I have a question; I read a lot of posts about folks saying animals such as raccoons can rip right through chicken wire which I do not dispute. My question is, if you already have 2” x 4” hard wire in addition to chicken wire why add more hard wire? I don’t know of any chicken that is going to stay next to a fence while a raccoon rips it apart piece by piece, & any animal that can rip through chicken wire certainly can’t fit through a 2” x 4” hard wire opening, it would be too large, like a raccoon. I have chicken wire in some coops not to keep predators out but to keep scavengers like hosps away from the chicken feed. It just seems to me that a lot of folks are going through an awful lot of expense without justification. Please explain.
Why would some people add even more wire if you have 2x4 and chicken wire? I did not, and the chicken wire was only around the bottom 18" or so. That chicken wire was mainly to keep baby chicks in, not to keep critters from reaching through. But a lot depends on your philosophy. My basic philosophy is to provide a highly predator resistant run during the daytime and a pretty darn predator proof coop at night when predators are more active and the chickens are asleep.
While practically any predator can and sometimes do hunt during the day they are most dangerous at night. Some are a lot more active at night. Even the ones that regularly hunt during the daytime like coyotes, foxes, and bobcats are more likely to stay away because of human activity during the day. I once trapped a raccoon at lunchtime and saw a possum feasting at my compost heap at 1:00 in the afternoon. Even those critters are out during the day, but a predator resistant run during the day and a highly predator proof coop at night works for me.
With a combination of 2x4 and chicken wire certain critters can still get through: snakes big enough to eat eggs or baby chicks, mice, rats, and weasels for example. Some people are trying to fence those out of the run. With the pop door open these can enter the coop if they make it into the run. 2x4 wire by itself or even with chicken wire added won't keep everything out.
The biggest risk of a chicken being attacked by a raccoon reaching through is at night if the chicken is sleeping within reach of the fence. Nighttime is the biggest risk if your chickens sleep in the run. Some people leave the pop door open at night, especially if they have a tiny coop and their chickens need the room when they wake up. But chickens are not always the brightest when it comes to protecting themselves. They can get complacent if the predator is patient. All it takes is for the raccoon to get a good hold and the chicken cannot get away. Does that happen very often? Not really but some people are convinced that if anything can possibly happen it will, however remote the chances. And it can possibly happen.
When a lot of people build their first coop, they often don't realize how many potential predators they have, even in the middle of suburbia. A lot of times they want to retrofit the coop to make it safer once they realize what they did to know. It may take finding just one snake in the run to convince them they want to do something different. Or reading one story on here.
A lot of the people active on this forum are people just starting out with chickens. They have no experience and are on here to learn. It is a good place to learn. Without that experience they tend to believe everything they read on here, no matter how outlandish. To a large extent they want people to just tell them what to do, not explain why they should consider doing it. That's human nature, especially if you are not familiar with the topic. For their own legitimate reasons some people are willing to spare no expense in making sure their chickens are as safe as they can possibly be. I have no problems with that, they are doing what is right for themselves. Some of us are more risk tolerant. Just because I'm quite happy and so far successful with a 2x4 run with chicken wire around the bottom and as the apron does not mean it is the right way for everyone.
I think there are many reasons someone might want to retrofit a smaller mesh wire to an existing run. I don't think it is required for everyone, it is a decision people need to make for themselves.