The beak and feather disease (BFD) is a viral infection affecting birds, particularly parrots, including corellas. Symptoms typically include abnormal feather growth, feather loss, and beak deformities. If you notice that the corella has such symptoms—along with a longer-than-usual beak—it could potentially indicate BFD. However, a long beak by itself doesn’t confirm the disease, as some individual birds naturally have larger beaks. To ascertain the cause of the long beak and any other concerning symptoms, it would be best to consult a veterinarian who specializes in avian health. They can provide a proper diagnosis and any necessary treatment. Additionally, be mindful that the presence of wild birds can spread diseases, and it’s wise to avoid direct contact to prevent further complications for both you and the bird.