New York Status: Special Concern
Federal Status: Not Listed
Description
Inhabiting only two of New York State's river drainages, the eastern hellbender is an intriguing and bizarre animal and hails as the Americas' largest aquatic salamander. Sexually mature adult hellbenders range in size from 12-29 inches and vary in color from grayish to olive brown and occasionally entirely black. Individuals usually sport dark mottling over the back and upper sides. Several loose flaps of thick, wrinkled skin, which serve a respiratory function, run laterally along either side of the animal. These salamanders are perfectly adapted to their swift flowing stream habitats with their flattened head and body, short stout legs, long rudderlike tail, and very small beady eyes.
Life History
Hellbenders are aquatic organisms throughout their life and remain active year-round. These salamanders generally spend the daylight hours in a natural or self-excavated den beneath large slabs of rock or other shelter-providing objects (logs and boards) on the bottom of streams or rivers. Hellbenders become active after dark, leaving shelter to forage, feeding primarily on crayfish, fish, frogs and a variety of invertebrates. Courtship and breeding begin in late summer. Sexually mature salamanders migrate to and congregate within certain areas to breed. Hellbenders are more conspicuous at this time of the year and some diurnal activity may be observed on overcast days. Males excavate a large nest chamber beneath a rock in preparation for breeding. Gravid females are either attracted to or corralled into the nest sites by the males. Egg laying is initiated about the first week in September. Females simultaneously deposit two long strings of eggs in a softball-sized yellowish mass onto the nest bed. The eggs are 5-7 mm in diameter and number between 150-400 per egg mass. Eggs are fertilized externally as they are being deposited. The breeding pair slowly sways within the nest cavity during fertilization, thereby ensuring a thorough mixing of seminal fluid and eggs. Males then drive out the spent females and remain within the nest cavity to brood and safeguard the eggs until they hatch 68-75 days later in November. The larvae at hatching are approximately 1-1 1/4 inches in length and retain a large yolk sac. Very little is known about larval habits and survivorship, as very few are encountered in the field. It is likely that they either suffer high mortality (falling prey to fish and other predators) during the first years of life, or that they are utilizing some part of the aquatic habitat that makes them difficult to locate and document. Males and females become sexually mature in approximately 5-7 years and can live up to 30 years of age.
Distribution and Habitat
The eastern hellbender's North American range extends from southwestern and southcentral New York, west to southern Illinois, and south to extreme northeastern Mississippi and the northern parts of Alabama and Georgia. A disjunct population occurs in east-central Missouri. A subspecies, the Ozark hellbender (Cryptobranchus a. bishopii), exists as an isolated population in southeastern Missouri and adjacent Arkansas. In New York, the hellbender is found solely in the Susquehanna and Allegheny River drainages, including their associated tributaries. Hellbenders prefer swift running, well oxygenated, unpolluted streams and rivers. An important physical characteristic of these habitats is the presence of riffle areas and abundant large flat rocks, logs or boards which are used for cover and nesting sites.
Status
The hellbender was listed as a special concern species of New York State in 1983. It is listed as Endangered in Maryland, Ohio, Illinois and Indiana and is threatened in Alabama. There is a lack of basic life history and distribution information on these animals. Insufficient historic data on population densities has contributed to a shortage of knowledge on long-term population trends. Available evidence does suggest that numbers of these salamanders have declined and there is little evidence of successful reproduction recently. Among the explanations that have been suggested to account for this apparent decline are pollution of the aquatic habitat, damming of rivers and streams, which eliminates critical riffle areas and lowers the dissolved oxygen content, and the siltation of streams and rivers resulting from agricultural practices and construction work (e.g. bridges and roadwork). An additional problem is the unintentional or intentional and senseless killing by fishermen who accidentally catch hellbenders and erroneously fear that they are venomous.
Management and Research Needs
Continued surveys and long-term monitoring of populations within the Allegheny and Susquehanna River drainages are essential for developing a recovery plan for this species. Of particular importance is an investigation of larval and juvenile habits, survivorship, and habitat use to provide insight into the hellbender's life cycle. Anglers fishing in hellbender habitat should be educated to understand that these salamanders are not dangerous animals nor do they deplete game fish populations. Captive breeding programs coupled with habitat cleanup and reestablishment of riffle areas and adequate stream flow may be warranted.
A radio telemetry study was completed in the Susquehanna River drainage basin. All animals captured were estimated to be 25 years of age or greater, indicating an ageing population with little or no successful reproduction. Hellbenders demonstrated an ability to home after being displaced more than a half mile. They also used a variety of microhabitats including large cover rocks, sunken logs, undercut banks and underwater talus piles for shelter and foraging. Over winter sites included deep water pools and fast flowing riffles that remain open year round.
Additional References
Blais, D. P. 1996. Movement, Home Range, and Other Aspects of the Biology of the Eastern Hellbender (Cryptobranchus alleganiensis alleganiensis): A Radio Telemetric Study. Master Thesis. S.U.N.Y. at Binghamton.
Bishop, S. C. 1941. The Salamanders of New York. New York State Museum Bulletin No. 324, Albany.
Conant, R. and J. T. Collins. 1998. A Field Guide to Reptiles and Amphibians of Eastern and Central North America. Third Edition Expanded. Houghton Mifflin Co., Boston.
Gottlieb, J. A. 1991. A Population Study of the Hellbender Salamander, Cryptobranchus alleganiensis, in the Allegheny River Drainage of New York State. Masters Thesis, St. Bonaventure University, Olean, New York.
Nickerson, M. A. and C. E. Mays. 1973. The Hellbenders: North American "Giant Salamander". Milwaukee Public Museum, Milwaukee.
Petranka, J. W. 1998. Salamanders of the United States and Canada. Smithsonian Institution Press. Washington and London.
Pfingsten, R. A. and F. L. Downs. 1989. Salamanders of Ohio. Bulletin of the Ohio Biological Survey 7(2).
Map adapted from Conant and Collins (1998) and Petranka (1998).
