Dot Schwarz explains why Parrots moult.
Did you know that it is now assumed that some dinosaurs had feathers? This substantiates the view that birds evolved from prehistoric reptiles. Anyone who lives closely with pets like dogs, cats and birds knows that birds are NOT mammals in their physiology or their psychology.
And one of their striking differences is their feathers. Feathers dazzle us with their variety of shapes, colours and purpose. Each bird will have several types of feather; each species will have its own colours. Only the shape of a feather, no matter what size, has a shape basically similar to a boat or torpedo.
Feathers evolved from the scales (or possibly feathers) of reptiles. Birds being the only creatures (apart from angels and sadly I’ve never seen an angel) who enjoy feathered wings. Wing feathers are essential to allow the bird to fly.
Another purpose is a means of insulation, keeping bird warm or cool. You may see bird’s wings outstretched quivering slightly to produce a current of air. Birds unlike mammals have no sweat glands.
Male birds in the majority of species have more colourful feathers than the females. They use these for mating displays. Few of us have been to New Guinea but many of us will have seen shots of birds of paradise giving their mating displays.
Feather colours help us discriminate between different species of birds and, in some cases, between males and females. Birds with keener eyesight than ours see a wider range of colours. Feathers can be used as camouflage and protection from sun, wind, rain, and injury.
You may have noticed with different pet species, feathers are more or less water repellent.
The basic building block of feathers is keratin. Although human beings are different from birds, both species utilize the same protein; for birds in the feather sheath, for us in our hair and nails.
Every feather from the minute down on your Canary to the magnificent 30 cm long tail feather sported by my Benni my Macaw, has a central shaft. This fits into the feather follicle – technical name – calamus. Each feather is composed of filaments and they make the vane.
When a bird flies some filaments get displaced, so they’ll preen them and make them lie flat again.
Each feather consists of a tapering shaft bearing a flexible vane on either side. Look at a moulted feather and see that it is round and hollow. An opening at the bottom of the shaft allows blood to enter the young feather during its short growth period.
Once growth is finished, the feather is sealed off and, like our hair and nails is “dead.”
Types of feathers
Six types of feathers are contour, semiflumes, filoplumes, down, powder down and bristle.
The ones that we need to notice are contour, flight and down feathers. Contour feathers cover most of the bird’s body giving the characteristically smooth appearance.
Unlike your dog, you don’t have to brush your bird.
Flight feathers are the large feathers of the wing and tail. Flight feathers of the wing are separated into three groups.
The primaries attach to the metacarpal (wrist) and phalangeal (finger) bones at the far end of the wing and are responsible for forward thrust. There are usually 10 primaries.
The secondary’s attach to the ulna, a bone in the middle of the wing, and are necessary to supply “lift.” They are also used in courtship displays. There are usually 10-14 secondaries.
Most birds have 12 tail feathers. You can watch the Parrot use her tail feathers as a rudder or a brake when flying.
For whoever is cleaning cages, aviaries or bird rooms, (in some cases like our house, the living rooms as well) down feathers are a dratted nuisance. They get everywhere.
Downy feathers are small, soft, fluffy, and are found under the contour feathers. They are plumaceous, and have many non-interlocking barbs, lacking the barbules and hooklets seen in contour and flight feathers.
Down feathers trap air next to the skin, protecting the bird from heat and cold. They are so efficient that we use them for insulation, too, in down jackets and duvets. Fortunately for our pet birds, we take the down of ducks, hens and geese rather than Parrots.
Special types of downy feathers are called powder down feathers. Powder down can cause allergies for some carers. Using electric air filters or wearing a protective face mask are usually only partially successful strategies.
Down feathers produce a fine powder which the bird can spread over its feathers as a water-proofing agent. The powder also assists in cleaning as the bird preens.
The absence of powder down in birds such as Cockatoos and African Greys can be a sign of disease, including beak and feather disease.
Bristle feathers have a stiff shaft with only a few barbs at the base. They are usually found on the head (around the eyelids, nares, and mouth). They are believed to have both a sensory and protective function.
What looks like eyelashes in the hornbill are in fact bristle feathers.
The natural process for the gradual replacement of old, tattered, or damaged feathers with new feather growth is called moulting. A moult is usually triggered by the change in day length or may occur after breeding. I enjoy watching new feathers develop after the moult.
Tame Greys like Artha and Casper will let me scrape away the keratin sheath from the pin feathers round their heads. Looking after your own and your flock member’s new feathers is an essential behaviour for Parrots.
Bird will preen one another to remove old sheaths. Preening is a sign of a healthy bird. Ragged dirty plumage can be an early sign of ill health. Singly kept birds benefit from their owners preening new feathers in places they cannot reach themselves like back of the neck or top of the head.
Please be careful never to touch a blood feather; they are sensitive and the bird will complain or even bite if you touch one accidentally.
Like hair, feathers develop in a specialized area in the skin called a follicle. As a new feather develops, it has an artery and vein that extends up through the shaft and nourishes the feather. A feather at this stage is called a blood feather.
Due to the colour of the blood supply, the shaft of a blood feather will appear dark, whereas the shaft of an older, mature feather will be white. A blood feather starts out with a waxy keratin sheath that protects it while it grows.
When the feather is mature, the blood supply will recede and the waxy sheath will be removed by the bird. Although an adult bird will typically replace all of its feathers during a moult, the loss of feathers is staggered, weeks for smaller birds, up to several months for larger species.
Smaller birds can enter their first moult several weeks after fledging. Larger Parrots such as Amazons, Greys, and Cockatoos will begin their first moult at around 9 to 10 months of age.
When Benni at 8 months old, broke several tail feathers, I was delighted that he had started his first moult and they regrew within a few months. Most birds moult easily with no special problems. A few may have a somewhat scruffy appearance.
What you need to watch out for is if there are any bald spots or bare patches of skin. Inexperience can lead you to think that a bird is moulting when it is feather plucking.
Bald spots during moulting should be examined by an avian vet. The easiest way to know that your bird is moulting is to check for the appearance of pin feathers.
Nutrition during moulting
A bird renewing its feathers uses a lot of energy so at this time needs excellent nutrition. The bird needs a diet which enables her to produce protein for the new feathers.
An inadequate diet can result in colour dilution or stress bars on the feathers. With my own flock, I don’t ameliorate the environment or diet during a moult because I feel that the extra care due to moulting birds should be given all year round.
I asked well known avian vet Alan Jones for his view on PBFD and he told me
Definitely PBFD is widespread, both in captive Parrots and in wild native birds. Many birds remain symptomless carriers, and there is a very long incubation period before signs develop in birds that do get affected – hence the difficulty in controlling the spread of infection.
The virus took off in the UK when we had so many commercial breeding facilities that were mixing eggs or chicks from many different sources, and batch hand-rearing them before selling them on.
Certainly any bird with abnormal feathering should be tested for PBFD, and notable signs are abnormal feathers, with loss on the head. Plucked birds usually have normal head feathers.
Feathers come out symmetrically. You find a left wing feather on the cage floor and the right wing feather the next day. Some carers say that their birds can become ‘ornery’ during moulting. I have not found this to be the case.
But you do need to be vigilant in case the feather loss is due to a virus like PBFD and not either normal moulting or feather plucking. Young birds are more susceptible.
I hope to discuss feather plucking in a future blog. Read it here. My thanks to Bill Naylor and to Dr Alan Jones for allowing me to use his article ‘The Normal Moulting Process in birds. (1998)
Editors note: Here is a face mask that Dot Schwarz has made, using all the moulted feathers. It can be worn.