wild bird footprints imprinted in wet coarse grained sand

coarsegrained displacement environment footprints coastline footprint particles sediments undefined imprints tracking animalia chordata lutrinae behavior stepping wildlife mammalia feldspar animals closeup grained pressed pacific america aerial animal coarse shadow tracks weight digits quartz united states close print shore sunny track coast beach north gray grey sand view dual pair pads west paw sea waterfowl duck geese canadian webbing distinctive pattern design shape toes anatidae swans ugly duckling anseriformes anserinae anatinae identification skill education learning behavior