A female nestling Goshawk with aberrant feather development, especially in the rectrices and remiges, is described. The flighl feathers were malformed, ragged (looking ’moth-eaten') and full of faultbars (photo); body feathers and coverts were not affected, apart from being heavily faultbarred. The bird had lesions on the ulnae, close to the carpal joint, which were only revealed after dissection. The remnants of flight feathers were loosely attached in the follicles and rectrices were almost absent. Her three sisters had a normal plumage development. There were no indications of food stress (except for the faultbars) because the weight gain was normal in all four nestlings, nor of the presence of Mallophaga.