Moonlit Flight

This is a world where due to human radiation (most humans died out), some chicks are being hatched mutated. Parent owls usually kill or abandon eggs that are mutated, in fear of what they will become - most of these chicks are born dead or mutated too much anyway. Mutation can be easily recognized - birds have bright markings on their feathers and something is different about them - whether they have extra limbs/feathers or they are missing something. Sometimes they can have different senses, dulled or sharper.
In a world like this, there are some good birds too - like Helen, who looks for abandoned eggs and hatches+raises them on her own.
The world is divided - a magical crystal has been stolen and it can wreck chaos in the wrong talons.
Four different owls - Serenna, Ferk, Allistor and Amari set to search for the crystal - do they want the crystal for themselves or do they want to help? No one knows, maybe not event them. They encounter old and new friends on their journey, learn a lot and grow.