Project

Turtles of Powdermill Nature Reserve

Goal: Long-term research project on the demography and population ecology of turtles at the Powdermill Nature Reserve in Pennsylvania.

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Daniel F Hughes
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Multi-year studies of syntopic species provide a spatiotemporal framework for comparing their demographic responses to the same environmental conditions. We used data derived from 15 years of sampling at an artificial pond matrix in southwestern Pennsylvania to investigate the survival, growth, and ages of Midland Painted Turtles (Chrysemys picta marginata) and Common Snapping Turtles (Chelydra serpentina serpentina). We trapped turtles with baited hoop-nets at a primary wetland, which was the largest and deepest of five artificial ponds in a spatially aggregated matrix at the Powdermill Nature Reserve, a protected site in the Allegheny Mountains. We captured 81 Midland Painted Turtles 162 times, and 43 Common Snapping Turtles 136 times. For both species, apparent survival probabilities were higher for adults (range 79-95%) compared to juveniles (range 57-82%), and higher in females compared to males or juveniles. The average growth rate was highest in juvenile turtles of both species, indicating growth was maximal during periods of the lowest survival. Average growth rates, in general, were slower for Midland Painted Turtles compared to Common Snapping Turtles. Relating body size to age revealed estimates conforming to studies elsewhere and to longevity records based on known-age turtles. We interpret findings at this wetland matrix to represent the demographics of a deme within a fluid and dynamic regional network of demes for these two species and highlight the value of artificial pond networks to the conservation of freshwater turtle metapopulations in Pennsylvania.
Daniel F Hughes
added a project goal
Long-term research project on the demography and population ecology of turtles at the Powdermill Nature Reserve in Pennsylvania.
 
Daniel F Hughes
added a research item
We examined turtle populations occupying eight artificial ponds in Westmoreland County, southwestern Pennsylvania, USA. Beginning in 2005, we used sardine-baited hoop-nets to trap turtles for eight consecutive years at one pond. In 2013, we expanded sampling to include seven additional ponds near the primary study pond. We deployed and checked traps during two 5-d periods at all eight ponds, once in June and again in July 2013. Two of the 12 turtle species native to Pennsylvania were detected, Common Snapping Turtle (Chelydra serpentina serpentina; n = 53) and Midland Painted Turtle (Chrysemys picta marginata; n = 70). We found the Common Snapping Turtle at all surveyed ponds and its abundance was associated with larger, sparsely vegetated ponds. We found the Midland Painted Turtle at six of the eight surveyed ponds and its abundance was associated with smaller, heavily vegetated, ponds. Juveniles of both species were distributed differently than adults and were most common in shallow, heavily vegetated ponds with low visibility and were absent or nearly so from deep ponds with little emergent vegetation favored by adults. Across eight years, the number of juveniles was low or they were absent from the primary study pond, yet recruitment was likely maintained through a nearby nursery pond favored by juveniles. In this heterogeneous pond matrix, turtle population structures were strongly influenced by certain physical features of the ponds to the benefit of one life stage over another. Species composition was influenced in a likewise manner. Inter-pond movements were likely encouraged by local habitats and resident population structures. We suggest that ponds can be constructed or modified to accommodate one or more life stages of these turtle species, and enhance opportunity for pond colonization and gene flow among ponds.
Daniel F Hughes
added a research item
We studied nesting activities and measured afternoon nest-temperatures of the midland painted turtle (Chrysemys picta marginata), common snapping turtle (Chelydra serpentina serpentina), and eastern box turtle (Terrapene carolina carolina) from a wetland matrix during May–November 2013 at the Powdermill Nature Reserve in western Pennsylvania, USA. Nesting turtles were encountered during a 36-day period (2 June–8 July). The aquatic turtle species nesting season spanned 17 days (2–18 June). In general, nests were located in areas lacking extensive vegetation and near wetlands. Across all species, successful nests constituted 15% (n = 5), abandoned nests 53% (n = 18), and depredated nests 32% (n = 11). Nest losses to predation were highest for C. s. serpentina at 75% (6/8 nests). Mean nest temperatures were lowest for C. p. marginata and T. c. carolina. Nest successes were highest for C. s. serpentina at 42% (19/45 eggs) and hatchlings emerged from these nests by late August. By the first freeze in November, 40% (4/10 eggs) of T. c. carolina eggs hatched and hatchlings remained in the nest to overwinter, whereas none of the eight C. p. marginata eggs had hatched by then. Our results from a single site are comparable to findings from other regions and for Pennsylvania generally. Our findings also provide the basis for examining responses in nesting phenology to environmental perturbations, most relevant being climate change.