UNGULATE NEOICHNOLOGY AND ZOOGEOMORPHOLOGY: A CASE STUDY OF BISON

In this first attempt to quality the geomorphic yield of bison, Google Earth^TM historical imagery from 2015 and 2020 was compared in Yellowstone National Park (YNP; USA) and Białowieża National Forest (BNF; Poland and Belarus). GIS analysis revealed that bison trails, wallows, and trample grounds disturb ~27,500 m² at YNP and ~10,700 m² at BNF. Without anthropogenic effects, these mega-traces persist in sand-dominated substrates for 6-26 years. Low sinuosity values (~1.1) and a wide range of lengths (~260 m to >3 km) characterize trails, whereas high aspect ratios (>0.7) and areas of ~17-40 m² distinguish wallows. Trample grounds are larger at ~140-300 m². During the Holocene, >40 million bison inhabited North America at a time, so this study provides a baseline for considering the geomorphic ability of large ungulates. Individual tracks were also examined to observe their morphology in different sand moisture scenarios. The highest marginal ridge (MR) slopes of 33-77° are observed in moist sand (10% moisture by volume), and tracks are the most circular with an aspect ratio of 0.76. MR height in moist sand is ~10-20 mm. Prints indented in wet sand (40% moisture by volume) display similar MR heights of ~5-25 mm, but shallower MR slopes of ~20-45°. The aspect ratio in wet sand is more elliptical at 0.60. In dry sand MR heights and slopes are more varied (~10-40 mm; ~10-50°), and the aspect ratio is 0.63. Ground-penetrating radar (GPR) imaging reveals subsurface anomalies interpreted as undertracks and normal micro-faults. In dry sand, two poorly defined undertracks with 1 cm relief are visible 3-4 cm beneath the tracking surface. No normal micro-faults are present. In moist and wet sand, 4-5 detailed undertracks showing 2-3 cm of relief deform sediments 7-8 cm in depth. Multiple micro-normal faults are present. Aeolian action was simulated on frozen hoofprints and those accentuated with heavy-mineral concentrations (HMC). Tracks exposed to aeolian action exhibit higher HMCs along the MR, which are detectable using low-field bulk magnetic susceptibility (MS). In laboratory, simulated hoofprints indented through a ~1-mm-thick HMC, and subsequently exposed to 1 min wind gusts of 5-10 m/s, form HMCs with MS values of 10s of μSI. Billions of ungulate tracks displaying marginal HMCs are probably preserved, potentially providing a detailed regional paleo-wind record.