By Dr. Colin Walker BSc, BVSc, MRCVS, MACVSc(Avian health)
Birds with feather changes are commonly presented to veterinarians for examination. One of the reasons for this is that changes are so readily visible. Often, the early symptoms of ill health can be hard to detect in birds because of their ‘preservation reflex’ (where birds that look different stand out from the others and are therefore more vulnerable to predation). It is therefore not uncommon for birds with advanced disease to be presented very late in the course of the problem with a history of being visibly unwell for only the last 1 to 2 days. This is not the case with abnormalities of the feathers – the changes are there ‘in your face’ with even early minor changes being readily visible. So how can feathers change colour and structure once they have grown? Essentially this can happen in one of four ways. Feathers can change their appearance due to:-
This Eclectus hen has experienced a transient health problem that has interfered with feather growth leading to ‘fret’ mark formation which shows as yellow banding on her feathers.
Left and middle – ‘Red’ Princess parrots. Right – A feather from the bird in previous photo, showing abnormal red banding across the vane of the feather.
‘Gold’ cockatiel. Blood tests showed this bird to have a fatty liver and diabetes. Right and middle photos were taken approximately 5 months after Left photo , following the bird’s successful treatment. The bird is changing back into a normal colour during its moult.
13 year old Lovebird with replacement of normal green feathers with yellow feathers. Blood tests showed this bird to have a fatty liver and high cholesterol reading due to being offered only a dry seed diet.
Left – In this Eclectus male, some green feathers have been replaced with yellow feathers. Only veterinary testing will reveal the cause of this but either systemic disease or an agent that has inflamed the feather follicles while these feathers were growing are possible causes.
Right – Pink wash through the wing covert feathers of a galah with hypothyroidism.
Young Alexandrine parrot. A mutation or not? This birds feathers display atypical colours but are also structurally abnormal. Only a review of the bird’s history and testing will show whether these changes have a medical or genetic basis.
As a veterinarian it is always interesting to see what type of plumage people regard as normal. Some aviculturalists can come to regard the slightly dry feathers and faded colours of a bird that is not 100% healthy, or on a less than optimal diet, as normal. It’s only when birds are seen whose meals are based on a complete formulated diet and that are managed well in a good aviary environment that one realizes just how vibrant some species can be.