Many pet owners will also add vitamins to the water, which will also have vitamin E as one of the ingredients. This vitamin in small amounts is an aid as an anti-oxidant nutrient. This vitamin is also used to increase productivity in animals and acts as a breeding stimulant. Other sources for vitamin E can be found in wheat breads, wheat germ cereals and some treat supplements. While a small amount of this vitamin is good, too much coming from different sources can be one of the reasons for your pet birds' behavior changes.
Lighting is another stimulant for egg laying in hens and aggressiveness in males.
As the days become shorter in the winter we all feel the need to add more light to our homes. For those of us who breed birds we purposely increase the light our birds are exposed to from 12 hours to 15 hours as we try to encourage our birds to cycle into breeding condition. Increasing the light your pet bird is exposed to will have the same result. Your hens will start laying infertile eggs and your males will become more aggressive. For those who have a hen as a pet, once she has began laying it is very important that you allow her to sit on the eggs as she lays them until she is no longer interested in them, this may take 2-3 weeks.