK from Patuxent Wildlife Research Center's Software Archive) or closed (we recommend the software program CAPTURE from Patuxent Wildlife Research Center's Software Archive) population models can be used to estimate the population size for each species and age class within the stream (White et al. 1978; Rexstad and Burnham 1991).

Removal:

Removal methods are less time-consuming than capture-recapture. With removal, an initial pass along the transect is conducted and all salamanders encountered are captured, recorded, and retained in buckets or in individual zip-lock bags. Any escaped individuals should also be documented. The salamanders should be kept in the shade; salamanders can be kept in buckets or resealable bags with adequate water (for larvae) or a small amount of water and an air pocket (for adults). A second pass after a certain period of time is then conducted following the same procedure. Three passes is recommended, but more can be conducted. Once all the passes are completed, salamanders are returned to the transect. To avoid disturbing the stream habitat excessively and to avoid problems with new salamanders moving into the count area during the night, it is probably best to limit removal passes to three passes within a day. Mitchell (2000) suggests that it may be best to limit daytime studies to once per spring or fall season since cover objects may be unattractive to salamanders for several days or weeks following a disturbance.

Ideally, for the removal estimation method to work, the population counts should decrease with each pass (i.e., the population in the transect decreases or is depleted over time). Removal data can be analyzed using Program CAPTURE (removal or Zippen models) to estimate detection rates and population sizes of specific species and age classes sampled within the transect.

• Bury and Corn (1991)
• U.S. Geological Survey Amphibian Research and Monitoring Initiative (ARMI)
• Maryland Biological Stream Survey (MBSS)
• Ohio Environmental Protection Agency
• Dr. Tom Pauley (Marshall University) and the West Virginia Department of Environmental Protection

Hyde and Simons (2001) found extremely high spatial and temporal variation in capture rates of Plethodontid salamanders using terrestrial 50 m long transects (some located within 50 m of streams), though the spatial variation was always greater than temporal variation. They found that natural cover transects had the lowest spatial and temporal variation for all species (except Desmognathus wrighti) of the three diurnal methods they used (natural cover objects along transects, artificial cover boards, and leaf litter searches). Night transects had the lowest variation of any method, but Hyde and Simons (2001) make the point that these coefficients of variation were not directly comparable to the others because the night transects were conducted in conditions ideal for surficial salamander activity.

Cook et al. (in prep.) found coefficients of variation of counts within streams using 50 x 1 m stream bank transects ranging from 0.8 for D. monticola adults, 0.9 for E. bislineata adults to 1.4 for D. fuscus adults. For 15 x 2 m transects spanning the stream bank and channel, coefficients of variation in counts within streams were as follows: 0.5 and 0.7 for E. bislineata larvae and adults, respectively, 0.6 for D. monticola adults, 0.7 for D. fuscus adults, and 0.9 for G. porphyriticus larvae (Cook et al., in prep.).

• Bruce (1995)
• Bury and Corn (1991)
• Corn and Bury (1989)
• Davic (1983)
• Forester (1977)
• Gore (1983)
• Hairston (1986)
• Jung et al. (2000)
• Jung et al. (in prep)
• Kleeberger (1984)
• Krzysik (1979)
• Kucken et al. (1994)
• Ohio EPA (2001)
• Orser and Shure (1975)
• Resetarits (1997)
• Southerland et al. (in prep)
• Waters et al. (2001)
• Welsh (1987)
• Welsh (1990)
• Welsh and Hodgson (1997)
• Welsh and Ollivier (1998)
• Welsh et al. (1997)
• Wilkins and Peterson (2000)

Ashton, R. E., Jr., and P. S. Ashton. 1978. Movements and winter behavior of Eurycea bislineata (Amphibia, Urodela, Plethodontidae). Journal of Herpetology 12:295-298.

Boward, D. M., P. F. Kazyak, S. A. Stranko, M. K. Hurd, and T. P. Prochaska. 1999. From the Mountains to the Sea: The State of Maryland's Freshwater Streams. EPA 903-R-99-023. Maryland Department of Natural Resources, Monitoring and Non-tidal Assessment Division, Annapolis, Maryland, U.S.A.

