siberian ruddy crake leg prints on silt

track trace trail mark footprint scent leg prints mud bank bird feeding siberian ruddy crake rail porzana wader wading species silt clay ooze slob sullage oozes sludge alluvium pulp river delta creek entry estuary firth lade billabong debouchment gullet rivers mouth outfall secretive birds swamp marsh bog quagmire morass backwater