SCIURID BURROWS AS ZOOGEMORPHIC ELEMENTS AT MILL RUN (BUCKS COUNTY, PA): NEW DATASET IN THE UPSTREAM REACH

Bioturbation in a riparian environment has direct influence on soil and bank stability, especially for small streams. A new set of complex burrow systems along the northern (right) bank of Mill Run (Tyler State Park, Bucks County, PA) were part of an ongoing research into the zoogeomorphic impact of groundhogs (Marmota monax). We identified 14 inclined tunnels, ten of which were parts of four clusters. Burrow metrics include: entrance length (mean: 30.5 cm), width (27.1 cm), and depth (88.5 cm), dip angle (35.9°), and strike azimuth (average 225.8°), as well as the distance to stream bank (5.8 m) and height of the nearest terrace (1.1 m). There was a general decrease in burrow dimensions and minimum volume of removed sediment with proximity to Mill Run. Most burrows exhibited a strike azimuth roughly perpendicular to the nearest streambank. This study extends previous research upstream and highlights a multi-annual activity of M. monax along a relatively high-traffic section of a riparian zone.