Bruce, R. C. 1986. Upstream and downstream movements of Eurycea bislineata and other salamanders in a southern Appalachian stream. Herpetologica 42:149-155.

Bruce, R. C. 1995. The use of temporary removal sampling in a study of population dynamics of the salamander Desmognathus monticola. Australian Journal of Ecology 20:403-412.

Burton, T. M., and G. E. Likens. 1975. Salamander populations and biomass in the Hubbard Brook Experimental Forest, New Hampshire. Copeia 1975:541-546.

Bury, R. P., and P. S. Corn. 1991. Sampling Methods for Amphibians in Streams in the Pacific Northwest. USDA Forest Service General Technical Report PNW-GTR-275. Portland, Oregon, U.S.A.

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.

Corn, P. S., and R. P. Bury. 1989. Logging in western Oregon: responses of headwater habitats and stream amphibians. Forest Ecology and Management 29:39-57.

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.
Forester, D. C. 1977. Comments on the female reproductive cycle and philopatry by Desmognathus ochrophaeus (Amphibia, Urodela, Plethodontidae). Journal of Herpetology 11:331-316.

Gore, J. A. 1983. The distribution of Desmognathine larvae (Amphibia: Plethodontidae) in coal surface mine impacted streams of the Cumberland Plateau, USA. Journal of Freshwater Ecology 2:13-23.

Hairston, N. G., Sr. 1986. Species packing in Desmognathus salamanders: experimental demonstration of predation and competition. The American Naturalist 127:266-291.

Harper, C. A., and D. C. Guynn, Jr. 1999. Factors affecting salamander density and distribution in four forest types in the southern Appalachian mountains. Forest Ecology and Management 114:245-252.

Hawkins, C. P., M. L. Murphy, N. H. Anderson, and M. A. Wilzbach. 1983. Density of fish and salamanders in relation to riparian canopy and physical habitat in streams of the northwestern United States. Canadian Journal of Fisheries and Aquatic Sciences 40:1173-1185.

Hom, C. L. 1988. Cover object choice by female dusky salamanders, Desmognathus fuscus. Journal of Herpetology 22:247-249.

Hyde, E. J., and T. R. Simons. 2001. Sampling Plethodontid salamanders: sources of variability. Journal of Wildlife Management 65:624-632.

Jaeger, R. G. 1994. Transect sampling. Pp. 103-107 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.

Keen, H. W. 1982. Habitat selection and interspecific competition in two species of Plethodontid salamanders. Ecology 63:94-102.

Kleeberger, S. R. 1984. A test of competition in two sympatric populations of Desmognathine salamanders. Ecology 65:1846-1856.

Krzysik, A. J. 1979. Resource allocation, coexistence, and the niche structure of a streambank salamander community. Ecological Monographs 49:173-194.

Kucken, D. J., J. S. Davis, J. W. Petranka, and C. K. Smith. 1994. Anakeesta stream acidification and metal contamination: effects on a salamander community. Journal of Environmental Quality 23:1311-1317.

Lowe, W. H., and D. T. Bolger. 2002. Local and landscape-scale predictions of salamander abundance in New Hampshire headwater streams. Conservation Biology 16:183-193

Metts, B. S., J. D. Lanham, and K. R. Russell. 2001. Evaluation of herpetofaunal communities on upland streams and beaver-impounded streams in the upper piedmont of South Carolina. American Midland Naturalist 145:54-65.

Middlekoop, M. J., T. Watts, AND M. Schorr. 1999. Acid mine drainage and its effects on physicochemical conditions and salamander populations in a Cumberland Plateau stream. Journal of the Tennessee Acadamy of Science 73:36.

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.

Murphy, M. L., and J. D. Hall. 1981. Varied effects of clear-cut logging on predators and their habitat in small streams of the Cascade Mountains, Oregon. Canadian Journal of Fisheries and Aquatic Sciences 38:137-145.

Ohio EPA. 2001. Field evaluation manual for Ohio's primary headwater habitat streams. Ohio EPA, Division of Surface Water, Columbus, Ohio, U.S.A.

Orser, P. N. and D. J. Shure. 1972. Effects of urbanization on the salamander Desmognathus fuscus fuscus. Ecology 53:1148-1154.

Orser, P. N., and D. J. Shure. 1975. Population cycles and activity patterns of the dusky salamander, Desmognathus fuscus fuscus. The American Midland Naturalist 93:403-410.

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

Pauley, T. K., and M. Little. 1998. A new technique to monitor larval and juvenile salamanders in stream habitats. Banisteria 12:32-36.

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

Petranka, J. W., M. E. Etheridge, and K. E. Haley. 1993. Effects of timber harvesting on southern Appalachian salamanders. Conservation Biology 7:363-370.

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.

Resetarits, W. J., Jr. 1997. Differences in an ensemble of streamside salamanders (Plethodontidae) above and below a barrier to brook trout. Amphibia-Reptilia 18:15-25.

Rexstad, E., and K.P. Burnham. 1991. Users Guide for Interactive Program CAPTURE. Colorado Cooperative Fish & Wildlife Research Unit, Colorado State University, Fort Collins, Colorado, U.S.A.

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.

Roper, B. B., and D. L. Scarnecchia. 2001. Patterns of diversity, density, and biomass of ectothermic vertebrates in ten small streams along a North American river continuum. Northwest Science 75:168-175.

Smith, J. A., M. L. Baeck, M. Steiner, and A. J. Miller. 1996. Catastrophic rainfall from an upslope thunderstorm in the central Appalachians: The Rapidan storm of June 27, 1995. Water Resources Research 32:3099-3113.

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.

Stebbins, R. C., and N. W. Cohen. 1995. A Natural History of Amphibians. Princeton University Press, Princeton, New Jersey, U.S.A.

Stewart, G. D., and E. D. Bellis. 1970. Dispersion patterns of salamanders along a brook. Copeia 1970:86-89.

Vitt, L.J., J.P. Caldwell, H.M. Wilbur, and D.C. Smith. 1990. Amphibians as harbingers of decay. BioScience 40:418.

Waters, J.R., C. J. Zabel, K. S. McKelvey, and H. H. Welsh, Jr. 2001. Vegetation patterns and abundances in amphibians and small mammals along small streams in a Northwestern California watershed. Northwest Science 75:37-52.

Welsh, H. H., Jr. 1987. Monitoring herpetofauna in woodland habitats of northwestern California and southwestern Oregon: A comprehensive strategy. Gen. Tech. Rep. PSW-100. Pacific Southwest Forest and Range Experiment Station, Forest Service, U.S. Department of Agriculture, Berkeley, California, U.S.A.

Welsh, H. H., Jr. 1990. Relictual amphibians and old-growth forests. Conservation Biology 4:309-319.

Welsh, H. H., Jr., and L. M. Ollivier. 1998. Stream amphibians as indicators of ecosystem stress: A case study from California's Redwoods. Ecological Applications 8:1118-1132.

Welsh, H. H., Jr., L. M. Ollivier, and D. G. Hankin. 1997. A habitat-based design for sampling and monitoring stream amphibians with an illustration from Redwood National Park. Northwest Naturalist 78:1-16.

Welsh, H. H., Jr., and G. R. Hodgson. 1997. A hierarchical strategy for sampling herpetofaunal assemblages along small streams in the western U.S., with an example from northern California. Transactions of the Western Section of the Wildlife Society 33:56-66.

Wetlands Center, Forest Resources Laboratory, Pennsylvania State University, University Park, Pennsylvania, U.S.A. Prepared for U.S. Environmental Protection Agency, Region III, Philadelphia, Pennsylvania, U.S.A.

White, G.C., K.P. Burnham, D.L. Otis, and D.R. Anderson. 1978. Users Manual for Program CAPTURE, Utah State Univ. Press, Logan, Utah, U.S.A.

Wilkins, R. N., and N. P. Peterson. 2000. Factors related to amphibian occurrence and abundance in headwater streams draining second-growth Douglas-fir forests in southwestern Washington. Forest Ecology and Management 139:79-91.