Life History of the Hellbender, Cryptobranchus Alleganiensis, in a West Virginia Stream
Humphries, W. Jeffrey, Pauley, Thomas K., The American Midland Naturalist
Though locally abundant throughout the high mountains of West Virginia, intensive studies on the natural history and population structure of the hellbender, Cryptobranchus alleganiensis, have not been conducted in the state. From 1998-2000 we conducted a mark-recapture study within a 216 × 18 m stream section in east-central West Virginia using diurnal and nocturnal survey methods. Ninety-nine captures of 44 individuals were recorded. Density estimates ranged from 0.8-1.2 individuals/100 m^sup 2^. The sex ratio was 1.2:1. Sexual dimorphism was apparent, as females were longer and heavier than males. However, the longest males were underweight compared to their predicted mass. This population was highly skewed toward large adults, and larvae and juveniles were not encountered. The mean inter-capture distance was 35.8 m and 95% MCP home range estimates averaged 198 m^sup 2^. Water depth where hellbenders were captured ranged from 16-56 cm and individuals were never captured in heavily silted areas. Hellbender size was not correlated to rock size and not more than one individual was found beneath a single rock. We suggest that more thorough searches focusing on larval and juvenile habitat are needed before accurate assessments of population health can be made in this and other streams in West Virginia.
Hellbenders (Cryptobranchus alleganiensis Daudin) are unique aquatic salamanders of the eastern United States that have experienced substantial population declines because of habitat change and degradation (Nickerson and Mays, 1973a; Wheeler et al, 2003), overcollecting, illegal collecting and incidental take by anglers. They range from southern New York, south to Alabama and Mississippi and west to Missouri and Arkansas (Petranka, 1998). In West Virginia, hellbenders occur statewide with the exception of the eastern panhandle (Green and Pauley, 1987). Hellbenders are habitat specialists, completely aquatic throughout their entire lives and are restricted to streams and rivers with cool, swift flowing water, large rocks for hiding and nesting and an abundance of prey species such as crayfish (Netting, 1929; Green, 1935; Nickerson and Mays, 1973a). Because of their high densities in many streams (Hillis and Bellis, 1971; Nickerson and Mays, 1973a, b; Peterson et al, 1988) and their propensity to target crayfish as their major food source (Green, 1935; Swanson, 1948; Nickerson and Mays, 1973a), hellbenders play an important role in stream ecosystem dynamics.
Hellbenders were once considered common throughout West Virginia (Green, 1934), although, until now, baseline data on population size and structure were not available for any population within the state. Most published studies concerning the natural history of hellbenders (Taber et al, 1975; Nickerson and Mays, 1973a, b; Peterson et al, 1983; Peterson et al, 1988; Hillis and Bellis, 1971) have dealt with populations in Missouri and Arkansas. A study that compared recent surveys to data from ±20 y ago (Wheeler et al, 2003) showed a drastic decline in population sizes in Missouri and illustrated the importance of gathering baseline population structure data. In this study, we discuss aspects of the life history of hellbenders in a West Virginia stream including: (1) population size and density, (2) demography and morphometrics, (3) movement and home range and (4) habitat use to provide data for comparative studies and as a baseline for future population monitoring.
Study site description.-This study took place on a third-order stream in Pocahontas County, West Virginia. We do not report the exact location or name of the stream to avoid attracting collectors to this site. The stream is a tributary of the New River, in the Ohio River drainage. The study area is surrounded by relatively undisturbed forest, and no major development has taken place upstream of the study site except for a U.S. Forest Service road and an abandoned railroad bed. …