The Louisiana pine snake is a large, non-venomous constrictor endemic to longleaf pine forests of Louisiana and Texas, habitat which has long been decimated by excessive logging and subsequent forest management. Resulting habitat loss and fragmentation along with fire suppression and vehicle-caused mortality have caused drastic population declines, making the Louisiana pine snake one of the rarest snake species in North America. In 2018, the species was listed as a threatened species under the Endangered Species Act.
The Louisiana pine snake has been part of a managed breeding program in the Association of Zoos and Aquariums since 1984 and a Species Survival Plan-managed species since 2000. The goal of this SSP is to sustainably manage an ex situ population while simultaneously supporting in situ conservation of the species through a release program.
Through coordination with the PMC, a portion of each year’s hatchlings are carefully selected on the basis of pedigree for release into suitable protected habitat in a collaborative project with the U.S. Forest Service, U.S. Fish and Wildlife Service, and Louisiana Deptartment of Wildlife and Fisheries. We aim to establish a fully sustainable wild population at the selected field site, and then expand our efforts to other suitable areas.
Maintaining both a stable managed assurance colony and an effective reintroduction program creates difficult challenges for the Louisiana Pine Snake SSP. Our strong partnership with the U.S. Forest Service has been critical to helping overcome these challenges. The Catahoula District of Kisatchie National Forest has entered into a stewardship agreement with the Memphis Zoo in Memphis, Tenn., to support the operation of dedicated breeding facilities and the costs associated with releasing snakes into their natural habitat.
Four core breeding centers were established at Memphis, Audubon, Fort Worth, and Ellen Trout Zoos, all selected due to their historical success in working with the species. Having four centers protects the population from a potential catastrophic event that might occur at any one location. Consolidation of the population from 23 zoos to these breeding centers was determined to be the best strategy for maximizing reproductive output and began in 2016, leaving only a small number of animals, already consistently breeding, at Jacksonville Zoo in Jacksonville, Fla., and Phoenix Zoo in Phoenix, Ariz.
In the years since consolidation, we have seen a significant increase in breeding success. Five years before consolidating the population, there were 107 snakes at 21 facilities. Between 2011 and 2015, total hatches averaged only 23 snakes per year. This was not sufficient to meet either our zoo-managed sustainability goal or our conservation goal.
Today, however, only four years after consolidation began, the population has increased to 306 individuals at the four breeding centers and two satellite facilities, a result of improved breeding success from an average of only 15 percent of paired females reproducing prior to consolidation to 50-75 percent after consolidation. In the three years since fully consolidating the population (2017, 2018, and 2019), hatches have averaged over 100 animals per year.
Because of the increased reproductive success, both the zoo-managed population and the number of annual releases have grown to strong and effective levels. In June 2020, 55 zoo-hatched snakes were released, bringing the total number of releases since 2010 to 178. In 2019, we trapped the first offspring from our releases, marking a critical milestone of success. AZA facilities are now sustainably managing and securing Louisiana pine snakes in zoos while simultaneously contributing to in situ conservation by creating a fully sustainable wild population in protected habitat.
C. Drew Foster is an Animal Curator at Arizona Center for Nature Conservation’s Phoenix Zoo.
Steve Reichling is Director of Conservation & Research at the Memphis Zoo.