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Road density not a major driver of Red-eared slider (Trachemys scripta elegans) population demographics in the Lower Rio Grande Valley of Texas


Mali, Ivana; Dickerson, Brian E.; Brown, Donald J.; Dixon, James R.; Forstner, Michael R. J. 2013. Road density not a major driver of Red-eared slider (Trachemys scripta elegans) population demographics in the Lower Rio Grande Valley of Texas. Herpetological Conservation and Biology. 8(1): 131-140.

In recent years there have been concerns over the conservation and management of freshwater turtle populations in the state of Texas. In 2008 and 2009, we completed several investigations addressing anthropogenic impacts on freshwater turtles in the Lower Rio Grande Valley (LRGV) of Texas. Here, we use a model selection approach within an information-theoretic framework and simple linear regressions to investigate effects of road density and number of surrounding water bodies on relative abundance and sex ratio of Red-eared Sliders (Trachemys scripta elegans). We sampled 36 sites across three counties in the LRGV. We used a GIS (Geographic Information System) and county road maps to estimate the total length of road within 1 km radius circular buffers centered on the midpoint of trap lines at each site and hydrology maps to estimate number of water bodies within the 1 km buffer. Based on model selection results, the number of surrounding water bodies best explained the relative abundance of turtles, while road density best explained sex ratio differences. However, predictors in both models showed little explanatory power. Our failure to identify road density as a strong predictor of decreased turtle abundance gives additional weight to conclusions drawn from our recent work that suggested declines of Red-eared Sliders in the LRGV are due to commercial harvest and land use changes.

Keywords: conservation, GIS, human impacts, turtles, urbanization


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http://www.fs.fed.us/rm/pubs_other/rmrs_2013_mali_i001.pdf

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Title: RMRS Other Publications: Road density not a major driver of Red-eared slider (Trachemys scripta elegans) population demographics in the Lower Rio Grande Valley of Texas
Electronic Publish Date: June 26, 2013
Last Update:
June 26, 2013

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