SREL Reprint #2968




Relative vulnerability of female turtles to road mortality

D. A. Steen1, M. J. Aresco2, S. G. Beilke3, B. W. Compton4, E. P. Condon1, C. Kenneth Dodd Jr.5,
H. Forrester6, J. W. Gibbons7, J. L. Greene7, G. Johnson8, T. A. Langen9, M. J. Oldham10, D. N. Oxier11,
R. A. Saumure12, F. W. Schueler13, J. M. Sleeman14, L. L. Smith1, J. K. Tucker15, and J. P. Gibbs16

1Joseph W. Jones Ecological Research Center, Newton, GA, USA
2Department of Biological Science, Florida State University, Tallahassee, FL, USA
3The Pacific Northwest Turtle Project, Portland, OR, USA
4Department of Natural Resources Conservation, Holdsworth Natural Resources Center, University of Massachusetts, Amherst, MA, USA
5USGS/Florida Integrated Science Centers, Gainesville, FL, USA
6Turtle Rescue of New Jersey, Hardwick, NJ, USA
7University of Georgia, Savannah River Ecology Lab, Aiken, SC, USA
8Department of Biology, SUNY Potsdam, Potsdam, NY, USA
9Department of Biology, Clarkson University, Potsdam, NY, USA
10Natural Heritage Information Centre, Ontario Ministry of Natural Resources, Peterborough, ON, Canada
11Arrowhead Reptile Rescue, Ohio Department of Natural Resources Wildlife Rehabilitation,
Cincinnati, OH, USA
12Department of Natural Resource Sciences, McGill University, Ste-Anne-de-Bellevue, Qué, Canada
13Bishops Mills Natural History Centre, Bishops Mills, ON, Canada
14Wildlife Center of Virginia, Waynesboro, VA, USA
15Great Rivers Field Station, Illinois Natural History Survey, Brighton, IL, USA
16SUNY College of Environmental Science and Forestry, Syracuse, NY, USA

Abstract: Recent studies suggest that freshwater turtle populations are becoming increasingly male-biased. A hypothesized cause is a greater vulnerability of female turtles to road mortality. We evaluated this hypothesis by comparing sex ratios from published and unpublished population surveys of turtles conducted on- versus off-roads. Among 38 166 turtles from 157 studies reporting sex ratios, we found a consistently larger female fraction in samples from on-roads (61%) than off-roads (41%). We conclude that female turtles are indeed more likely to cross roadways than are males, which may explain recently reported skewed sex ratios near roadways and signify eventual population declines as females are differentially eliminated.

Keywords: data synthesis; highways; nesting migrations; road mortality; reptile; roads; sex ratio; turtles

SREL Reprint #2968

Steen, D. A., M. J. Aresco, S. G. Beilke, B. W. Compton, E. P. Condon, C. K. Dodd, Jr., H. Forrester, J. W. Gibbons, J. L. Greene, G. Johnson, T. A. Langen, M. J. Oldham, D. N. Oxier, R. A. Saumure, F. W. Schueler, J. M. Sleeman, L. L. Smith, J. K. Tucker, and J. P. Gibbs. 2006. Relative vulnerability of female turtles to road mortality. Animal Conservation 9:269-273.

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