Q: We have been successfully breeding several different types of conures, including suns, for more than five years. Last year, we purchased a proven pair of sun conures from a close friend. The pair has laid four clutches of eggs since we’ve had them, but every egg has been infertile. We know that they were a good pair because we used to buy their babies. Their diet and caging are the same as where they came from. What could be the problem?

A: Virtually all infertility is caused by problems in one of four areas: nutritional, physical, social or environmental. If all the criteria in each of these four areas are met satisfactorily, then success is assured. Every pair of birds is unique to some extent. How far you can stray from the absolute ideal situation and still have successful production varies with each individual pair. Just because a large number of pairs finds a particular situation acceptable does not mean that every newly acquired pair will also react the same.

The details you have provided narrow the field of possible answers to your pair’s problem. The first possibility is that the male is marginally ill. Marginal illness in either the male or the female can be responsible for infertility. Since the female has laid four clutches of eggs in succession, she is probably well. I would have the male examined by an avian veterinarian to eliminate illness as the cause of the problem. All that is usually necessary to find out if you are on the right track is a simple white blood cell count. If his count is normal or only slightly elevated, then the problem lies elsewhere.

In the vast majority of cases like this, the problem is that the male is either angry or intimidated, and his preoccupation with these feelings keeps his mind off procreation. In short, he hates where he is. This situation is created either by a flight cage that has its highest perching point too close to the ground, or by what the male can see from inside his flight. Many indoor aviculturists stack their cages. A pair that is used to being up high in the top flight will often stop producing if moved to a lower level. If this is not the problem, then perhaps it is something he can see. He may hate his neighbors. He may be intimidated because they are bigger than he. He may resent the fact that their cage, or for that matter their highest vertical perch, is higher than his. These types of problems can be avoided by arranging your aviaries and placing your perches so that no one is higher than anyone else. Also, try to keep birds of the same size together. If you were a sun conure, you might feel intimidated if you were next to an aggressive male mitred conure. If these situations cannot be rectified, then you may want to consider installing blinds between the cages. Another very common problem that creates this situation is a cage with a group of immature or unattached birds within view of your breeding pairs. A cage full of last year’s babies or your extra males or females can only be a negative influence. This is not to say that a large percentage of pairs will tolerate this situation. If there is a problem, however, all possibilities must be considered.