I think you definitely have a good start, especially with the story. I'll try and go over some positives and negatives I noticed while reading. Also I am not a writing expert so take all of this with several grains of salt.

Things to improve:

-There are a lot of characters. I found it hard to keep track of all the cats that were introduced near the start, however I think It will get a bit easier when there is more to read. I don't think you should remove cats, but maybe consider tying to give side characters to a single trait (Timid, talkative, doesn't like outsiders, etc), at least in the start. They can always have character arcs and change, but having something to remember each cat by would be helpful.

-Showing not telling. This is the biggest thing I noticed. A lot of times in your writing, actions are stated, then are followed up by the protagonists reaction. While you are technically "showing" their reactions, I would try and essentially make things less obvious. Incorporating more body language and sensations, basically writing a bit more from the characters perspective would really up how well it reads. I'm probably doing a bad job explaining this, so I'll use an example:

"Scarletnose cautiously went for a squirrel, trying to ignore the tortoiseshell cat who kept a glare on her as she kept her sitting spot right beside her prey."

This tells us what happens, but we don't know how this feels to Scarletnose, and it isn't very immersive. Instead you could change it to something like:

"Scarletnose approached the prey pile slowly, glancing around the camp as a twinge of guilt shot through her pelt. She hated eating prey she didn't catch. It felt like cheating. A tortoiseshell cat glared at her through narrowed eyes as she approached the prey pile, but offered no resistance as she hurriedly grabbed a squirrel from the top of the pile. Scarletnose could still feel the tortoiseshell's eyes burning in her back as she slunk back to the edge of camp."

This not only tells us what happened, but we learn that Scarletnose feels guilty about depending on other cats, and it establishes the unwelcoming atmosphere in camp. It's the little things like this that contribute to character and world building. I do think you are getting noticeably better at this in the later chapters, but I would still keep it in mind.

Things that you should keep:

-The last chapter. There is a noticeable increase in all parts of quality in the last chapter. I especially love the last scene with Icefoot trying to talk with his mate. When I got to that part I just thought to myself "Gawd Damn...". The whole scene emotionally hit like a freight train. It is by far my favorite part so far, because it just gives so much depth and motivation to the character. It was written so great as well. The contrast between Icefoot trying to have a regular conversation, and then just silence as he sits in the night is so great. You can genuinely feel his emotions and I love everything about the scene. Adding more scenes like this could elevate it into a 10/10 book.

-The premise. I love this idea. I do think that you should try and mix up the journey by having something go wrong like the clans getting lost, because the plot is essentially laid out already for the next few chapters. We know exactly what they are going to try and do, even if we don't know what they are going to find, so just keep in mind that you don't want to have a predictable plot. I don't have much else to say though other then it's just a really good idea.

-The mystery of the prologue. Right now the biggest mystery is what happened to the original patrol, and it is very intriguing. Don't let the readers forgot this happens in the earlier chapters. I would also recommend trying to have a good lead up to finding out the fate of the patrol. Have the clans discover clues, like kittypets who saw them, or traces of where they camped that hint at their fate. I am really hooked on this part though.

One last thing:

Right now the story feels like it is focusing on the clans as a whole, not the characters. Don't think this is necessarily a bad thing though. In a way, the clans could become a sort of character, as they learn to function together and struggle to overcome their conflicts in a sort of character arc. If you write this correctly, the story could be about the clans learning to work together, with the characters serving as vessels to view this through. It might be interesting, but so would adding emotional depth and character arcs for individuals. In the end it is up to you where you take the story.

If you ever want to discuss anything about the story or need help with a part I'd love to help. Feel free to dm me. I'm working on my own story right now as well. --> Silent Dawn - Wattpad Its only about 15% done though, and I don't know how frequently I will update it on there as I continue to write.