Abstract

A new experimental setup using a collapsible wooden tray, monopod, and digital video camera is used to observe and collect modern bird tracks. This setup is unique because it simultaneously captures tracemaker behavior, trace morphology, and media consistency (i.e., grain size and moisture content), and can be used in the laboratory and in natural environments. Here we provide examples produced by domestic chickens (Gallus gallus). Using this setup we determined that bird track morphology varies in a predictable manner with respect to sediment grain size and the percent of water present. The finer the sediment grain size, the more detail is likely to be preserved. If the sediment is completely dry, no track details will be preserved––digit impressions will be broad and will not taper at the tips; digit impression length will be longer than the actual digit lengths. If the sediment is wet (8.8%–6.7%), digit impressions will taper to points, will not be as wide as in dry sediment, and will not preserve pad impressions. If the sediment is variably moist (5.3%–3.2%), the detail level of pad or scale impressions, depending on the grain size, may be present. Within this study, we propose a sinuosity index that allows for quantification of sinuous avian trackways, and quantify the trackway parameters of behaviors, including start-stop walking, walking, running, takeoff, and landing. Both takeoff and landing traces are significantly deeper than the proceeding or following walking and running traces. Start-stop walking does not always result in side-by-side paired tracks, and often the bird will pause in midstride. Linking behavior and morphology of tracks can be used to better interpret ancient behavior and the depositional environment in which ancient tracks were produced.

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