I don't know why people are worried about not letting their chickens free range. I live on a lake, and we have hawks and Bald Eagles overhead all the time. If I let my chickens free range, it would be free chicken lunch for the predators and I would be a former owner of a backyard flock in no time.
I built a nice chicken run, with bird netting on top to prevent aerial attacks, and my chickens are doing just fine. Over time, I converted my entire chicken run into a chicken run composting system, essentially bringing the free range to them in terms of grass clippings, leaves, garden weeds, etc... My chickens appear to be happy. They are certainly safe.
I converted my entire chicken run into a chicken run composting system. The compost is full of worms and bugs. My chickens spend all day outside scratching and pecking in the compost litter finding worms and bugs to eat. Not only do they enjoy that activity, but my commercial feed cost goes down by half in the summertime when the chickens are outside on the compost in the run.
I started off with a nice green grass chicken run. Then the chickens ate all the grass down to the dirt. I added a compost bin inside the chicken run, which was a big success. Over time, I converted my entire chicken run into a chicken run composting system. That has worked out best for me and my chickens.
I have not had any problems with composting in the chicken run. But, as I have said, over time I converted my entire chicken run into a chicken run composting system. It never smells, and I harvest hundreds of dollars worth of black gold compost for my garden every spring, summer, and fall. I tell people I have composting chickens and get eggs as a bonus.
I toss my kitchen scraps and leftovers into the chicken run in the morning when I let out my chickens. The kitchen scraps are usually gone within a few minutes, so there is nothing left to attract predators.
What the chickens don't eat, which is very little, just gets mixed into the compost litter to become bug and worm food. For example, I'll toss out watermelon rinds to the chickens. They will eat most of the flesh of the watermelon, but I will find a thin strip of the rind left at the end of the day. Same with bananas, they will eat the white part of the banana peel but leave the thin skin to get composted in the litter.
If I go out fishing and have fish guts from cleaning, I will also toss them into the chicken run. The chickens will peck away at the fish guts throughout the day. If there are any fish remains left at the end of the day, I will typically bury it into the compost litter in the run. I have never had any predator problems with burying fish in my compost. If I did, I would just remove the fish remains at the end of the day. Burying the fish remains in the compost just adds more good stuff for composting and the bugs and worms love to eat that kind of stuff. In any case, the fish remains automagically vanish in a few days inside the compost.
Chickens are omnivores, and I don't hesitate to toss leftover bits and pieces of meat into the chicken run. It all gets eaten in no time at all and I have never seen any meat left at the end of the day when I put my chickens into the coop for the night.
If you have an active composting system in the chicken run, then you really don't need any other distractions for the chickens. My chickens are active all day scratching and pecking in the compost litter, creating compost for the garden in the process. It's a great system, my chickens appear to be happy, and I get lots of compost and eggs.