A NEW EXPERIMENTAL SETUP FOR TESTING THE EFFECT OF MEDIA CONSISTENCY ON AVIAN TRACK MORPHOLOGY AND LINKING TRACES PRODUCED TO BEHAVIOR

An issue with collecting modern bird tracks is the difficulty in connecting video footage and photographs to tracks produced and the environmental conditions at the time of track production. A new experimental setup using a collapsible tray ~123 cm by ~72 cm and ~4 cm deep, a monopod ~150 cm tall, and a digital video camera, captures tracemaker, trace, and behavior all at once. The tray contains sediment that can be wetted to produce different types of media (=substrate) consistency, which can be measured before and after track production. This experimental setup is portable and can fit inside a small car. The experimental setup can be used in laboratory settings, controlled outdoor settings (e.g., aviary or coop), and uncontrolled natural settings (e.g., on a river bank or along a lakeshore). Several track-making experiments were performed to test this setup using domestic chickens (Gallus gallus) to examine the variation of track morphology with media consistency and type. An experiment was also performed using Mourning Doves (Zenaida macrocura) to test if the tray can be used in natural, uncontrolled settings. The results of the controlled experiment using G. gallus indicate that the finer the sediment size, the better detail is preserved—in coarse sand, no pad impressions are preserved at all, whereas in medium sand, fine sand, and mud, pad impressions are preserved. In mud, scale and claw impressions are also preserved. In dry sediment the digit impressions were significantly longer and wider than the digit impressions of saturated and moist sediment, and ended in blunt, rounded tips. In saturated sediment, the sediment was too elastic to hold fine detail, however, the digit impressions tapered to points. In wet and moist sediments, the potential for pad impression preservation was high, however, preservation of such features was less likely if the sediment became too dry. Behaviors observed in the controlled experimental setup included sinuous walking, walking, running, start-stop walking, landing, and takeoff trackways. Start-stop walking did not produce side-by-side tracks and was the result of a bird pausing in midstride. Takeoff and landing behaviors also did not necessarily produce side-by-side tracks. Behaviors observed in the natural settings included landing, takeoff, feeding, and defensive charging.