Why do cockatiels and some of the other smaller species of pet birds produce eggs when there is no male present?
Over the last few years, female cockatiels and other small pet bird species have accidentally been selectively bred for their ability to lay eggs without a mate present. We need to look back a few generations to find the source of the problem. Veterinarians, breeders and hobbyists have, in error, advised owners that a mate should be provided for these egg-laying pets. This is, in fact, the last thing that you want to do. Laying too many eggs can be a health hazard for a hen. Breeding her will increase the number of birds with this problem in the future.
The poultry industry has used this selective breeding technique in a positive way to significantly increase egg production in chickens. The original chicken was a small bird that laid an average of seven eggs each year. Today, with selective breeding and proper nutrition, the average chicken produces 252 eggs per year.
The hen that lays the most eggs and the most clutches of eggs in her life, produces the most babies. Super-producing hens are showing up at an increasing rate and developing into a major health problem for small companion birds. Professional and hobby breeders alike, utilize these abnormal hens to produce as many babies as possible for the pet trade.
Some of the female babies produced by these prolific hens will also have the ability to produce many eggs. If these females end up in a breeding situation, they will also produce a lot of babies and end up passing this trait on to more female babies. Over the last 20 years, some of these very prolific hens have caused these super-ovulating genes to be fixed into a significant percentage of the cockatiel and other small bird populations.
This situation is not limited to small birds. Because of the older age at which many of the larger parrots start to produce, they have not had as many generations of production. Smaller birds can begin reproducing at one year old while many of the larger parrots take five to ten years. This problem has developed in about 15 generations for the smaller birds. In about another 25 years, it will likely be as common in the larger parrots.
Problems that can arise A few of the birds that develop this problem will not suffer any undesirable effects. Unfortunately, this is not the situation for most of these birds. Many undesirable problems and situations can develop when a bird becomes a chronic egg layer. These problems include but are not limited to:
- Aggression - the pet may become territorial and aggressively defend her territory.
- Egg binding - the bird's system may not be able to provide the significant amount of resources necessary to produce so may eggs. Insufficient calcium reserves result in the oviduct not being able to provide the calcium lubricant for the egg to pass. The egg can become stuck and the bird will die without veterinary intervention.
- Lack of pet appeal - because the birds is always sitting on eggs, she may not be an interactive companion.
- Lack of exercise - a broody bird wants only to sit on eggs. This lack of exercise is OK for a normal period of incubation, but a chronic egg layer can experience several inactive months each year.
- Calcium depletion and many resulting health problems - Egg production requires significant amounts of calcium, protein and fat. Inactivity, loss of appetite, and a significant loss of calcium can result in too many short and long-term health problems to list here.
What starts the egg laying process? All birds have the same list of environmental requirements for beginning the egg laying process. They include, among other things, a mate, a nest, plenty of food and the right amount of daylight. In a wild situation, these requirements are similar in all birds of the same species. The natural selection process (survival of the fittest) keeps the breeding requirements similar in all individuals.
In captivity, most babies are kept alive regardless of their ability to survive in the wild. Some of these captive birds have slightly unusual requirements from the signals they would go by in the wild. If, for instance, a wild bird had the genes that allowed her to begin laying eggs before the days were long enough, the babies would die because it would be too cold or there would not be enough food. In captivity, these same birds would do just fine.
Over several generations, captive birds that have the least rigid breeding requirements produce the most babies. Eventually, a species develops such a wide range of acceptable breeding requirements, that they will lay eggs anytime, even without a male.
Solution:Do not breed your pet if she lays eggs without a male present - you will be part of the problem for future generations. Careful attention will help to eliminate the problem or at least limit it to one clutch of eggs per year.
Even though some hens are very adaptable when it comes to breeding environment requirements, we can usually stop the process by changing the environment. When changing the environment does not work, there are additional medical interventions that can be utilized. Below are listed several factors to consider. Once the egg-laying behavior is recognized, you may be able to tell she is getting ready to lay about a month in advance. Awareness of the time of the year when the behavior starts will help in avoidance the next year if there is a yearly cycle to your pet's behavior.
