Alabama Waterdog, Black Warrior Waterdog
© 2011 Todd Pierson (1 of 2)
Necturus alabamensis Viosca, 1937
Mark A. Bailey1
1. Historical versus Current Distribution. The type locality of black warrior waterdogs (Necturus alabamensis) is the Black Warrior River, tributary of the Alabama River, near Tuscaloosa, Tuscaloosa County, Alabama (Viosca, 1937; Bailey and Moler, 2003). Black warrior waterdogs range through a restricted segment of north-central Alabama. They apparently are confined to medium–large streams of the upper Black Warrior River system above the Fall Line (Bart et al., 1997). Black warrior waterdogs are known from nine stream segments in four counties: Sipsey Fork and Brushy Creek in Winston County, Locust Fork and Blackburn Fork in Blount County, Mulberry Fork, Blackwater Creek, and Lost Creek in Walker County, and Yellow Creek and North River in Tuscaloosa County (Ashton and Peavy, 1986; Bart et al., 1997). Although their geographic distribution has not been clearly delineated, their range is thought to essentially mimic that of flattened musk turtles (Sternotherus depressus; Ashton and Peavy, 1986; Guyer, 1997, 1998). Additional comments on the identity and distribution of black warrior waterdogs can be found in Gunter and Brode (1964), Brode (1969), Mount (1975), and Guttman et al. (1990). Neill (1963) commented on the distribution of "N. alabamensis," but considered distant Coastal Plain Necturus populations to be conspecific.
2. Historical versus Current Abundance. The historical abundance of black warrior waterdogs is poorly known, but a remarkably large series of 135 specimens was collected in late winter and spring of 1938 in pre-impoundment Mulberry Fork at Cordova, Walker County (Bart et al., 1997). Collection methods, effort, and collector are unknown. Black warrior waterdogs were recently documented (by single specimens) at two localities upstream from this site (Bailey, 1995; Guyer, 1997) and near the upper reaches of Bankhead Lake. However, there is no indication that waterdogs remain present anywhere in the densities that must have existed in 1938 to enable the collection of such a large number of animals. Mount (1981) estimated that sympatric flattened musk turtles no longer inhabited 27% of the stream miles of their historical occupation. The flattened musk turtle recovery plan (U.S.F.W.S., 1990) suggests that only 142 out of 947 stream miles (15%) in the upper Black Warrior drainage may support flattened musk turtle populations, and there is no reason to assume conditions are different for black warrior waterdogs. The status of black warrior waterdogs in impoundments remains poorly known (Guyer, 1997). Bailey (1992, 1995) sampled for black warrior waterdogs at 77 sites scattered across the presumed range. Guyer (1997) re-sampled most of these sites and an additional 55 sites. Virtually all localities where roads cross or approach streams within the species' presumed range were sampled from 1992–'97; of the 122 sites sampled by both researchers, 10 were found to support black warrior waterdogs. At one site, 17 individuals were collected from a 40 m2 area (Guyer and Durflinger, 1999). Distribution, even within the best habitat, appears to be patchy, and abundance may fluctuate from year to year depending on the development of submerged leaf beds (Guyer and Durflinger, 1999).
3. Life History Features.
A. Breeding. Reproduction is aquatic.
i. Breeding migrations. Unknown. Post-hatchling larvae have been collected in December, suggesting late spring or summer nesting (Ashton and Peavy, 1986).
ii. Breeding habitat. Adults with swollen cloacal lips, indicating a sexually active condition, have been collected in the winter (Ashton and Peavy, 1986). Adults collected in winter are usually in or near leaf beds or rock crevices (personal observations).
i. Egg deposition sites. Unknown, but perhaps associated with leaf beds and rock crevices where sexually active adults are found.
ii. Clutch size. Unknown.
C. Larvae/Metamorphosis. Three size classes are evident from the samples taken to date (Guyer, 1997). These presumably correspond to larvae, subadults, and adults. Post-hatching animals (28–50 mm TL) are distinctly striped, closely resembling the larvae of mudpuppies (N. maculosus) of the Tennessee River drainage (Ashton and Peavy, 1986). Black warrior waterdog larvae are black to dark brown on the dorsum with two light dorsolateral stripes beginning at the nostril and extending posteriorly through the eye and terminating on the dorsal fin of the tail. Subadults (50–150 mm TL) lack the bold stripes, but retain traces. Adults (150–248 mm) generally lack stripes and have poorly developed dorsal spotting and a dark line beginning at the nostril, extending through the eye, and dissipating in the gill area. Large adults may be melanistic.
D. Juvenile Habitat. Poorly understood, but larvae typically are collected from submerged leaf beds with rich invertebrate faunas.
E. Adult Habitat. Guyer (1997) reported black warrior waterdogs associated with clay substrates lacking silt, wide and/or narrow stream morphology, increased snail and larval northern dusky salamander (Desmognathus fuscus) abundance, and decreased Asiatic mussel (Corbicula sp.) occurrence. The presence of leaf beds is important.
F. Home Range Size. Unknown.
G. Territories. Unknown.
H. Aestivation/Avoiding Dessication. Aestivation is suspected, but not known. No specimens have been collected during the summer.
I. Seasonal Migrations. Unknown.
J. Torpor (Hibernation). Nonexistent. Adults are active throughout the winter.
K. Interspecific Associations/Exclusions. Unknown.
L. Age/Size at Reproductive Maturity. Not known with certainty, but the adult size class is probably attained in the third winter, or at 2.5 yr. No discernible size classes exist in adults.
M. Longevity. Unknown. The largest specimen on record is a 248 mm (TL) melanistic female, which exceeds the previously known maximum size (Ashton and Peavy, 1986) by almost 90 mm. Although the average growth rate is unknown, this was likely an unusually old individual.
N. Feeding Behavior. Adults are attracted to traps baited with fish flavored cat food, and a captive took a small fish (Elassoma sp.) that settled to the bottom. Captives take earthworms and are probably opportunistic feeders (Ashton and Peavey, 1986).
O. Predators. Unknown.
P. Anti-Predator Mechanisms. Unknown.
Q. Diseases. Unknown.
R. Parasites. Unknown.
4. Conservation. Black warrior waterdogs are confined to medium–large streams of the upper Black Warrior River system above the Fall Line (Bart et al., 1997). There is no indication that waterdogs remain present anywhere in the densities that must have existed historically. Distribution, even within the best habitat, appears to be patchy, and abundance may fluctuate from year to year (Guyer and Durflinger, 1999).
1Mark A. Bailey
Literature references for Amphibian Declines: The Conservation Status of United States Species, edited by Michael Lannoo, are here.
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