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Efectos de las Características del Hábitat y la Composición del Paisaje sobre la Estructura Poblacional de una Tortuga Acuática Común en un Paisaje Bajo Desarrollo Rápido
Author(s) -
MARCHAND MICHAEL N.,
LITVAITIS JOHN A.
Publication year - 2004
Publication title -
conservation biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.2
H-Index - 222
eISSN - 1523-1739
pISSN - 0888-8892
DOI - 10.1111/j.1523-1739.2004.00019.x
Subject(s) - abundance (ecology) , ecology , turtle (robot) , habitat , geography , population , predation , relative species abundance , vegetation (pathology) , wetland , biology , fishery , medicine , demography , pathology , sociology
We investigated the demography of a common aquatic turtle (Chrysemys picta) along a gradient of urbanization in southeastern New Hampshire. Using a geographic information system and live trapping of turtles, we compared the proportion of males, the proportion of adults, and the relative abundance of turtles in 37 ponds. We used satellite images, aerial photographs, and field visits to describe pond‐specific features and habitat composition up to 2000 m from the perimeter of each pond. The proportion of males was positively associated with the percentage of forest cover within 500 m, greater road density within 100 m, and an index of predator activity at a pond. The proportion of adults in a population was associated with road density within 250 m of the pond and the percentage of the pond perimeter that was forested. Abnormal population structures associated with greater road densities did not necessarily result in lower abundances of turtles in ponds. Turtle abundance increased as the distance to neighboring wetlands decreased and the amount of nesting habitat near pond edges increased. Pond‐specific features also affected turtle abundance where populations were larger in ponds with organic substrates and abundant coverage by shoreline vegetation than in ponds lacking these features. Few turtles were encountered in ponds with an abundance of herbaceous emergent vegetation, and fewer turtles were captured during a summer with abundant precipitation. Suburban and urban developments, with dense road networks and abundant populations of generalist predators (especially the raccoon, Procyon lotor), can alter the structure of aquatic turtle populations. Although these alterations may not result in immediate changes in turtle abundance within a specific population, we suspect that the reduction in recruitment caused by habitat alterations will eventually reduce or eliminate local populations. Even though there are life‐history differences among species of turtles, our results may provide new insight into the causes of recent declines of other turtles.