Everybody has opinions of why some have heavy loses and difficulty in birds finishing a race series. Most fanciers say it is the difficulty of the race conditions (weather), others say the young age of the birds, others the frequency of the races and some the quality of the birds. Everyone is entitled to his opinion, but my opinion and reasons are completely different.
I believe the major reason for the heavy looses is one of the following or a combination of several of reasons below:
Birds are not fed properly.
Birds are over trained.
Birds are not medicated properly.
Birds are not educated.
Birds are overcrowded in flying loft.