Bored chickens (and chicks) can resort to such things as eye pecking, feather picking, and other habits that are hard to break. Objects added to their environment are not a matter of "entertainment" for you, or aimed at creating brilliantly minded chickens. Look at it this way. If those chicks were out with Mama Hen, what would they be doing? Would they be restricted in their movements by the sides of a box? Would they simply sit around waiting for the food dish to get filled? And would they sit in a neat little row like quiet little stuffed chicks just being adorable?
Nope. They'd be running all around the coop, the run, and/or the great outdoors. They'd be watching the adults, most especially Mama, seeing how she scratches in the dirt for little tidbits and copying that behavior, finding tidbits of their own. They'd find rocks to investigate, experience different surfaces, and just dash under her for a quick warm up or a little security if they got spooked. So putting in things for them to do is actually a very healthy, important part of them learning to be chickens! Their days are filled with new experiences, adventures and learning. So encourage that! Without that you just have a box of chicks.
When I got my first chicks, I did the heat-lamp-box thing. The first day they arrived, I put them in their brooder and then came here to BYC to see if I'd missed anything as far as their care was concerned. Yep, I had. I hadn't put marbles in their waterer to prevent drowning. So I ran out, bought a bag of big marbles, and was putting them into the water when I dropped a couple on the floor of the brooder. They ran to the opposite corner like their tail down was on fire. Then a couple came back over and tapped the dropped marbles. The marbles moved. Those chicks were suddenly engaged in their impromptu soccer game and the two chicks that I thought were "aggressive" - pecking at the others' eyes and beaks - were now focused on the game instead.
I have never forgotten that lesson. One of the long roosts in their run swings. They love it. I hang those wire suet feeders in their run from time to time - not all the time, but just enough so they are immediately drawn to them. During those long, cold, dark days of winter when they are more confined, they are great boredom busters - I fill them with homemade or commercially bought suet as a little extra protein and fat in their diet, but they have to work to get it out. I also stuff it with kale, or chopped apples - whatever I can cram in there. It''s good for them and keeps them too busy to start taking their boredom out on each other. In summer I stuff them as full as possible with melon chunks, frozen fruits and/or veggies, and they love it. I've even frozen water in the little plastic holders that commercial suet comes in and put one in each hanger. Sure cools them off, and they like to stand under the drips as it melts. I have a huge half log from a dead tree in there. It's hollow on the underside. It's a lifesaver in the run. The older birds climb all over it, searching for little spiders or scratch that got tossed in and maybe missed the first time. The little chicks have a place to hide if the older birds get a little bossy. (I raise my chicks outdoors in the run now, in a pen, and they are fully integrated with the older chickens by 4 weeks old). Every so often we flip the log over and they all scour every inch of the hollow, finding all kinds of little bugs.
Am I spoiling my chickens? Nope. I'm encouraging them to BE chickens. Since I'm the "mom", I'm teaching. They are learning. We all win, and bad behavior brought on by boredom in not an issue.
Edited to add: I neglected to mention another thing that I do with all my chicks. I toss a big clump of sod - dirt, roots, grass and all - into their brooder or pen. They love it! They dig, peck and scratch in it until they have it broken down into a pile of loose dirt. They get small particles of grit this way, they are exposed to a bit of what they'll be living on to help build up natural immunities, and dust bathe in what they've knocked off the clump.
When did you start giving them treats and toys?
I want to spoil my chicks and let them have fun😉
How old were they when you gave them the clump of dirt/sod, love that idea!