LCB: I have a small hand held, battery powered UV light that I have used on old roads and trails to see what was using them, but you are apparently wanting to cover much more ground than that. Portable UV lights are now much cheaper than when mine was bought and hunters use them to follow animal blood trails after dark. Police have used them for years. As Hiflier mentioned flour would show tracks, but rain or dew would mess it up outside.
If you care to check limited areas for track, you might try this option. Get a UV light, a "professional" (that's the way they are labeled" hand held spray bottle, fill it with canola oil and spray the area you want to monitor with it. Check the area later - several days or more - at night with the UV light. The oil is fluorescent and you will be able to see the outline of animals' feet that walked over it. The oil will adhere to the feet of soft soled animals and the fluorescent material can be seen past the treated area.
There are other dry or liquid materials you could use that fluoresce - gypsum, talc, calcite or laundry detergent - but rain would wash if off sooner that it would the oil.
Disclaimer: Personal use of this procedure has so far confirmed what I knew before hand; there are bear, coyotes, cougar, raccoon, deer hogs and people who walked the trails and old roads. Your results might vary.