Guyer Lab

Department of Biological Sciences, Auburn University

             Indigo Snake Background Information

             The historic range of the Eastern indigo snake (Drymarchon couperi) overlaps that of the Longleaf Pine forest, the ancestral habitat to which these snakes likely evolved. During the fall and winter months of the year, adult indigos use upland pine areas for breeding grounds. Where available, they hang out in gopher tortoise burrows during this time. This makes the presence of gopher tortoises integrally linked with the well being of indigo snakes. The gopher tortoise is considered a keystone species, providing a habitat feature (that burrow) that may be very important to the indigos. These large (5 – 8 feet) and wide-ranging snakes undoubtedly were important predators in the ancestral landscape of the southeastern United States.

             The Eastern Indigo Snake was listed by the U.S. Fish and Wildlife Service as Threatened in 1978 and a recovery plan was developed in 1982. Reasons for their decline include habitat loss, fragmentation, and degradation, over collection, road fatalities, and gassing of gopher tortoise burrows (Hyslop 2006, Speake 1993). A captive propagation program for the purpose of indigo snake recovery began in 1976 under the direction of Dr. Speake at the Alabama Cooperative Wildlife Research Unit and continued through 1987. The purpose of the program was to restock areas in the Southeast that had been extirpated or were low in indigo snake numbers. Adult snakes used for captive breeding  were obtained from zoos, confiscations by the U.S. Fish and Wildlife Service, and wild capture. They were housed, bred, and in some cases the adults were released to the wild; in other cases offspring were released. During the 10 yrs of the project, approximately 500 indigos were released among 9 locations (Speake et al. 1987).

             Since the end of that project, the Alabama Department of Conservation and Natural Resources (ADCNR) has conducted multiple searches of the release locations in Alabama (summarized in: Hart, 2002). Several credible sightings were documented between 2000 – 2005 however, the last confirmed report of an indigo snake sighting was in Coffee County, AL in May, 2000 (Hart 2002).

 

 

 

 

 

 

 

 

 

 

 

 

 

 Conservation Concerns

             Because few places currently maintain viable populations of the eastern indigo snake, reintroduction of these snakes to areas that once harbored them is a reasonable conservation tool. Although such projects have well-known pitfalls (Dodd and Seigel 1991), no other conservation tool is as likely to place this species on a trajectory to achieve eventual delisting. The previous effort at reintroduction likely failed because individuals were distributed at low densities, across too many sites, and with hard releases of juvenile snakes into unseasonal habitat (Speake et al., 1987).

             Despite this discouraging outcome, we are now focusing our efforts on reintroduction to a single site before considering eliminating reintroduction as a management option for this species. The Alabama Comprehensive Wildlife Conservation Strategy (CWCS) identified the threatened Eastern indigo snake as a Priority 1 (Highest Conservation Concern) species and recommended intensive surveys of the reintroduction sites from Speake’s (1987) study. These surveys completed with three probable Alabama sightings (two in Mobile County; one in Washington County) (Hart 2002), leading to the conclusion that the species has essentially been extirpated from the wild of Alabama. Therefore, it appears that successful reintroduction and recovery of this species in Alabama will require an intensive propagation program (Speake 1993). Preliminary data have been generated that show that a restocking effort for this species will take over 10 years and approximately 300 individuals for a productive outcome (unpublished data).

             If reintroduction is to be attempted at a single site, then this site will require a large landscape with diverse habitat patches. Annual home ranges of adult indigo snakes range from 77 – 126 ha for females and 481 – 538 ha for males (Hyslop 2006). Even juvenile snakes require large home ranges (4.1 – 5.4 ha; Smith 1987). Adult snakes exhibit changes in seasonal preference for habitats, favoring xeric upland pine containing gopher tortoise burrows in winter, and lowland, wetter areas in summer months (Hyslop 2006). Hatchlings and yearlings occupy pineland, cypress ponds, fields, and open ponds (Smith 1987). Thus, reintroduction of this species will be a challenge because it will require a large area within a carefully managed landscape.

