The answer is that it is not a fixed problem.

It is borderline French Moult often associated with a long feathered bird(s) and the tail needs perfect nutrition to supply that to the growing feathers.

Anything short of that and the tail is the first item to be affected in an otherwise normal bird.

There is no proof at all that it can pass to other birds – so carry on and watch your nutritional input.

GSB

I have just started with budgerigars and got my stock from a champion.

On reading your website, I have now realised that I have got a lot of birds without tails!

I didn’t know that this was a problem.

Can you tell me if I should breed with them or not?

Will they have the same young?

David Taylor