Thursday, July 3, 2008

Stress Molt

David: I have a Mongolian skylark that I've kept for about a year now;after I bought it , the moult started very soon and fast; fully molted within a month, beautiful new feathers came out and the bird started its loud song and display; everthing was good for a while; then the bird started to moult on and off for quite a few months now. The bird was quite healthy and eats well ; is it stress ,nutrition or some other unknown factors( to me anyways) that would cause a seeming very healthy bird to moult on a continous basis??? I have gone into your new blog and read the 3 articles on moulting already ; any advice from you would be much appreciated. By the way, your blog is extremely useful; not only for shamas but the knowledge should be transferrable to other song bird species.

As you know, a healthy bird should naturally molt only once each year. This molt will be part of the bird's annual cycle of molt, rise in testosterone as the bird enters its breeding condition, building the nest and defending the nest site, rearing the young, repairing the nest and raising another nest of young and so on until the bird again starts its annual molt.

If the bird molts outside the scheduled time, the bird has a stress molt. This is also known as French molt. This molt may be a light partial molt where only a few breast feathers fall, a more serious partial molt where some wing and tail feathers are shed, or, in extreme cases, a full molt.

Obviously, a full stress molt is the worst thing that can happen to the bird. The feathers comprise about 20% to 25% of the weight of the bird and their replacement out of season means that the body has to cope with an unexpected demand on its resources. Further, the demands of a molt mean that the hormone testosterone is reduced and it is replaced by the hormone that induces molt. It can be seen therefore, that an out of season molt can upset the entire hormonal balance of the bird for the year. Consequently, it is not surprising that birds that have stress molts are seldom able to rise to their full form for the year. Often, the bird's form will only be able to return to normal only after the next molt.

Now as to the possible causes of stress molts - there are many. It may help if I just list them and you can see if any applies to your case.

1. Is it possible that the bird may have been frightened by a rat, lizard, cockroach or other creature, at night. To ensure that this does not happen, I have a small light at night as the bird tends to panic if it hears noises but cannot see the cause.

2. Is the bird subject to variable temperature in its surroundings. Keeping the bird on and off in an air-conditioned place will induce molt. Molt will also be induced if a bird that has been kept indoors for a long period is then housed out-doors.

3. The close presence of other birds of the same species causes stresss.

4. Inappropriate drinking water can cause constant feather loss with some species being more subject to this problem than others. The Oriental White-eye, for instance, is very susceptible to the quality of its drinking water. For this reason, I do not use water straight from the tap as drinking water for my birds but let it stand for at least 24 hours so that any clorine in the water will evaporate.

5. Is the bird suffering from nutritional stress in that its food is not entirely suitable. An indication of this is the bird continually scattering its food as it tries to look for the items that it recognises as food.

6. Is the cage in an area which is too breezy or close to a window where it is subject to heat or cold.

You will see from the above that stress molt can be caused by one or more factors and you will need to consider your own situation and decide the most likely cause or causes and then eliminate it.

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