Nesting preferences of Malaclemys terrapin terrapin in Wellfleet Massachusetts : an ecological study.

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Hegarty, Katy.
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Undergraduate research. , Undergraduate thesis.
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A discrepancy in diamondback terrapin nesting activity at nest sites studied in Wellfleet and Orleans, Massachusetts, was observed during field research. It was noted that nesting activity, as defined by the number of diamondback terrapin nests containing eggs, varied both within and between sites studied. In response to these observations, a study was performed which examined potentially salient ecological parameters of naturally chosen diamondback terrapin nest sites. Ecological parameters of nest sites were studied as a means of better identifying common ecological characteristics of which may contribute to diamondback terrapin female’s nest site selection. Preliminary information was obtained from all naturally chosen diamondback terrapin nest sites studied. Information included: the date of data recovery, the cardinal direction of the nest with respect to slope, the longitude, the latitude, the compaction of the substrate, the type of nest site (garden or natural) and the elevation of the site. Additionally, two samples were obtained from each of the 44 nest site studied; one from a depth of 6 cm, the other from a depth of 12 cm. These depths were selected due to their importance in the architecture of typical diamondback terrapin nest. Samples were obtained a safe distance from the nest itself, so as to not disturb the developing embryos. In the lab, the two samples of substrate for each of the nests sites studied were further analyzed to determine substrate moisture content, percent particle composition and substrate color. Photo analysis of nest sites was performed to determine the percent and type (none, sparse, dense) of vegetation surrounding the nest site. Additionally, Google Earth was used to determine the distance of the nest site to the nearest high tide mark. After compiling ecological data, statistical analyses were performed. The desirable ecological nesting conditions for northern diamondback terrapins were then extrapolated from the results. The results indicate that northern diamondback terrapins prefer southern facing nest sites, less than 60 meters from the high tide mark and under 45 Meters Above Sea Level (MASL) (with a potential preference for nesting elevation between 5 MASL and 15 MASL). Data suggest that nest sites with compaction between 9 PSI and 15 PSI at depths of 6 cm and between 47.5 PSI and 52.5 PSI at depths of 12 cm are preferred by nesting northern diamondback terrapin. Substrate composed primarily of coarse sand, fine sand and coarse silt, with low percent substrate moisture content (typically below approximately 2.31%) and minimal vegetation are posited to be preferred by northern diamondback terrapins in Wellfleet and Orleans Massachusetts. A better understanding of the ideal ecological nesting conditions for the northern diamondback terrapin population of Wellfleet and Orleans, Massachusetts, will improve the restoration efforts of the Massachusetts Audubon by providing them with information which will allow them to construct northern diamondback terrapin gardens better suited to their intended inhabitants.
ii, 88 leaves : illustrations (some color), map.
Includes bibliographical references: leaves 71-72.
Wheaton College (Norton, Mass.)
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