Exploring Shape Variance in Waterbirds' Pad Feet: A Geometric Morphometric Analysis

Waterbirds usually have webbed feet, which help them move easily through water. These pad feet fall into four main categories: palmate, semipalmate, totipalmate, and lobate. In this study, morphological diversity among the pad feet of different waterbird breeds such as the West Indian whistling duck (Anas bahamensis), mandarin duck (Aix galericulata), red-breasted goose (Branta ruficollis), wood duck (Aix sponsa), mute swan (Cygnus olor), greylag goose (Anser anser), mallard (Anas platyrhynchos), Pekin duck (Anas platyrhynchos domesticus), redhead duck (Aythya americana), Egyptian goose (Alopochen aegyptiaca), and pelican (Pelecanus onocrotalus) was examined by the geometric morphometric method. 2D images of 12 waterbirds' pad feet from different parts of Türkiye were analyzed from a dorsal view. In total thirteen landmarks were used. The analysis focused on principal component 1 and principal component 2 values. Principal component 1 shows slightly greater changes occurring on the lateral toes II and IV, as well as in the interdigital webbing below the average. Principal component 2 also reveals greater shape changes on the toes II and IV, which are more lateral. Geometric morphometric analysis proves valuable in identifying variations in the shape of the pad feet among various breeds of waterbirds, making it an effective tool for taxonomic purposes.