A wide and varied range of factors can lead to low egg output, poor hatch rate or infertile eggs. Today I’d like to present a general framework for looking at the problem. I’ll address individual topics in detail in future articles…please also see the other articles on this blog, noted below, for further information.
It is important to be well-versed in the natural history of the species that you keep. Knowing when your birds breed in the wild will give you an indication of what might stimulate them in captivity. Having a compatible pair is often not enough to insure success – the hen may lay, but fertility can be affected if natural breeding stimuli are missing. If you are experiencing difficulties, go beyond avicultural articles in your reading and look how the bird lives in nature…most of what we know about breeding animals of all types originated in this manner.
An increase in temperature, day length or humidity/rainfall may be required. In many cases, light timers, humidifiers and portable room heaters can be used to create the appropriate conditions.
The appearance of a nest box or suitable nest site can be a powerful breeding stimulus, especially when combined with other environmental changes as mentioned above.
Weather and seasonal changes often bring with them novel food items, or an increase in the availability of certain foods. The provision of live insects is a time-honored zoo and avicultural technique for certain species. Budding trees, sprouting grasses or the ripening of specific fruits may also be important in stimulating reproduction…again, it is important to study your bird’s natural history.
Same-sex pairs form among captive birds of many species. For those which are not sexually dimorphic, courtship behavior may not be a reliable indication of a successfully mated pair. Sexing via feather analysis or laparoscopy may be necessary.
Paired birds that live together but fail to mate are sometimes stimulated by a period of separation.
Imprinted, hand-raised and fostered birds sometimes fail to form pair bonds and mate successfully.
Review your bird’s diet carefully, as vitamin and mineral deficiencies are often behind infertility. Obesity is a cause for concern as well.
Inbreeding can reduce fertility. Inbreeding depression is especially common among rare birds which originated from a small pool of founding stock. You may also run into this problem with common species if you consistently purchase your birds from the same source. Check that your supplier deals with various breeders, to assure that the birds in your collection are more likely to be unrelated.
If all else seems in order, you may wish to have your birds evaluated by a veterinarian, to rule any of the more commonly encountered avian reproductive disorders.
Further information on this topic may be found in the following articles: