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|Various Techniques for Hellbenders|
Cryptobranchus Alleganiensis, Hellbender
Subspecies: Cryptobranchus a. alleganiensis, Eastern Hellbender; Cryptobranchus a. bishopi, Ozark Hellbender
Hellbenders live in permanent streams where they stay under flat rocks in riverbeds during the day and emerge at night to forage for food. Mating occurs in late summer and eggs are deposited from late August to early November. Males excavate nests under rocks or logs in streams where females lay connected, marble-sized eggs resembling a beaded necklace.
Surveys for hellbenders can be conducted during day or night searches. Day searches usually involve turning rocks and other cover objects and night searches generally are conducted by searching the bottom of riffles and shallow pools with flashlights. A variety of techniques have been used through the years to search for hellbenders. While one technique may work successfully in one part of the range of hellbenders, it may not work in another part. It is usually necessary to try a variety of techniques to successfully find and capture hellbenders.
Habitat types dictate appropriate methods for surveying for hellbender.
For example, deeper water requires snorkeling or scuba diving and surveys
in shallow water should include turning rocks and electroshocking. Also,
the number of inaccessible hiding spots may influence the success of some
techniques. For example, Humphries (1999) demonstrated that nocturnal
surveys were more successful than turning rocks in a West Virginia stream
because of the intricate makeup of the stream bottom. Snorkeling is the
best method for larval counts; all other methods probably terribly underestimate
Hellbenders can be observed moving along the bottom of streams in deep water by scuba diving (Trauth, Wilhide, and Daniel 1992a) in shallow water, by looking through a five-gallon plastic bucket with clear plexiglas bottom, snorkeling or skin-diving (Nickerson, et al. 2002), and wading and searching. Usually hellbenders are not observed moving about in the daytime and it is necessary to move cover objects.
Turning cover objects involves carefully moving rocks, logs, and other objects such as non-natural items (viz. large pieces of trash) and capturing hellbenders by hand, dipnets, or seines. Cover objects can be moved with the aid of potato hoes (herp rakes) (Reese 1906, Smith 1907, Bishop 1941, Hillis and Bellis 1971, Nickerson and May 1973, Taber et al. 1975); crowbars (Peterson 1988); log peaveys (Humphries1999); log cant hooks (Pauley and Watson, unpublished data); or by hand (Peterson 1987, 1988; Peterson, et al. 1989; Trauth, et al. 1993; Bothner and Gottlieb, 1991). Specimens observed by turning rocks but capture methods not described are reported by Swanson (1948), Peterson, et al. (1983), Peterson, et al. (1989), Trauth et al. (1992b). Rocks should be placed back in original positions to reduce the build up of silt around rocks. Accumulation of silt around the upstream part of a rock may allow too much flow under them and hellbenders may abandon rocks with too much flow.
Hellbenders can be captured by hand, which usually involves grabbing specimens behind the head (Peterson, et al. 1988), seines (reported in collection records of the Carnegie Museum of Natural History in Williams, Gates, and Holcutt 1981), by fisherman’s hoopnet (Trauth, Wilhide, and Daniel 1992a), and by long-handled dipnets (Peterson, et al. 1989, Taber, et al. 1975, Hillis and Bellis 1971). T.K. Pauley recommends using a “D” frame dipnet with two bags sewn together end to end. This allows for a deeper net and prevents hellbenders from jumping from the net. One person could conceivably collect hellbenders by hand, i.e., one person could turn the stones and capture specimens, but 2 people would be more ideal. With rock turning tools, 2 people are required, one to turn rocks and one to capture specimens by hand or with a dipnet or seine.
After completing one pass though an area during a survey, the same area should be checked again. Humphries has found hellbenders walking around after the first pass. He presumes he chased them out from cover objects without noticing them the first time.
Electroshocking involves at least 2 people, one person works the electroshocker and one captures stunned hellbenders with an insulated dipnet or seine (Williams, Gates, and Holcutt, 1981; Gates, Holcutt, Stauffer, Jr., and Taylor 1985).
Many fishermen have reported catching hellbenders on fishing lines with hooks. Some literature reports on the use of this method (Gates, Holcutt, Stauffer, Jr., and Taylor 1985; Ferguson 1961). Bait generally used includes crayfish and small fish. We do not recommend this method because of the distress of removing the hook from captured specimen. Other capture methods that have been used but that we do not recommend include spearing hellbenders with a pitchfork (Green, 1935) and shooting them with a pistol or rifle (Netting, 1929).
Hellbenders are largely active at night when they forage on the bottom of streams (Humphries and Pauley 2000; Noeske and Nickerson 1979; Smith 1907; Swanson 1948). They can be located by wading in shallow water and searching the bottom with flashlights and can be captured by hand as described above under the Day Searches Section. Since hellbenders are active at night, they are captured more easily with dipnets and seine than by hand.
Things that could bias your counts
Adults are easily identified and should not be confused with other species of salamanders that inhabit streams. Identification of larvae can be more challenging. Larvae are generally about 30 mm total length at hatching and have a fleshy fold of skin on the posterior edge of the forelimb. Mudpuppies (Necturus spp.) are the only other large salamanders that may inhabit the same habitats but they lack the typical hellbender characteristic of lateral folds of skin and they have external gills and 4 toes on the hind feet.
Nocturnal and diurnal surveys could be impaired during high water and “silty or muddy” conditions because of reduced visibility and ability to wade in streams. Hellbenders can be active during overcast days (Nickerson and May 1973). Raindrops break the surface of steams thus reducing visibility during day and night surveys.
Time of year
Annual activity patterns of hellbenders vary from diurnal to nocturnal periods. Humphries and Pauley (2000) found them to be most active at night during May and June. Other researchers report hellbenders to be more active in the day and night during the breeding season in late summer (Green 1934, Bishop 1941, Nickerson and May 1973, and D. Madison, pers. comm. as reported in Humphries and Pauley 2000). Since hellbenders are more active during the breeding season, sightings may be more common at breeding sites. Humphries found at least one active hellbender during the day on 5 visits to a breeding site in North Carolina.
Time of day
Hellbenders are chiefly nocturnal and take refuge under cover objects during the day (Bishop 1941, Smith 1961) but will emerge in the daytime during the breeding season in late summer Green 1934, Bishop 1941, Nickerson and May 1973, and D. Madison, pers. comm. as reported in Humphries and Pauley 2000).
Logging, road construction, acid mine drainage, and development activities can suffocate eggs and oxygen exchange in gills of larvae and low pH can prevent development of eggs and larvae and cause stress or death of adults. Wheeler et al. (2003) found a 70% decline in populations over 20+ years in 3 streams in Missouri. Possible causes are habitat degradation such as siltation and eutrophication.
When establishing a monitoring program one should measure water visibility. Changes in water quality as a result of timbering activities, road construction, etc., could alter habitats over time due to silt loads. While the number of hellbenders could remain constant, detectability of salamanders could change. For example, if one started counting salamanders when a stream was clear and then over the years that stream became cloudy counts of salamanders could go down, not because of real declines, but because the ability to capture or count them has decreased.
Experienced collectors may be more successful in spotting hellbenders and catching them, especially by hand. Agility in water and quickness with dipnets are critical to successfully capture hellbenders. Surveys are physically demanding especially when turning large rocks and carrying an electroshocker. Sizes of rocks one investigator may be capable of turning may exceed the size of another person’s capability. To assure that future data are consistent and eliminate bias, sizes of rocks turned should be measured and recorded in any monitoring program. For safety reasons such as back strain, it might be prudent to establish a limit on the size of rocks that will be moved.
Advantages of search methods:
Advantages of capture methods
Disadvantages of search methods:
Disadvantages of capture methods:
Searches by methods described above may be by either time or area constraints x number of investigators. This could provide some data on relative abundance of hellbenders . Estimating densities requires some method of mark and recapture technique such as passive integrated transponders (PIT) tags. Gender determination, body-size measurements (total length and snout-to-vent length) and weight could provide data to determine reproductive status and possible success of the survival of populations. These methods could only provide some data on relative abundance in a general way as detectibly and ability to capture specimens are likely to vary from place to place.
Ben Wheeler and Alicia Mathis, Southeastern Missouri State University, Springfield, MO.
To our knowledge, there are no published techniques for count variations for hellbenders.
Bishop, S.C. 1941. Salamanders of New York. New York State Museum Bulletin 324:1-365.
Bothner, R.C. and J.A. Gottlieb. 1991. A study of the New York State populations of the hellbender. Proceedings of the Rochester Academy of Science 17(1):41-54.
Ferguson, D. 1961. The herpetofauna of Tishomingo County, Mississippi, with comments on its zoogeographic affinities. Copeia 1961(4):391-396
Gates, J.E., C.H. Holcutt, J.R. Stauffer, Jr., and G.J. Taylor. 1985. The distribution and status of Cryptobranchus alleganiensis in Maryland. Herpetological Review 16:17-18.
Green, N.B. 1934. Cryptobranchus alleganiensis in West Virginia. Proceedings of the West Virginia Academy of Science 7: 28-31.
Green, N.B. 1935. Further notes on the food habits of Cryptobranchus alleganiensis. Proceedings of the West Virginia Academy of Science 9: 36.
Hillis, R.E., and E.D. Bellis. 1971. Some aspects of the ecology of the hellbender, Cryptobranchus a. alleganiensis, in a Pennsylvania stream. Journal of Herpetology. 5: 121-126.
Humphries, W.J. 1999. Ecology and population demography of the hellbender, Cryptobranchus alleganiensis, in West Virginia. M.S. Thesis, Marshall University, Huntington, WV.
Humphries, W.J. and T.K. Pauley. 2000. Seasonal changes in nocturnal activity of the hellbender, Cryptobranchus alleganiensis, in West Virginia. Journal of Herpetology. 34(4):604-607.
Netting, M.G. 1929. The food of the hellbender, Cryptobranchus alleganiensis (Daudin). Copeia. 170:23-24.
Nickerson, M.A., and C.E. Mays. 1973. The hellbenders: North American "giant salamanders". Milwaukee Public Museum Publications in Biology and Geology. 1: 1-106.
Nickerson, M.A., K.L. Krysko, and R.D. Owen. 2002. Ecological status of the hellbender (Cryptobranchus alleganiensis) and the mudpuppy (Necturus maculosus) salamanders in the Great Smoky Mountains National Park. Journal of the North Carolina Academy of Science 118:27-34.
Noeske, T.A. and M.A. Nickerson. 1979. Diel activity rhythms in the hellbender, Cryptobranchus alleganiensis (Caudata: Cryptobranchidae). Copeia 1979:92-95.
Peterson, C.L. 1987. Movement and catchability of the hellbender, Cryptobranchus alleganiensis. Journal of Herpetology. 21(3): 197-204.
Peterson, C.L. 1988. Breeding activities of the hellbender in Missouri. Herpetological Review. 19(2):28-29.
Peterson, C.L., C.A. Ingersol, and R.F. Wilkinson. 1989. Winter breeding of Cryptobranchus alleganiensis bishopi in Arkansas. Copeia. 1989: 1031-1035.
Peterson, C.L., and R.F. Wilkinson. 1996. Home range size of the hellbender (Cryptobranchus alleganiensis) in Missouri. Herpetological Review. 27(3):126-127.
Peterson, C.L., R.F. Wilkinson, Jr., M.S. Topping, and D.E. Metter. 1983. Age and growth of the Ozark Hellbender (Cryptobranchus alleganiensis bishopi). Copeia. 1983:225-231.
Peterson, C.L., D.E. Metter, B.T. Miller, R.F. Wilkinson, and M.S. Topping. 1988. Demography of the Hellbender Cryptobranchus alleganiensis in the Ozarks. The American Midland Naturalist. 119(2):291-303.
Peterson, C.L., J.W. Reed, and R.F. Wilkinson. 1989. Seasonal food habits of Cryptobranchus alleganiensis (Caudata: Cryptobranchidae). The Southwestern Naturalist 34(3):438-441.
Reese, A.M. 1906. Anatomy of Cryptobranchus allegheniensis. American Naturalist 40(472):287-326.
Smith, B.G. 1907. The life history and habits of Cryptobranchus alleganiensis. Biological Bulletin. 13: 5-39.
Smith, P.W. 1961. The amphibians and reptiles of Illinois. Bulletin of Illinois Natural History Survey 28(1):1-298.
Swanson, P.L. 1948. Notes on the amphibians and reptiles of Venango County, Pennsylvania. The American Midland Naturalist 40:362-371.
Taber, C.A., R.F. Wilkinson, Jr., and M.S. Topping. 1975. Age and growth of hellbenders in the Niangua River, Missouri. Copeia. 1975: 633-639.
Trauth, S.E., J.D. Wilhide, and P. Daniel. 1992a. Cryptobranchus bishopi (Ozark Hellbender). Herpetological Review. 23(4):121.
Trauth, S.E., J.D. Wilhide, and P. Daniel. 1992b. Status of the Ozark Hellbender, Cryptobranchus bishopi (Urodela: Cryptobranchidae), in the Spring River, Fulton County, Arkansas. Proceedings Arkansas Academy of Science. 46:83-86.
Trauth, S.E., J.D. Wilhide, and P. Daniel. 1993. The Ozark Hellbender, Cryptobranchus bishopi, in Arkansas: Distributional Survey for 1992. Bulletin of the Chicago Herpetological Society 28(4):81-85.
Wheeler, B.A., E. Prosen, A. Mathis, and R.F. Wilkinson. 2003. Population declines of a long-lived salamander: a 20+-year study of hellbenders, Cryptobranchus alleganiensis. Biological Conservation 109:151-156.
Williams, R.D., J.E. Gates, and C.H. Hocutt. 1981. An evaluation of known and potential sampling techniques for hellbender, Cryptobranchus alleganiensis. Journal of Herpetology. 15(1):23-27.
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