"A Whisper of Wings" is not a genre novel. It is a novel about ecological disaster, social rebirth and passionate characters that is told in a 'fantastic' setting. It is not a 'fantasy' novel.
Why say this? Because the rigid, stifling genrefication of literature forced on us by the publishing houses over the last decade has made strict boundaries. "Fantasy" is now defined as being crypto-medieval. It has magic, humans, pine forests, swords and bar maids. (We call it the CFU, or "Consensus Fantasy Universe". More colloquially, it is known as "NAFF" fiction: "Not Another F*cking Fantasy!") In essence, CFU stories remain within the paradigms set by Prof Tolkien and Robert E Howard.
The CFU is to literature what the invention of panty hose was to heavy petting...
"Whisper" creates a unique environment to meet the movement and themes of its story. The setting creates an internal logic. I suppose this therefore means the book is a 'non genre' fantasy fiction.