Honestly I imagine she's more of hybrid... maybe her feathers just never grown in =p
With heavy human bones she'll never be able to fly anyhow. Not to say Rex's kind actually can fly...
But truthfully, no cloaking device could truly take on the illusion of a full human. Rex is still lighter than he should be and not as durable as a human. And some other things I probably just haven't thought up yet...

I like Nick's TMNT by the way, it's cute and more recently... rather badass and tragic.