My husband and I are having a disagreement about our new run. The fencers made an apron that is 15" out from the run, but did NOT dig a trench for it 1.5 feet down. We had a gopher (I think) tunnel in from several feet outside the run right into the run. I say our run is vulnerable. Another animal could do the same as the gopher, or use the gopher hole to come into the run. My husband says 'no way.' Who's right? Our first run has both an apron and is dug into a trench 1 foot down. We haven't had any problems with that in the time we've had it (over a year). We have had a "visitor" leaving scat recently. It looks like possum scat. Can they dig under? We have used hardware cloth throughout.
As long as nothing can get it's nose under the apron you should be fine. Use the long yard staples and use a lot of them to hold the apron or cover it with rocks. Rats will tunnel and they can be a problem but most other animals will just dig under and squeeze through
I think there is a limit to common sense on this. you could go down with a concrete foundation 36" and still worry about whether or not something can dig under. I have used the apron for years and have not had an issue.. Will something dig under there sometime? I hope not I dont think so but would a trench add double security yes it would but again I think the odds are very slim.
The key to an apron being successful is that many predators would see the birds and try to dig immediately at the fence, and be limited by the apron. They animals are in predator mode and don't stop to think to back up a foot or so and dig, they attempt to dig immediately at the fence and are blocked. That gopher dug under because his concetration was digging a tunnel, not eating chickens. I've known several people who have use aprons successfully. The apron just folds out ground level and they stake the apron down. And it's not a matter of animals not trying these people's defence, because one particular friend of mine who uses an apron, has SEEN the fox pace the fence at his coop. Granted, almost NOTHING can be completely predator proof. To be completely predator proof, you'd look like a kook and spend a TON of money on defenses. Because stop and think about it, you have hawks and raptors from above. Fox, coyotes, oppossums, skunks, bobcats, and dogs that are blocked by using a reasonable fence, like chainlink, or dogwire. But racoons and cats, can reach through wire, so to keep that from happening, you'll have to use solid fence or hardwire cloth. Weasels, minks, fishers, rats, and snakes, can get through holes that you can fit an egg into. Bears are pretty much unstoppable if truly determined. People and coons can undo latches, so padlocks would be in order. So in reality are your birds ever going to be "completely" safe? Not unless you have them in complete hardwire cages in a concrete bunker with a pack of terriers and LGDs on duty 24/7. Even then you'd have to worry about disease and cannabalism and whatnot. I know we'd like to be worry free with the predators, but the reality is, if you have chickens, you will more than likely suffer losses. Some people go years without losing a bird, but still it's more than likely going to happen. If I were you, I would be satisfied with just the apron. Stake it down so it can't be flipped up easily.
Thanks to all for your opinions. I think we will secure the apron all around the perimeters, rather than try to trench it now. We bring them in the coop at dusk every night, and only see the digging around the coop the next mornings.
You can eliminate a lot of burrowing (gophers, moles, voles, etc) by putting down human urine in the area where you do not want burrowers. Fill a 20 gallon hose end sprayer and apply to less than 2500 sq ft. Example - put a cup of human urine in a 5 gallon bucket and pour it along the edges of the coop. Since my coop is built on a slope, I pour from the uphill side and let the solution flow downhill. Eliminates burrowing alongside/beneath foundation blocks. Applied along a fence eliminates the burrowing that would otherwise naturally occur. If you see fresh mounds nearby, apply between the mounds and what you want to protect. For example, this is also the only way I have protected my fescue lawns while mounds form all around it. I spray a boundary 10' wide on the yard edges...100% successful after 15 years of use - knock on wood. Not saying this stops big predators but stops all the little critters. Must be applied a few tiimes a year. It does fade as time goes by.
Gophers will often tunnel under a run with a mind to accessing the feed room. The burrows can be 20-40 feet long and have more than one exit. I like gophers but they can be persistent! We use urine too- of all the native species they are most repulsed by it. Another solution is to floor your run with 1/2" gauge hardware cloth, latching it to the upper wire with pig nose rings. The cover with earth. A LOT of work, I would do it only if forced. This is what we did and we're been fortunate. Of course getting the birds in before dark and not letting them in the run until after sunset is helpful, too. https://www.backyardchickens.com/web/viewblog.php?id=7693-LynnePs_Run