Breeding Too Early

• Allowing birds to breed too early in the spring will often result in infertility. Since the canary breeding cycle is dependent on the number of daylight hours, breeding birds before Valentine's Day often results in infertile eggs. Make sure that the canaries receive 13 hours of light to prepare them for breeding. Covering the cage from dusk to dawn helps, but make all changes in light amounts gradually.
  
  

Condition

• Birds that are too fat or too thin, may not be able to produce fertile eggs. If they are too fat, they may not be able to get into breeding position. If they are too thin, they may lack the proper nutrients to produce fertile eggs. Adding extra protein and vitamin enriched seed to their diet may be necessary.
  
  

Perches

• Make sure all perches are securely fastened to the cage. If the perch is unstable, successful fertilization may not be possible.
  
  

Loud Noises

• Since canaries are known to have very poor night vision, loud noises and bright lights like those from thunderstorms can scare them into leaving their nests and eggs. Often they are unable to find their way back before daylight, allowing the eggs to cool off. This can sometimes result in the death of the embryos.
  
  

Handling

• Check eggs for embryos two or three days after the hen begins to sit on them. To do this, carefully remove them from the nest and hold them up to a light. Clean hands are absolutely necessary for doing this as any substances on your hands can pass through the shell and kill the developing bird.