I was testing some late season lures last year and I had a hollow log that was 14-16 inch diameter I place the lure inside… red fox, grey fox, fisher and coyotes had no problem working the log even though they couldn’t see over it… i have tons of video showing this…. So does backing height really matter or that important?

Grey fox, it makes zero difference. For coyotes, the higher the backing, the farther from the backing your trap needs to be. Can't speak to the other varmints.

Yup, for coyotes is certainly does as Lazarus stated and I also have plenty of testing videos that substantiate that fact. If a softball-size clump of bunch grass is used the coyotes will step up close and then step over the clump and straddle it!

My most successful coyote sets have been up against backing at least 18 inches tall, sometimes more. I am not as experienced as many on here, but I haven't noticed tall backing being a problem. Short backings make it hard ( at least around here ) to predict where a coyote's going to step.

The wives tale that a coyote won't work a set with a large backing is a wives tale. Watch JC Conner's trapping videos.

I don't have a lot of experience I usually try to have as small as can get away with and not have them dig from the back side.it verys for me I've got away with rocks smaller than a baseball to a knot as big as a basketball.

Can you catch some coyotes with tall backing? Yes. Are there coyotes that tall backing makes them more nervous therefore harder to catch? Yes.

I've caught lots of coyotes on vertical field road cuts that were five to 20+ feet high and the set right tight to the base of the cut. I think, however, they are not as nervous at extremely tall backings like a vertical road cut as they are at a backing they can almost see over. Just my observation FWIW.

Agreed. When I set against a backing /Grass I try to trim any over hanging grass with scissors vertically ,.I don't trim it hard back but enough that if a coyote works the set the grass will not be hitting his face,.No issues so far.

Sure, the higher a given coyote population the higher the number of coyote with aggressive personalities that will work a tall backed-set vs the neophobic inclined ones, percentages stay the same, just more ! This means the trapper will have more chances of aggressive coyotes at a set. The higher the population the higher number chances an aggressive-personality coyote checks the set out.

It’s my experienced opinion that the higher the backing, the more novel the backing/object, divides the coyote’s attraction by personalities! If the coyote population was evenly divided aggressive/neophobic and you back your set with a tall backing, you, IMHO, are missing a large percentage of the neophobic coyotes vs a short backing. The short backing covers all the bases and includes the entire population regardless of personality!!

In my experience it doesn't matter until it does.

I've caught coyote tight to the base of big trees and had others tiptoe at a distance from a hat full of grass, go figure.

Generally, coyote minimal backing, grey fox big backing to keep them from working from the backside, red fox they're either going to dive right in regardless or not, coon/opossum don't matter.

Back in the early 2000’s I moved away from my Disco Dirthole set of the 70’s to try sets that at that time that had been made popular by those who were saying it to the greatest magnitude of the time! I found I really liked Miranda’s Double mouse hole fox set for coyote IN MY AREA so I used it in place og my Disco set. It was a set, at least made my way that caught all canines!!! Grey fox were mentioned previously, I would literally wipe an entire family of Greys out using that set in a few nights with the set made for coyotes . I always made that set with a low backing, a clump of bunch grass about 3” high. I didn’t give a rat’s butt if the canine came into the set over the backing or at a 45* angle or straight on, It was a set that didn’t miss with my guiding at the trap. I never saw how & why a low backing impacted the performance of the set until I began testing gland lures under a video camera.

Always use the video setting on your cameras people, still photos don’t not tell the story and leaves you either guessing or assuming but it all became perfectly clear under the video cameras!