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 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.

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.

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.
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.