HELP!!! Rescued chicks!

Hi I live in the USVI and found 4 baby chicks curled around their dead mother on the trail leading to my house. It's looks like she got caught up in something and crushed her wind pipe, and then suffocated. I think their about 3 weeks. And judging by the cute little tails they have, 3 female and 1 male. I don't have the heart to vent sex them cuz they were wild. We have chickens every where here cuz there aren't any natural predators, besides the roosters who will kill an unprotected baby male. Im trying to figure out what things I should do to help them prepare to go back into the wild once they're older. Also can anyone determine how old they are & what breed they are by that picture? (and if y'all can see those baby tails does that mean I'm right and they're female). I was just guessing age based off pictures I found online. Also why are 2 more yellow, and the other 2 darker? Also any suggestions on what to feed them? The guy at the store said that regular chicken feed, that i put in warm water to break it down for them is a good start, along with bread and ive tried cooked carrots(they dont seem to like em, but i read they may like em better once the carrots start to go bad) but what else can i feed the little peepers??? And any other suggestions y'all have would be a great help! They're pretty comfortable around me for the most part, especially In the mornings and night. I have them in a big planter box with just regular dirt from the yard(they like to scratch, peck and eat random bugs they find) with leaves for litter. They sleep in a regular box with a rug on top(they can get outta their bed box. its next to my bed, and I wrap them In old shirts cuz surprisingly it does get cold here at night(below 75 degrees) and they were used to sleeping curled round their mama. Even i wake up cold in the mornings and im under blankets! I haven't named em either, lol, any suggestions? Pretty much just looking for any advice y'all may have on upkeep and raising them!!!! Thanks!!

 

Thank you everyone, I'm not sure what the calcium content is in this feed. Their wasnt a label. down here they buy in bulk then re-bag it @ the store, but I can find out though. As for the grit, I've noticed them eating the little tiny tiny stones in the dirt so I think they have that one covered. & All the dirt here has sand content in it all ready, which they do peck at it all the time. (im assuming that their eating a little dirt every time with the little things they find.) A few local chicken raisers told me that if they were wild, and are around 3-4 weeks then the mother has taught them the basics all ready. I just have to make sure they can get what they need. What kind of greens? I noticed them eating these little fern like leaves? Should I pick some of them and cut em up for them? Also my room doesn't just get to 75, thats outside temp, it drops to around 60 in my room, sometimes even lower. i noticed they were cold that first morning, which is why i added an extra shirt. My apartment is like a little cave. I only have the two windows in my entire apartment. So I set them in the kitchen once theyre awake, which in the afternoon gets direct sunlight. Ill pick up some plain yogurt for them this afternoon, I would rather not buy them greens cuz they're most likely sprayed with stuff! Today my goal is to get them some exercise, I let em run around my bathroom in the morning. And then work on balance. LoL I need to find a stick, reasonable thickness and long enough that I could wedge it into their play pen for them to jump onto. (Maybe ill try hitting up the hardware store for a dowlrod, but they're only open till 430) They were attempting to balance on the side of the box when I woke em up. Yes, I have their time schedule more in line with mine. They kinda adjusted to mine that first night cuz I didn't get em till almost 730pm and took awhile for them to calm down and go to sleep. Their mother was still warm so I'm guessing they were only alone for about an hour or two. I put em to bed around 8-9 and they wake me up around 10-1030, though they slept late this morning, were still sleeping when I woke up at 11. And they are SOOO fricken cute when they're sleeping! The one also seems to be bonding with me hardcore, is that ok? When I do release, it will just be into the yard. At night she wants held while she falls asleep then after I put her back in the box. I can tell them apart now, and they definitely have their own personalities. I've tried looking at their wing feathers to determine sex, but as I'm pretty sure 3 are female it's hard to tell the difference between them and the male. There was also a baby that got away, I have not heard him peeping so I hope he's ok on his own, and that he didn't get attacked. I've heard stories of mongooses eating everything from baby kittens to baby chicks down here. Ps. I live in Cruz bay, St John UsVi!

 

Finally got the pictures the load for y'all! See the next page for pics of my little peepers!!! ps. My cat seems to dig em! He licked the one, nudged another back to his sisters and even adjusted their food thingy around with his paw! (Which was absolutely adorable) And he has huge claws so if wanted to damage he could. I'm thinking pictures of peepers riding my kitty will be coming shortly!!! Haha! Thanks again for any advice y'all have!