The Conecuh National Forest (CNF) restoration efforts

             The CNF is in the process of a 30-year plan to restore a pre-settlement native ecosystem composition and structure. This plan includes a managed fire regime, thinning stands and, replacing tree species with young longleaf pine where appropriate. These restoration efforts encompass studies such as herpetofaunal surveys of the Conecuh. Habitats throughout the Conecuh were evaluated and found adequate for reintroduction or restocking efforts of those species rare or recently extirpated from the area (Guyer et al 2007). Additionally, the CNF has healthy populations for the majority of the herpetofauna observed and trapping efforts report no non-native herpetofauna (Guyer et al 2007).

Auburn’s project

             This project is in its infancy this year (2008). We are working in cooperation with Alabama and Georgia DCNR and the Federal Fish and Wildlife Offices to initiate a system whereby we borrow adult female snakes from various locations in Georgia and hold them until they lay their eggs. We then return the females to capture locations and raise the young to approximately 1yr of age. Upon release, they will be permanently marked for follow-up identification and a subset of the snakes will be monitored with telemetry.

 

 

 

 

 

 

 

 

 

 

 

 

 

             Release will happen in two ways. A subset of snakes will be ‘hard released’. This means they will be released at a specific location and just provided the temporary shelter of a hollowed out log, stump, nook or cranny to retreat into on their first day of release, after that it’s up to the snakes to figure things out. The other release technique involves keeping the juvenile snakes inside a 1 hectare, 4 foot tall enclosure for approximately 6 months. During this time, the idea is that the juveniles will become accustomed to the area. They will be supplied food items and have a constant source of water during their stay in the enclosures as well as multiple areas to hide and things to crawl under. In this way we are attempting to ‘head-start’ the indigos. After release from the enclosures, they will be monitored via telemetry to record dispersal.

             These snakes mature after approximately 3yrs of age, and surveys for the adults and reproductive evidence (eggs, unmarked juveniles) will be conducted following release at an appropriate time.

             Auburn is working in conjunction with multiple agencies, federal and private funding, and a conglomerate of indigo aficionados. We appreciate all the support give by these groups and individuals and look forward to continuing our collaborations!

 

 

 

 

 

 

 

 

 

 

 

 

Thank you to everyone involved!

The Georgia DCNR, The Alabama DCNR, Fort Stewart, General Coffee State Park, FWS Regional Southeastern T & E, Project Orianne, Conecuh National Forest, Dean Alessandrini, Marie Rush, Dirk Stevenson, Lloyd Newberry, Terry Norton, John Roberts, Frankie Snow, Christine Sundermann, Joe Abene, Brian Shamblin

Literature Cited

 

Dodd, Jr., C. K., and R. A. Seigel. 1991. Relocation, repatriation, and translocation of amphibians and reptiles: are they conservation strategies that work? Herpetologica 47(3): 336-350.

Guyer, C., M. Bailey, J. Holmes, J. Stiles, and S. Stiles. 2007.Herpetofaunal response to longleaf pine ecosystem restoration, Conecuh National Forest, Alabama.

Hart, B. 2002. Status survey of the Eastern indigo snake (Drymarchon couperi Holbrook), Black pine snake (Pituophis melanoleucus lodingi Blanchard), and Southern hognose snake (Heterodon simus Linnaeus) in Alabama. A report prepared for the ADCNR by the Alabama Natural Heritage Program.

Hyslop, N. L. 2006. Movements, habitat use, and survival of the threatened Eastern indigo snake (Drymarchon couperi) in Georgia. PhD Dissertation, University of Georgia, Athens.

Smith, C. R. 1987. Ecology of juvenile and gravid eastern indigo snakes in North Florida. Masters Thesis, Auburn University, Auburn, AL, USA.

Speake, D. 1993. Indigo snake recovery plan revision. Final report to U. S. Fish and Widlife Service.

Speake, D., D. McGlincy, and C. Smith. 1987. Captive breeding and experimental reintroduction of the Eastern indigo snake. Southeastern Nongame/endangered wildlife symposium. 8 September.