Thursday, July 17, 2008

Accidental Loss of Tail Feathers

Posted: Thu Mar 27, 2008 3:34 pm Post subject:


I would like to add some further information to Jeffrey’s post on the accidental shedding of a tail feather.

Jeffrey and I have similar views on the keeping of shamas and I agree with his post. Like others, I have found him to be a storehouse of information and knowledge and his opinions always provide a valuation insight to any discussion on the problems encountered with keeping and maintaining the shama in captivity.

It is useful to have some background knowledge of the molting process to appreciate what is likely to happen when a shama accidentally sheds a primary feather.

Usually, the shama molts once each year as part of an annual molt cycle. The bird’s form should rise after each annual molt as it comes into breeding condition, followed by nesting and care of chicks and then a gradual deterioration in form as the bird approaches molt prior to the actual molt itself. The release of hormones in the bird’s body prior and during each stage in the cycle regulates what takes place in the bird’s physiology.

A shama that accidentally loses a primary feather sheds the feather outside the annual molt cycle. The hormone required for feather growth is therefore unlikely to be naturally present in the bird. The bird’s body will need to produce it if the lost feather is to re-grow. Whether or not this happens will depend partly on the importance of the feather to the bird’s survival. If the shed feather is from the wing, the bird may have lost an important feather that could adversely affect its ability for flight and survival. The loss of such a feather is therefore likely to trigger the rapid release of hormone to cause the lost feather to re-grow without waiting for the annual molt.

On the other hand, the loss of a primary tail feather is unlikely to be critical to the bird’s survival. Accordingly, there may not be a release of the hormone to cause the lost feather to re-grow until the next annual molt. If so, the replacement of the shed feather should take place together with all the other feathers.

Will the lost primary tail feather grow to the same length as the remaining primary tail? Assuming that the bird has had a good molt, the tails will have achieved their maximum length and the replaced feather outside the annual molt will unlikely be longer than the remaining primary tail. The exception to this is where the bird is very young and the tail feather is lost after the first molt. As is well known, the 2nd annual molt of a young shama should result in longer tails – perhaps as much as 20% longer than those after the first molt. In such a case, the replacement feather may be longer than the remaining tail feather on the bird.

Bearing in mind that the release of hormone regulates the growth of feathers, whether or not the new tail grows to the length of the remaining tail will largely depend on the period during which the hormone is released for the growth of the new tail. Usually, the release of hormone will stop before the new tail has reached its full potential growth. If so, it will be shorter than the remaining tail. Usually, the difference in length is 1 to 2 inches but it can be as much as 50%.

To ensure that the new feather grows to its maximum length, the nutrition and environment for the shama should be the same as that provided during its annual molt. Amongst other things, the bird should not be brought out to chai since this could result in an increase in testosterone which will counteract the hormone required for feather re-growth and will result in a shorter feather.

The difference in length between the primary tail feathers may continue even after the next molt. A primary tail feather that is shed and replaced outside the annual molt upsets the molt cycle for that feather. It will not have been on the bird for the usual length of time when the next molt arrives and may or may not shed. If it does not shed together with the remaining primary tail, there will again be a difference in length between the primary tails. Even if it sheds together with the remaining tail, the release of hormone for its re-growth may be for a shorter period and this will again have an effect on its length. It may take 1 or 2 molt cycles for the 2 primary tails to achieve the same length.

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