It's rare in many aspects. Light hearted, but somewhat dark due to a lot of the flashbacks having involved the various small borbs getting killed in various ways.
But also, Reincarnations where the MC is some variety of Monster Girl, especially that is more than just a person with animal ears is very rare. Somehow good ones of those are more rare than ones where they're reincarnated as some inanimate object like a sword, vending machine, or book to name a couple.
They aren't baby ostriches but rather normal ostriches. The MC is an evolved ostrich not an adult ostrich. There was some other ostriches in the pack that are older than her.
I was going to make the same point. The male and female "little ones" are indistinguishable. The MC mentioned in passing that some of the "little ones" get busy humping away making babies when there's enough food and safety.