Do you have access to a trail camera or two? They take pictures whenever something walks by. I have 4 of them and find them extremely useful I need to know who or what is coming around. They take pics day or night. All these pics were taken by the same camera in the last week or so - I think I found a predator highway! You can get a good camera for around $100.
What kind of game cam did you use? How good is their performance (meaning: how often do they brake? LOL).