Feral swine harming insular sea turtle reproduction: The origin, impacts, behavior and elimination of an invasive species

Authors

Richard M. Engeman, NWRCFollow
Robert W. Byrd, USDA APHIS Wildlife Services
Jamie Dozier, Tom Yawkey Wildlife Center
Mark A. McAlister, Tom Yawkey Wildlife Center
James O. Edens, USDA APHIS Wildlife Services
Elizabeth M. Kierepka, University of Georgia
Timothy J. Smyser, NWRC
Noel Myers, USDA APHIS Wildlife Services

Date of this Version

2019

Citation

Engeman, R.M.; R.W. Byrd, J. Dozier, M.A. McAlister, J.O. Edens, E.M. Kierepka, T.J. Smyser, and N. Myers. 2019. Feral swine harming insular sea turtle reproduction: The origin, impacts, behavior and elimination of an invasive species. Acta Oecologica 99:103442. doi: 10.1016/j.actao.2019.103442

Comments

U.S. government work

Abstract

Feral swine are among the world's most destructive invasive species wherever they are found, with translocations figuring prominently in their range expansions. In contrast, sea turtles are beloved species that are listed as threatened or endangered throughout the world and are the focus of intense conservation efforts. Nest predation by feral swine severely harms sea turtle reproduction in many locations around the world. Here we quantify and economically assess feral swine nest predation at North Island, South Carolina, an important loggerhead sea turtle nesting beach. Feral swine depredation of North Island sea turtle nests was first detected in 2005, with annual nest monitoring initiated in 2010 documenting nearly total losses to feral swine in 2010 and 2011. The cumulative valuation of annual losses for North Island from 2010 to 2016 ranged as high as $1,166,500. To improve nesting success, an integrated approach for eliminating feral swine was implemented in 2010 and greatly intensified in 2013 by adding federal experts. Removal efforts were challenging due to the island's remoteness and impenetrable habitats, weather, hazards in accessing the island, and wariness of the animals, especially as their population diminished. Removal of the final 11 swine required efforts from 2014 to 2016. Nest predation was highly variable and provided another example of the significance of conditioning by feral swine to sea turtle nests on the consequent severity of nest predation. Even the final individual inflicted heavy losses before his removal. Genetic analyses of feral swine removed from North Island and the adjacent mainland revealed that the island's population did not originate from the nearby mainland, meaning they were (illegally) introduced to the island.