The Thief Who Sang Storms by Anderson Sophie

The Island of Morovia is shaped like a broken heart. The humans live on one side of the island, and the alkonosts – the bird-people – live on the other. But it wasn’t always this way. Linnet wishes she could sing magic, like her father, Nightingale – and bring the two sides of her island together again. For her land has been divided by a terrible tragedy, and Linnet has been banished with her father to the deepest swamps, leaving behind her best friends, Hero and Silver. So when her father is captured, Linnet must be brave and embark on a treacherous journey. Through alligator pools and sinking sands, she finds new friends. Yet without her singing magic, Linnet discovers something even more powerful. Something that could save her father, and heal the broken heart of her island once more.