Secret Species

There will be a branch of two points of view: Ylva and Kai. There are Animals, and then there are animals. The shapeshifters are called Animals, and the normal ones you would see anywhere else are animals.
Ylva Blomgren and her 'pack' are shapeshifters. Their main body is a Wolf, and they have names accordingly. Secondary Shift is a Bird of their choosing. They are granted Second Shift at age 15, and the bird they choose is permanent until age 50, when they can choose a different Second Shift Bird.
Uschi Beltz and her 'maul' are also shapeshifters. Their main body is a Bear, and they also have names accordingly. When they are born, they are given away to another tribe for them to care for. Secondary Shift is also a Bird of their choosing. They are granted Second Shift at age 12, and the bird they choose is permanent until age 45, when they can choose a different Second Shift Bird.
The toll for Shifting into a bird is usually tiredness/sluggishness for both species of 'shifter after they transform back into human. Both species can turn into a Wolf/Bear whenever, and for an unlimited amount of time, so it's not surprising if you see more Wolves/Bears than humans in their territory because it's more practical.
Kai Rask and the Roamers will be periodic in the story, and will meet a couple of the other characters. The Roamers do Shift, and they have Third Shifts. Due to the teachings of Itzal Abaroa and Simin Attar, they now have the ability to Shift into a Reptile of their choosing, and as many Reptiles as they want. The Third Shift isn't a permanent shift, and you can have a different Reptile each time you Shift.
There was a third tribe once, and they were the big cats. There was internal struggles, and most of the cats left and separated. Simin and Iztal were a mating pair that left together and saved a group of kids and a new mother from human hunters, and have been taking care of them since.