Since 2008, Cincinnati Zoo and Botanical Garden staff have been involved in surveying and studying the highly endangered Black Warrior Waterdog (Necturus alabamensis) in Northern Alabama. November 9-12th marked the first trip of the fall/winter field season. Herp department staff members John Staubach, Kristin Bennett and Erik Keyster along with Alle Foster from Children’s Zoo and Chris DeChant of Innovative Zoological Solutions made up the team for this trip.
The black warrior waterdog is named for the Black Warrior River system and is one of the most endangered amphibians in the world. It is now restricted to a small portion of its historic range due to several factors including stream impoundments (dams), introduced predatory game fish, and water quality degradation. Thanks to a grant from Disney Worldwide Conservation Fund and the AZA Conservation Endowment Fund, we are able to continue the work started during our pilot study the previous 2 seasons. Our goals for this trip was to continue our monitoring of the population of black warrior waterdogs (from here forward referred to as BWW) at our study site and to collect specimens of a closely related species, the gulf coast waterdog. Being closely related to the BWW, the gulf coast waterdog will be used as a “model species” to increase our understanding of what is required to reproduce members of this genus in captivity.
Our study site is approximately 7 hours from Cincinnati in the rural hills of northwestern Alabama. The study site is also approximately 40 miles from the nearest hotel, so during “mild” (over 20F at night) weather we generally choose to camp in the nearby Bankhead National Forest. For this trip we spent the first day at our study site collecting specimens of BWWs and habitat data.
BWW are not easy animals to find. They are extremely secretive and nocturnal. Their habitat usage also changes with the seasons. Collecting specimens generally depends on 2 methods- netting in and sorting through hundreds of pounds of submerged leaves or manually flipping large submerged flat rocks. The water temperature during the field season can vary from the 30s F to the 50s F. To say that conditions can sometimes be uncomfortable would be an understatement. Larvae (young waterdogs) are almost exclusively found in underwater accumulations of dead leaves, whereas adults may be found either under large rocks or in leaf accumulations depending on the season. Adults migrate to deeper water during the spring and come back in closer to shore in the winter. We think one of the reasons for this is that the leaf packs that form near the shore offer a great abundance of food for mature waterdogs, especially females that need to build up their fat reserves prior to the breeding season. Temperature also plays a role in movement patterns as shallow water becomes considerably warmer in the summer. The larval waterdogs (at about 3 ½ to 4 cm) also use these leaf packs for locating food as well as a safe place to avoid the dozens of aquatic predators that live in their habitat.
This trip we were fortunately to collect 8 larval BWWs at our study site. This is the highest number of larvae found by our team on one trip. All larvae were released after morphometric data was collected. In addition a portion of the larvae were swabbed for ‘Chytrid’ fungus. The test results will tell us if this population of BWWs has the deadly disease which has been causing amphibian extinctions worldwide. Finding larval BWWs is important because it confirms that breeding did take place earlier this year at our site.
BWWs live in rocky or sandy upland streams with cold clear flowing water. Gulf coast waterdogs typically live in more muddy or sandy streams. The second part of this trip involved driving west from our BWW study site to go find gulf coast waterdogs (GCWs). There are very few rocks in the streams where GCWs occur so the main method for finding them is netting and hauling in pounds and pounds of submerged leaves. The salamanders seem to be found in “pockets” and you may haul in leaves for a long time before hitting the “pocket”. In the meantime we find interesting fish and invertebrates, such as mussels, clams, freshwater shrimp, insect larvae and various fish from darters and madtoms to juvenile gamefish. The diversity of invertebrates and fish can be an indicator of water quality. After a long day and stops at 3 Tributaries of one stream and one stop at another stream, we were successful in collecting many larval and yearling GCWs. We also managed to pull out one adult gulf coast waterdog just as the sun was setting. Finding an adult GCW was our ultimate goal for this part of the trip. After our success we started the drive back to the Bankhead National Forest. The following day we headed back to Cincinnati with our data and swabs from the Chytrid fungus test. Hopefully the results we get from the Chytrid test will confirm that Chytrid fungus is not yet a problem for amphibians in Northern Alabama.
The trip was a success. We confirmed that Black Warrior waterdogs did successfully reproduce at our study site earlier this year. We collected the data needed to further our knowledge of the species and we were able to swab several specimens to confirm or rule out the presence of the deadly amphibian disease Chytridiomycosis. Hopefully we will be returning to Alabama in a month or two when the adult waterdogs start to move in closer to shore to fatten over the winter.