SUBSURFACE (800 MHZ GEORADAR) IMAGING OF A NORTHERN PINESNAKE NEST STRUCTURE, WARREN GROVE RANGE, NEW JERSEY

As part of neoichnological and ecological research of Northern pine snake (Pituophis melanoleucus), adult and juvenile burrows, as well as hibernacula, have been recently investigated using high-frequency (800 MHz) ground-penetrating radar (GPR). However to date, no nest structures have been investigated using this non-invasively subsurface imaging technology. Here we report the first set of surveys of P. melanoleucus nest conducted within an enclosure at the Warren Grove Range, New Jersey. A series of 2D (B-scan) surveys were collected in a 2x2 m grid (line spacing: 10 cm), as part of a pseudo-3D visualization. Adjacent to a partially filled inclined shaft interpreted as a post-oviposition escape burrow, a series of hyperbolic diffractions within the upper 40 cm were interpreted as nest contents. Hatchlings emerged several days following the surveys, confirming the location of the nest and indicating that the velocity reduction and reflection amplitude are related to dielectric contrast between dry aeolian sand matrix and fluid-filled bodies, rather than fluid content of the unhatched eggs. Our study provides an example of a combination of traces associated with colubrid nesting (polychresichnia = adult fugichnia + calichnia + juvenile fugichnia), with implications for interpreting similar biogenic structures in the sedimentary record.