Sterility in Amazons

© Howard Voren. Click here to use this content.

Q: We have a female yellow-naped Amazon who laid infertile eggs for three years in a row. We had the male rechecked by our vet, and he said that the bird was fine. The vet agreed with what everyone had been telling us. They all say that if the female is laying, she’s all right, and that the problem is with the male. We sold the male to someone who wanted him for a pet, and we used the money to buy a replacement male. He checked out okay with the vet, and our hen accepted him. We have seen the birds copulate, and it appears that they engage themselves in the proper fashion. Unfortunately, she has laid two more clutches of infertile eggs.
Are we just very unlucky, or is there a problem with finding fertile male yellow napes? All of these birds have been imports. Do the drugs that they receive during quarantine make the males sterile?

A: “If a female lays infertile eggs, the male is at fault.” This is one of the many false “facts” that are all too common in aviculture today. This one is especially interesting. It is assumed almost universally as fact. The interesting thing is that, to the best of my knowledge, it has never appeared in print. This one seems to have dropped down from the sky! Nobody even knows who they originally heard it from. They just know that everyone knows it’s true! I have yet to see any scientific basis for this assumption. In fact, with yellow napes specifically, I have proven to myself that it is more often the fault of the hen. Fifteen years of breeding yellow napes has given me quite a few opportunities to switch around birds.

I have re-paired females that lay infertile eggs with males that have proven themselves fertile. At the same time, I have re-paired these supposedly sterile males with the producing females with which the other males have proven themselves. More often than not, the females that were fertile with the proven males were also fertile with the males that were assumed to be sterile. Also, the females that were previously infertile continued to be infertile even though they were with highly experienced proven males.

As far as your question concerning the fertility of birds that have been through quarantine, don’t worry. This misconception dates back to the old days when we were still trying to blame our avicultural failures on everything other than our own incompetence. The fact is that the USDA would not allow the use of such drugs in their quarantine program, if in fact they do exist. I was, at one time, approached by someone who wished to investigate the possibilities of distributing sterile Quaker parakeets. The sale of Quakers is banned in several states because they are worried that escapees could start feral populations and compete with native wildlife. This person believed that the rules could be changed if only sterile birds were sold. Investigation as to how to accomplish this revealed that short of individual surgery, there is no simple way to sterilize a bird.