A throne of swans - Katharine Corr

When her father dies just before her birthday, seventeen-year-old Aderyn
inherits the role of Protector of Atratys, a dominion in a kingdom
where nobles are able to transform at will into the bird that represents
their family bloodline. Aderyn's ancestral bird is a swan. But she has
not transformed for years, not since witnessing the death of her mother -
ripped apart by hawks that have supposedly been extinct since the
long-ago War of the Raptors.

With the benevolent shelter of her
mother and her father now lost, Aderyn is at the mercy of her brutal
uncle, the King, and his royal court. Driven by revenge and love, she
must venture into the malevolent heart of the Citadel in order to seek
the truth about the attack that so nearly destroyed her, to fight for
the only home she has ever known and for the land she has vowed to
protect.

Written in rich detail and evocative language, this is
the start of an irresistible, soaring duology about courage, broken
loyalties and fighting for your place in the world.