I have to premise this by saying I don't set a trap for coyotes until the last week in November or around December 1st. So the soil and weather conditions can really vary from then until the last of February when I pull them. When I set a coyote trap I expect it to function during tough weather conditions and have a catch. Why do folks use material that will absorb and/or hold water (then have the potential to freeze)? Paper towels, coffee filters, fiberglass insulation, even pillow batting have all proved (to me) that in wet, freeze/thaw soil conditions that they are not dependable. IN early fall, warm weather or little moisture areas where the soil does not wick H2O into those materials it will work, but not here. The only item not susceptible to ice/rock hard formation (in our climate) around or under the pan is AIR. A void under any dog or dogless pan is the only dependable "undercover medium" I want. You can use synthetic covers to drape over the pan (Latex, nitril, nylon, plastic bag(s), etc.), use synthetics under the pan or use some natural material under or over the pan (grass/vegetation, wax paper, screen above and sawdust, peat moss etc. below) to fill space or get the void. I am prone to use natural material that is inexpensive, needs no retrieval after the trap is pulled and has little or NO prep time so its wax paper rolls, cut, folded and placed outside a few days before use for me. Have caught coyotes, coons, fox, mink, dogs and feral cats in traps that were set and received rain, freeze, snow, thaw, refreeze, thaw, re-refreeze, rain, freeze during and through more cycles than I can count with wax paper. I have caught coyotes consistently with no trap bed care 60 days after such a period using AIR as the substance under the trap pan with both wax paper and trimmed plastic bag covers. Wax paper wins in the long run for me. ..........................the mike