Encyclopedia of Alabama: Black Warrior Waterdog

I wrote an article about the critically endangered Black Warrior Waterdog which is endemic to an area in northern Alabama. Alabama is the 4th most biodiverse state; it ranks 2nd for number of extinctions. This article is published in the Encyclopedia of Alabama.

The Black Warrior waterdog (Necturus alabamensis) is a critically endangered amphibian native to Alabama. Its genus name translates as "swimming tail" and its species name is in honor of it being found only in northern Alabama. Waterdogs, also known as mudpuppies, are members of the Proteidae family of aquatic salamanders that spend the entirety of their lives in the water. This family dates back to the Miocene (23 million to 5 million years ago) and probably earlier.

The Black Warrior waterdog is found only in the Black Warrior River Basin, from which it gets its common name. There are known populations in Sipsey Fork and Brushy Creek in Winston County; Mulberry Fork, Blackwater Creek, and Lost Creek in Walker County; North River and Yellow Creek in Tuscaloosa County; and Locust Fork and Blackburn Fork in Blount County. Several species of waterdog similar to the Black Warrior Waterdog inhabit the Coastal Plain and the Cumberland Plateau regions.

The Black Warrior waterdog was initially identified as a distinct species by biologist Percy Viosca Jr. in 1937. It can be distinguished from similar species by its coloring: it has irregular light spots superimposed with dark rounded spots that form three stripes down its back. Its belly is pale and free from spots. The juvenile has distinct brown stripes running down its back and sides from nose to tail that disappear by maturity. The Black Warrior waterdog's coloring is ideal for the rocky streams it inhabits. It has small nostrils and two small eyes with no eyelids. Each of its four legs has four toes, and it has a long, vertically flattened tail for swimming. Perhaps its most interesting feature is the three feathery external gills on each side of its head. In most salamander species, juveniles have these prominent gills and lose them as adults, but the Black Warrior waterdog has small gills as a juvenile that become more prominent as they reach maturity. Adult Black Warrior waterdogs are approximately 8 inches (20 centimeters) in length.

Black Warrior waterdogs have not been highly studied, therefore little is known about their position in the food web or other aspects of their life cycle. The Black Warrior waterdog's diet is assumed to be similar to that of other species of waterdogs, consisting of small fish, tadpoles, fish eggs, crayfish, and water insects. Black Warrior waterdog populations have been found in close association with populations of mayfly and caddisfly larvae, a likely food source for the waterdogs. No specific predators for the Black Warrior waterdog are known, but similar species are preyed upon by snakes, fish, and other waterdogs.

Black Warrior waterdogs have three life stages: larva, sub-adult, and adult. Although little research has been done on the breeding habits of the Black Warrior waterdog, its requirements can be approximated from the habits of closely related species. Typical breeding sites are aquatic bedrock outcrops or large boulders with sand and gravel underneath them; eggs are deposited under rock slabs or in crevices where the females guard the eggs. Mating occurs in the winter; a single female lays 15-55 eggs between March and May. After the juveniles emerge, they hide in bunches of leaves. Other types of waterdogs reach maturity at approximately 8 weeks, and this is likely the same for the Black Warrior waterdog.

The Black Warrior waterdog is highly vulnerable to a number of human-caused threats to its habitat and lifecycle. Its highly permeable skin and external gill slits make it particularly vulnerable to water pollution, which comes from various sources, including mining, agriculture, forestry, and urban runoff. In extreme cases, excess fertilizer runoff can trigger algal blooms in streams and lakes, increasing water cloudiness and decreasing the oxygen content of the water, smothering nests, and making feeding difficult. Additionally, they are unable to nest in streams that have been modified with concrete reinforcement.

Aside from pollutants, the biggest threat to the survival of this species is habitat fragmentation caused by such human interventions as impassible dams or roadway structures. Habitat fragmentation limits reproduction between populations by isolating them from one another and can limit prey availability and also prevents the waterdogs from fleeing threats.

The species was listed as "endangered" in February 2018 by the U.S. Fish and Wildlife Service. The federal agency also designated 420 miles of river as critical habitat for the Black Warrior waterdog, of which 127 miles were already designated to protect other endangered Alabama freshwater species. A recovery plan for the species has been drawn up by the Fish and Wildlife Service but has yet to be implemented. The Black Warrior waterdog is also listed as critically endangered by the Alabama Natural Heritage Program and the Alabama Department of Conservation and Natural Resources, which found that of 113 surveyed sites in 59 streams, the Black Warrior waterdog was found at only 14.

Additional Resources

Bart, Henry L. Jr., et al. "Taxonomic Nomenclatural Status of the Upper Black Warrior Waterdog." Society for the Study of Amphibians and Reptiles 31 (1997): 192-201.

Guttman, Sheldon I., et al. "An Electrophoretic Analysis of Necturus from the Southeastern United States." Society for the Study of Amphibians and Reptiles 24 (1990):163-75.

Moreno, Michelle C. Durflinger, Craig Guyer, and Mark A. Bailey. "Distribution and Population Biology of the Black Warrior Waterdog, Necturus alabamensis." Southeastern Naturalist 5 (2006): 69-84.

Viosca, Percy Jr. "A Tentative Revision of the Genus Necturus with Descriptions of Three New Species from the Southern Gulf Drainage Area." Copeia 1937 (1937): 120-38.

Neill, Wilfred T. "Notes on the Alabama Waterdog, Necturus alabamensis Viosca." Herpetologica 19 (1963):166-74.