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Duck Diseases: Wet feather

Wet Feather  is an occasional problem. 

Preening 
Ducks and geese need to keep their feathers in top condition to protect themselves against water-logging whilst swimming, and in wet weather. They normally do this by bathing to remove dirt from the feathers, and by combing the feathers through the bill. This maintenance of feathers is called ‘preening’. It includes the removal of parasites, the removal of scales which cover newly sprouting feathers, and also the spreading of oil over clean feathers. It also includes the combing of the barbs on the feather so that the barbules and even smaller hooks called barbicelli  interlock and form a protective layer to repel water..

The oil is obtained from the preen gland on the rump. This is an oily spot which can be found by searching near the drake’s curled feathers. The bird uses this patch to roll and stroke its head over the oil. The head is then rubbed over the body feathers to spread the oil evenly. This keeps the feathers bright and supple, and allows water to run off in droplets – as the proverbial ‘water off a duck’s back’

Some people believe that the oil of the preen gland has little to do with 'waterproofing' feathers, the main function of the oil being to keep the feathers supple. Freethy, in his excellent book 'How Birds Work', explains that preen gland oil is not the only defence against water-logging; constant attention to zipping the barbicelli of the feathers together is also important. However, one only has to look at ducklings to see that preen gland oil does have some function in repelling water. Ducklings reared under a mother duck have a certain extent of natural water-proofing from contact with her feathers. The contact maintains a good down structure as well as spreading preen-gland oil on ducklings when they are only a few days old. Ducklings reared without a mother are not nearly so waterproof. The debate about wet feather is not a new one. At some point, a review of earlier literature on the subject will be published by the CDA. 

What does wet-feather mean?
When things go wrong, a bird looks distinctly damp instead of glossy. The feathers become water-logged and unable to repel water. The outer contour and even flight feathers are affected. In a severe case, even the under-down may start to become affected. The bird becomes cold and miserable, and avoids water – which can then make the condition even worse.

This condition known as wet-feather is more common in wet winters. It has affected birds which have been free of this problem in the past. This has worried their owners too, because there often seems little one can do to help. Whilst the weather and environmental conditions in wet winters have undoubtedly caused the problem for many, I thought it might be useful, particularly for new keepers, to review several conditions which can cause this feather deterioration.

When wet feather strikes, there are several possible causes. In some cases, birds will not respond to the treatment given. In such cases the bird may be ill from another long-standing problem, and cannot be cured. 

1.Birds are kept with little water. They may look all right, but when they encounter wet conditions, the feathers immediately become water-logged and do not dry out easily. This may happen when a pair of birds are bought at a sale, and introduced to a place with plenty of water. This kind of wet-feather is usually temporary. In better conditions, the birds preen, oil up and re-condition their feathers in about a week.

2.The preen gland is not producing sufficient oil. This can be due to diet. Insufficient vitamins can definitely produce miserable birds. An example of this was when Call ducks were kept on a diet on hen-layers pellets only. They were mostly in poor, wet-feathered condition. The addition of 50% wheat to the diet helped the majority of the birds. Whole wheat provides vitamin E from the wheat germ. This is easily destroyed in milling. Whole wheat also contains vitamin B which waterfowl need. Supplements such as cod liver oil (on the food) and some maize in the feed in winter may also help alleviate the problem. Do try to feed pellets for waterfowl (not chickens) and make sure the food is in-date.

Hen layers pellets are poor food for birds which are not laying, and also for breeder birds. Maintenance pellets plus wheat are best outside the breeding season. A breeders ration containing the right amount of calcium for ducks, plus extra vitamin E and B for strong embryos, should be used in the breeding season. If birds are on genuine free range, they will pick up their own animal protein and greens, and it will probably not matter what they are fed as a supplement to their main wild diet.

3. The feathers get muddy. Once they have absorbed soil particles, condition is rapidly lost, and the birds find it very difficult to ‘oil up’ again, even if they have clean water.  Mud on the feathers probably strips off the oily protection. Muds contain clay minerals. Some of these clays have been used in the past in ‘fulling’ wool i.e. taking out excess oils. This may be what happens to the ducks. On the other hand, it could be the abrasive action of the mud which ruins the feather. Continuously wet conditions also exacerbate the problem. Affected birds simply cannot dry out, and cannot re-condition their feathers by preening. This is the commonest cause of wet-feather. A partial solution is to shelter the birds in excessively wet weather. They then have the opportunity to dry out. Allow then to swim on days when there is the possibility of them drying out - and keep the birds free of mud if possible. The growth of new feathers next season often cures the problem.

4. Feathers get dirty from moulds. Victoria Roberts, in her book ‘Diseases of Free Range Poultry’, cites soiling by plant spores and sooty mould from osier willows, which will continue to grow on feathers, as a possible cause of wet-feather on wildfowl pools. The recommendation is to wash the affected bird in detergent, preferably a shampoo designed for animal use. Care must be taken in returning washed birds to the pool. They need protection from cold, wet conditions until they have oiled up their feathers again.

5. Over-preening is also thought to cause wet-feather. This can result from a bird carrying a high parasite load. Common parasites on ducks include northern mite (a reddish-coloured mite which lives on the bird and sucks blood) and shaft lice which live on the feathers. Both of these parasites cause irritation. Preening of the shaft lice can start to cause shredding of the feathers. The barbules fail to interlock, and water-proofing is lost. To help the bird, parasites must be removed with an insecticide

• This can be in the form of a powder containing pyrethrum, or an aerosol. There are also organic powders such as Barrier, which contain essential oils which are good at zapping the parasites. These treatments are contact killers so the bird will need two treatments. Treatment 1 gets rid of the adult pests ; treatment 2 kills pests emerging from the eggs and maturing on day 7-8. Always use the spray or powder on a dry bird. Avoid spraying aerosol on the eyes. The propellant is an irritant. Follow appropriate withdrawal times. 

For further information on the use of veterinary medicines please contact your Vet or visit the website of the Veterinary Medicines Directorate www.vmd.gov.uk who are the regulatory authority for veterinary medicines in the UK.