Where do plan on keeping them until they're too big? They'll be flying all over in about 2 weeks and pretty much anyone will tell you -you won't want them in the house any longer than 4 weeks, unless you love dust coating every surface in your home... no joke.
We have an empty two car garage I use for my new cats when they arrive. It's already insulated. I just need a few tweaks and it'll be perfect for chickens. It also has a back door that I've altered. It opens into a chicken wire tunnel that goes across the side of my house to a fully enclosed deck that's attached to the second story of my house. It also has a chicken wire gate and some small shelves, lots of dirt and bricks around the edges to keep from digging. When my new kitties arrive I let them play in there to get a feel for outside time and to interact with my other cats. It's no *huge*, but it will keep the chickens comfortable for now. I can even easily add some perches into it.
Your mom may have made a mistake by starting you on this adventure
Story time!
So six years ago I had five cats. We had just rehome 30 or so cats/kittens that adopted me from a field nearby (We had people dumping pets there a lot). Mom went into shock at just how MANY I was feeding. I mean, she knew, but then there's *knowing*. (It just kind of happened. They never came inside, and you only saw one or two at a time. They only showed up when they were hungry or in need of medical help.) She told me that I am NOT to have any more cats, no exceptions.
Then my brother's friend was going to abandon some kittens. I asked my mom if there was any way at all we could house them for a week pllleeeasseee??? She said yes, with the condition I adopt them out ASAP. They're still here to this day. (Horrible mites. Nobody wanted to adopt and then they were too old)
Mom again said NO MORE CATS. I agreed. My herd was full. Then my favorite kitty vanished a week before Halloween. Rough area, he was a black cat. I didn't need it pointed out to me what happened. Mom said I could adopt ONE more cat to help the healing process. I found a trailer park that was overrun and had neglected kittens. Picked one out from a photo, went to go get it. Mom fell in love with another while I caught mine. Two more furries added.
NO MORE KITTENS OKAY?!?! No problem, and YOU were the one that adopted the last one. Everything was fine until we came home one day. There were some kids across the street looking at a cat. Even from four houses away I was drawn to it. I KNEW I needed it. I went over and found he was starving. The vet said another two days and he'd be dead. He needed MASSIVE rehab work - no clue how to be a cat, super skitterish. I didn't even ask Mom, I just knew he was mine. She agreed. It was clear he belonged with me. BUT NO MORE CATS!!!
No problem! We move here, and my neighbor's wife died of cancer two weeks after the birth of their 3rd kid. The neighborhood helps babysit his kids so he can work. Mom said I'd help. A year before my baby of 17 years had passed, and I wasn't recovering. Everything was fine until the last two minutes. His son came in and let their 18 year old cat in. Our eyes locked and I went "Crap. That's mine." Turns out he hated cats, and it belonged to his wife. Painful reminder. He was actually trying to find a place that would put him down or adopt him. He's now my new special cat.
I MEAN IT THIS TIME. IF YOU ADOPT ANOTHER CAT I WILL KILL YOU!!! Fine, fine!!! I don't want one anyway! There's too many! It worked out until my brother showed up with a tiny kitten. He'd been adopted out WAY too young. The lady who adopted her couldn't keep him, gave him to a friend, who gave him to a friend, etc. He'd had five homes in 12 hours. My brother ended up with him and was desperate. So he asked if we could babysit.... Wolfie is still here two years later.
DO NOT LEAVE THIS HOUSE NO MORE CATS!!! I agreed! ... until my neighbor became homeless. Their sweet cat was going to be on the streets. They asked Mom if we could possibly take her. Mom said yes, and was super annoyed because I now have a rep for adopting everything. We're going to rehome her due to her not fitting in, but still. She's here for the winter.
(She said I could keep every single one of them, I'm NOT a hoarder. They have plenty of room, proper food, and all see a vet once a year. I'm really NOT getting any more cats. Mine are all aging. When they pass I intend to have no more than two.)
She gave up. She's decided to take the path of least resistance and give me chickens. At least chickens are less messy, easier to care for, and easier to let go when the time comes. I think her theory is if she keeps me supplied with babies then I'll stop adopting cats? Or the birds, or the lizard.
Luckily my husband understands my compulsion to rescue things and keeps me grounded. He was in on the chickens as well.