Eyes and ears. Upon arriving at a site I take a few tentative steps into/onto it and stop. I scan for movement of any kind ... birds already spooked and therefore in flight, twitching of leaves that is too severe, or too isolated to be attributed to the wind, and I listen for sounds. Some birds barely make a noise. Staines pond is next to a busy street so there is a lot of city racket to contend with, especially trucks and motorcycles. When I do proceed I may only walk a few meters before stopping and look and listen again. Rinse and repeat. Animals proceed in increments while humans give away their species by trudging along like they're part of a parade, without stopping.