They sure are a handful. XD
There is mention of a breeding season in chapter 2, page 13. Not that it says anything specific.
I'm very curious about how that will go now that they have access to non Ostrish beastkin. After all, we can see that they have shown interest in non-Ostrish and since it seems that breeding between humanoids is possible in certain cases, we may see a generation of half-Ostrish beastkin that have bigger brains and are actually capable of functioning somewhat in human society.
I mean, we've seen that orcs are considered to be non-linguistic humanoid monsters, but Ostrish beastkin are only a tiny step up from that. They're also ravenous, have a short fuse and no understanding of law, which means that theft and murder are just not concepts they have and if they meet anyone who threatens them in any way, they are likely to kill them.
So yeah, they're cute and all, but I wouldn't be surprised if they were categorised as pests.
MC developing intelligence is something that is unlikely to ever be replicated in another Ostrish beastkin and I know that's a good way off (and basically not in scope of this manga), but once MC is gone I really wonder how these Ostrish beastkin will ever survive in human society. So if they can breed half-Ostrich beastkin with a brain, that would really help the MC in managing that flock.
Well, for now, we'll just have to see how they avoid letting these cute murderchickens get in trouble.