Effects of Habitat Features and Landscape Composition on the Population Structure of a Common Aquatic Turtle in a Region Undergoing Rapid Development

Abstract

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.

Predação de ninhos de Trachemys dorbigni (Duméril & Bibron) (Testudines, Emydidae) no extremo sul do Brasil

“…No entanto, estes efeitos podem demorar décadas a serem notados, principalmente quando se leva em conta a presença dos indivíduos adultos (MARCHAND & LITVAITIS 2004).…”

Population structure and allometry of Podocnemis unifilis (Testudines, Podocnemididae) in a protected area upstream Belo Monte dam in Xingu River, Brazil

“…Monitoring such parameters is a core tool used in applied sciences of fisheries biology and wildlife management (Caughley and Sinclair 1994, Cadima 2003, Froese 2004. Population parameters of freshwater turtle species have been comparatively analyzed at temporal and spatial scales to study the effects of particular environmental conditions, habitat alteration and human pressure on the environment (Marchand and Litviatis 2004, Steen and Gibbs 2004, Dodd and Dreslik 2007 another tool used in applied sciences to monitor and evaluate the status of wild populations. The most common is the length-weight relationship (LWR), used to convert lengths into biomass, to determine fish stock status, to compare fish growth amongst areas, and also as a complement to species-specific reproduction and feeding studies (Froese 2006).…”

Movement and habitat use of the snapping turtle in an urban landscape

“…Previous urban studies focused on freshwater turtle species have found distinct patterns in habitat association use (Saumure and Bider 1998;Marchand and Litvaitis 2004a) and earlier research on the Central Canal found non-random habitat associations for both T. scripta and G. geographica (Ryan et al 2008). Similar to T. scripta and G. geographica, our results indicated the importance of upland woodlot habitat in the spatial ecology of C. serpentina in an urban landscape.…”

“…However, the potential negative impacts of urbanization on the biology and population structure of turtle communities can be profound and diverse (Marchand and Litvaitis 2004a;Ryan et al 2008;Steen and Gibbs 2004). Altered features common to urban areas such as roads, increased land use, and subsidized predators are known to impact the distribution, population demographics, and spatial ecology of turtle communities (Marchand and Litvaitis 2004b;Steen and Gibbs 2004;Sterrett et al 2011).…”