Cooperative Fish and Wildlife Research Units Program:
Education, Research and Technical Assistance for Managing Our Natural Resources


Developing population viability models for eastern indigo snakes

April 2021 - December 2026


Participating Agencies

The eastern indigo snake (EIS; Drymarchon couperi) was federally listed as threatened in 1978, with population declines largely caused by anthropogenically-induced habitat loss. The species has declined throughout its range such that natural populations no longer occur in Alabama, Mississippi, or the Florida panhandle. While EIS persist throughout much of southeastern Georgia and peninsular Florida, ongoing habitat fragmentation, particularly from road mortality, may threaten the long-term viability of remaining populations. As such, empirical modeling approaches are needed to make spatially explicit predictions about the viability of EIS populations.

This project represents a collaboration across multiple state, federal, and non-profit partners to develop spatially explicit population viability models for EIS that incorporate landscape effects on habitat suitability, connectivity, and survival as well as demographic processes such as fecundity and individual growth. The Arizona Cooperative Fish and Wildlife Research Unit is contributing to several components of this project. First, we developed a range-wide connectivity model that explicitly incorporates landscape effects on EIS connectivity. Second, we are developing a survival model to predict EIS survival as a function of road density, sex, and body size. Third, we are assisting in the development of an individual growth model which will allow us to estimate changes in EIS body size over time and thereby predict survival as a function of body size throughout the life of an individual snake. We will continue to collaborate on the development and application of the final population viability model.

Research Publications Publication Date
Chandler, H.C., D. Steen, J. Blue, J.E. Bogan, M.R. Bolt, T. Brady, D.R. Breininger, J. Buening, M. Elliott, J. Godwin, C. Guyer, R.L. Hill, M. Hoffman, N.L. Hyslop, C.L. Jenkins, C. Lechowicz, M. Moore, R.A. Moulis, S. Piccolomini, R. Redmond, F.H. Snow, B.S. Stegenga, D.J. Stevenson, J. Stiles, S. Stiles, M. Wallace, J. Waters, M. Wines, and J.M. Bauder. 2023. The effects of sex and captive-rearing status on growth rates of the imperiled eastern indigo snake (Drymarchon couperi) with implications for ongoing reintroduction. Herpetologica 79:220-230. | Abstract | Publisher Website December 2023
Chandler, H.C., C.L. Jenkins, and J.M. Bauder. 2022. Accounting for geographic variation in habitat associations during habitat suitability and connectivity modeling: A case study with the imperiled eastern indigo snake. Ecological Applications 2022:e2504. | Abstract | Publisher Website January 2022
Bauder, J.M., H.C. Chandler, M. Elmore, and C.L. Jenkins. 2022. Incorporating habitat suitability, landscape distance, and resistance kernels to estimate conservation units for an imperiled terrestrial snake. Landscape Ecology 37:
2519–2533. | Abstract | Publisher Website
August 2022
Presentations Presentation Date
Chandler, H.C., J.M. Bauder, M. Elmore, C.L. Jenkins. 2022. Delineating conservation units for the imperiled eastern indigo snake (Drymarchon couperi). 2022 Southeast Partners in Amphibian and Reptile Conservation Annual Meeting. February 2022
Bauder, J.M., H.C. Chandler, M.R. Bolt, J.E. Hines, N.L. Hyslop, M.L. Legare, M. Mazerolle, B.B. Rothermel, B.S. Stegenga, D.J. Stevenson, and C.L. Jenkins. 2022. Effects of anthropogenic development, body size, and sex on range-wide eastern indigo snake survival. 2022 Annual Conference of The Wildlife Society, Spokane, WA, U.S.A. November 2022