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11 August 2005. Photo by Chris Skelton. Image may be subject to copyright.
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Cambarus harti Hobbs, 1981

Piedmont Blue Burrower

Federal Protection: No US federal protection

State Protection: Endangered

Global Rank: G1

State Rank: S1

SWAP High Priority Species (SGCN): Yes

Element Occurrences (EOs) in Georgia: 12

Habitat Summary for element in Georgia: Complex burrows in floodplain areas with sandy-organic soil


Description

As its name implies, the Piedmont Blue Burrower is deep blue in color, particularly on the claws. The areola is virtually non-existent, and the abdomen appears much narrower than the cephalothorax. The claws of this species may be robust. The Piedmont Blue Burrower reaches a maximum total body length of about 75 mm (3 inches).

Similar Species

None within its range.

Habitat

Complex burrows adjacent to streams and seepage areas, or in low areas where the water table is near the surface of the ground.

Diet

No studies of the Piedmont Blue Burrower are known and the diets of burrowing crayfishes in general are poorly understood. Crayfishes are considered opportunistic omnivores and likely feed on a variety of items, both plant and animal, living or dead. Burrowing crayfishes may forage around the mouths of their burrows, eat organisms that crawl or fall into the burrow, or eat worms that inadvertently tunnel through a burrow wall.

Life History

Burrowing crayfishes inhabit a system of tunnels that may be very complex with several openings to the surface. Openings to the tunnels are often marked by piles of dirt or mud pellets (chimneys). Depending on the soil type and moisture content, these chimneys can reach heights of 6 inches or more. These crayfishes are typically confined to their burrows, but a male must leave its burrow to search for females during the reproductive season. As mentioned above, they may also forage near the opening of their burrow. Active burrows with fresh soil are seen from late spring to late fall, particularly after rain events. During the dry part of the summer, burrow openings may be plugged to help conserve moisture in the burrow. Reproduction probably occurs during the spring and fall, but males in reproductive condition may be found at any time during the year. It is rare to find more than one adult crayfish in the same burrow. When a female crayfish releases her eggs, she attaches them to her swimmerets and is said to be “in berry.” Upon hatching, the juvenile crayfish are attached to the mother by a thread. After the juveniles molt for the second time, they are free of the mother, but stay close and will hold on to her for some time. Multiple juveniles are occasionally found in a single burrow. Eventually they move off on their own. Crayfishes molt 6 or 7 times during their first year of life and most are probably able to reproduce by the end of that year. They molt once or twice a year for the remainder of their lives. Although it is difficult to study burrowing crayfishes, some researchers believe they may live up to 10 years. Males in reproductive condition have been found in April, May, and November and a female carrying eggs was found in May. The smallest breeding male is about 48 mm (1.9 in) in length.

Survey Recommendations

Burrowing crayfishes may be collected by direct excavation of their burrows, by trapping, and during night surveys. Excavating burrows is time consuming and can be very difficult. It also results in destruction of the animals’ burrow. Traps made with PVC pipes or mist nets can be effective. Burrowing crayfishes are sometimes captured around the openings of their burrows on damp nights. Active burrows are found from about mid-March to mid-November if the water table is within about two feet of the surface of the ground.

Range

The Piedmont Blue Burrower is found in creek systems that drain into the Flint and Chattahoochee rivers in Coweta, Fayette, Meriwether, Pike, and Troup counties in west-central Georgia. It was discovered in a tributary to South Creek (Dekalb County, Ocmulgee River system) in 2005 and has subsequently been found in Henry, Monroe, and Newton counties in that system. All locations are in the Piedmont physiographic province.

Threats

Small range size makes this species vulnerable to extinction. Most of the populations are small in size which makes them vulnerable to minor land disturbing activities and alterations in groundwater hydrology.

Georgia Conservation Status

The species is currently known from about 20 locations, many of which appear to harbor small populations. There are populations on property owned by the city of Warm Springs that are somewhat protected and good populations on the Monastery of the Holy Spirit in Rockdale County which are also somewhat protected.

Conservation Management Recommendations

Areas with burrows should be protected from land disturbing activities. Additional surveys and life history studies are needed to better define the range of the Piedmont Blue Burrower and help predict its response to environmental change. Physical differences among populations in the Flint/Chattahoochee river drainages vs. those in the Ocmulgee River drainage warrant a detailed taxonomic analysis using genetics techniques. Environmental education programs should include information about burrowing crayfishes and encourage protection of burrows.

References

Hobbs, H.H., Jr. 1981. The crayfishes of Georgia. Smithsonian Contributions to Zoology 318:1–549.

Hobbs, H.H., Jr. 1989. An illustrated checklist of the American crayfishes (Decapoda: Astacidae, Cambaridae, and Parastacidae). Smithsonian Contributions to Zoology 480:1–236.

Skelton, C.E. 2016. Status Assessment for 14 Crayfish Petitioned for Listing. Final Report. United States Fish and Wildlife Service, Athens, GA. 71 pp.

Taylor, C. A., G.A. Schuster, J.E. Cooper, R.J. DiStefano, A.G. Eversole, P. Hamr, H.H. Hobbs III, H.W. Robison, C.E. Skelton, and R.F. Thoma. 2007. A reassessment of the conservation status of crayfishes of the United States and Canada after 10+ years of increased awareness. Fisheries 32:372–389.

Authors of Account

Christopher E. Skelton

Date Compiled or Updated

C. Skelton, June 2008: original account.

C. Skelton, January 2019: general update of account.

Photo by Georgia DNR – Wildlife Resources