Applications of Photogrammetry to Neoichnological Studies: The Significance of Shorebird Trackway Distributions at the Bay of Fundy

Abstract

Low-level drone photogrammetry is a technique that allows for the construction of surface orthomosaics and elevation models. Despite being used for a wide range of geological applications, these types of datasets have not yet been explored from a neoichnological perspective. This study uses three examples of tidal flats from the Bay of Fundy to demonstrate the usefulness of 3D photogrammetry in the collection of high-resolution neoichnological datasets. The first site is a bar top along the Petitcodiac River that is situated between a salt marsh and tidal channel margin. The second site, which is located along the Shepody River, represents a laterally accreting channel margin and thus has a relatively high relief. In contrast, the final site comprises a gently sloping tidal flat that is far from the influence of a major tidal channel. Spatial analysis of the shorebird tracks at each site was used to assess the relationship between shorebird track distributions (e.g., track density, stride orientation, stride length) and various environmental and ecological factors (e.g., topography, tidal current direction, invertebrate prey distributions). Additionally, morphological analysis of the tracks was used to assess variations in substrate cohesiveness, which is the environmental factor that exhibited the most variability at the study locations. The track record at each site represents a shorebird flock that traversed the tidal flats in such a way as to optimize foraging success. As a result, the abundance and availability of macrobenthic invertebrate prey was the primary factor contributing to shorebird track density. This paper aims to assess local-scale variations in tidal flat substrate cohesiveness and provide context for the interpretation of fossilized shorebird trackways.