COMPARATIVE AERIAL IMAGE ANALYSIS OF BISON WALLOWS IN NORTH AMERICA (YELLOWSTONE NP, WY, USA) AND EUROPE (BIAŁOWIEŻA NP, POLAND)

Over the past century, two extant species of bison have experienced a substantial increase in their populations (both domesticated and wild). This translates into greater impact, through both their range expansion and focused activity (zoogeomorphic yield), on landforms and ecosystems in North America (plains and woods subspecies of Bison bison) and Eastern Europe (zubr or wisent, Bison bonasus). This study presents a satellite-aided comparative analysis of wallows, as part of a larger study aimed at assessing their growing role as keystone zoogeomorphic agents, as well as a reference for reconstructing their paleo-environmental impact. At Yellowstone National Park (Wyoming, USA), within a randomly selected 1x1 km quadrant, >150 wallows ranged in area between 10-80 m² , with larger tramplegrounds averaging ~150 m². At Białowieża National Park (Poland/Belarus), European bison occupy outwash plains that are similar to many Pleistocene periglacial landscapes. Outside the wooded areas, the wallows range between 18-90 m². The average width/length ratio of 0.74 may offer a diagnostic metric for distinguishing these features from nearly circular depressions of other biogenic and abiotic origin. In addition to wallows, extensive trails produced through pediturbation by migrating bison herds, especially considering their past numbers and ranges, have been long considered important landscape elements. Trail segments clearly visible in aerial images range between 200-2,000 m in length, with time-series analysis serving as an important reference database to test the potential of specific segments to be converted into drainage elements.