T ur tles were notched at the rear of the posterior marginal scutes of the carapace to indicate previous capture (Cagle 1939).
The Road To Character David Brooks Download Citation CopyGibbs State University of New York College of Environmental Science and Forestry Download full-text PDF Read full-text Download full-text PDF Read full-text Download citation Copy link Link copied Read full-text Download citation Copy link Link copied Citations (259) References (47) Figures (3) Abstract and Figures Road mortality has the potential to alter the structure of turtle populations because turtle populations are highly sensitive to additive sources of adult mortality.
To address the issue, we captured painted turtles ( Chrysemys picta; n 174) and snapping turtles ( Chelydra serpentina; n 56) in 18 wetlands surrounded by low road density (1.5 km roadskm2 of landscape) and 17 wetlands surrounded by high road density (1.5 kmkm2) in central New York in 2002. High road density was associated with male-biased sex ratios in painted turtles (74 vs. Disproportionate road mortality of females on nesting migrations is the most likely cause of skewed sex ratios. Mean SD (n a ). Morphological parameters and abundance of snapping turtles in relation to road density at 35 wetlands in central New York, 2002. Steen Author content All figure content in this area was uploaded by David A. The Road To Character David Brooks For Free Public FullDiscover the worlds research 20 million members 135 million publications 700k research projects Join for free Public Full-text 1 Content uploaded by David A. Steen Author content All content in this area was uploaded by David A. STEEN AND JAMES P. GIBBS 350 Illick Hall, 1 Forestry Drive, State University of New Y ork College of Environmental Science and Forestry, Syracuse, NY 13210, U.S.A. Abstract: Road mortality has the potential to alter the structure of turtle populations because turtle popula- tions are highly sensitive to additive sources of adult mortality. Disproportionate road mortality of females on nesting migrations is the most lik ely cause of skewed sex r atios. When such movements intersect with roads, turtles are partic- ularly vulnerable to road-associated mortality because of their relatively slow travel speed. Individual turtles are killed frequently on roads (e.g., Goodman et al. Ashley Robinson 1996) because many turtles nest during the hours surrounding dawn and dusk (Legler 1954; Ernst 1986), times that correspond to 1143 Conservation Biology, Pag es 11431148 Volume 18, No. Although male aquatic turtles occasionally travel overland (Gibbons 1986), sexually mature females completing annual nesting migrations are likely much mor e susceptible to vehicle- induced mortality than males. Moreover, gravid females of some aquatic species may make multiple excursions overland prior to actual nesting (Christens Bider 1987; Reese W elsh 1997). Together, these movements expose turtles, particularly females, to high levels of road mortal- ity ( Haxton 2000). Road networks within the United States are undergo- ing a steady expansion (National Research Council 1997), but whether this plays a role in the imperilment of turtles in the United States, a country of particularly high turtle diversity and imperilment (Ernst et al. Gibbons et al. 2000). Gibbs and Shriver (2002) es- timated through computer modeling that many species of turtles may be subjected to road mortality that ex- ceeds sustainable levels, but empirical confirmation of their predictions is lacking. Our objective was to conduct field studies to determine whether the density of roads surrounding freshwater wetlands affects the population structure of turtles. To this end, turtle abundance, size, sex ratio, and biomass were contrasted among w etlands in landscapes of high and low road density. Wetlands were 1 13 ha in area, w ere dominated by emergent vegetation, and had no ov erland connections to other bodies of water. For each turtle captured, we took several measurements, including carapace and plastron length. W e then weighed turtles with hand-held scales and sexed them on the basis of external secondary sexual characteristics. In addition to recording the num- ber of leeches on each turtle, we noted the percent cover of algal growth on the carapace.
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