Avoid sexual stimulation by owner. During breeding season, a male will be more attentive to the hen. He will spend more time defending and preening her.
Petting and touching by the owner can be sexually stimulating, especially when touching the cheeks, lower back or abdomen. Once she starts to respond to this physical stimulation, you may notice her lifting her tail in preparation for the male to mount her. When she displays this behavior, put her back in her cage for a few minutes until the behavior changes. Continued stimulation could turn this behavior into a habitual behavior. When this happens, the owner can end up being the stimulus that keeps starting the cycle.
By the time you notice this behavior, it may be too late. Once the ovulation cycle has started, you will not likely stop it. Careful observation of subtle body changes leading up to this behavior will help you with early warning signals the next time.
Do not unknowingly provide a nest site. I often suggest that pet bird owners supply small boxes for birds to play in and tear up. Normally, this is great entertainment and will not cause a bird to start ovulating. Sometimes owners go a step further and provide a real nest box for their pet to play in. This is never a good idea even with a normal hen.
In abnormal circumstances, small boxes (potential nest sites) may be a significant contributing factor initiating egg laying. Once you become aware of your pets abnormal tendencies to lay without a mate, you will want to be careful to avoid providing this stimulus in the future.
Do not pull the eggs. Most birds are 'determinate layers'. They lay a set number of eggs for each clutch. This number will vary slightly, about five to eight for cockatiels, but will stop when she gets to her limit. When you pull the eggs, an abnormal hen may keep laying. Since the hen is not getting the correct tactile feedback to her abdomen from touching eggs, she may keep laying until her system is totally drained of calcium and other nutrients. If the eggs are removed within the hormonal period that allows for producing a second clutch she will produce even more eggs. This situation can escalate into a chronic egg laying problem.
Supply a nest to hold the eggs. Though you never want to provide a nest before a bird starts laying, once egg laying begins, you will want to supply something to hold the eggs. A dish with a small amount of wood shavings or tissue paper in the bottom will work. Place any eggs she has already laid in the dish and she will likely begin to set on them and lay the rest of the clutch.
Do not make her too comfortable. Nest sites usually have a lot of requirements for a normal bird. We do not want to provide a nice nest box that meets all of the criteria of a great home and encourages her to continue laying.
Some abnormal hens will have a tendency to lay many eggs, but lack the desire to brood (incubate) the eggs. This is a double problem because the hen may not be able to stop producing eggs until she becomes sick, or worse. In this case, it may become necessary to provide an appropriate nest site so all of the nest site cues are present to try to turn on her brooding desires.
Provide lots of high quality food. One normal clutch of eggs under normal circumstances will not harm a bird. Laying too many eggs in a row or too many clutches each year, can completely deplete all of the birds nutrient reserves. During normal or abnormal egg laying periods, it is advised to provide high quality food sources. If your bird is on a seed diet, this will be very difficult. Birds on pelleted diets will easily switch to a breeding pellet that will supply all of the necessary nutrients.
Change environment. Many different possible breeding stimulus make it difficult to determine just which ones are turning on the switches for ovulation in your pet's brain. One of the easiest ways to change many of these stimuli at the same time is to move the cage to a different location, and preferably, a different room. Each location will have among other stimuli, a different amount and intensity of daylight, slightly different temperature, and a different amount of activity and privacy.
Induce molt. Molting hens will rarely produce eggs. Molting in a breeding bird normally occurs after the eggs are laid and the babies are weaned. Inducing a molt about a week after a hen lays the last egg of a clutch will hormonally interrupt the next ovulation cycle and stop the process for the season.
Both chemical and environmental methods are available to induce a molt. A veterinarian can introduce drugs that will cause a bird to start molting. A less invasive method involves making a few changes to the environment.
Two significant changes occur at about the time a bird would be weaning its young. The parents are losing a little weight because they have been spending so much time feeding and caring for their babies, and at the same time, the days are getting shorter.
The poultry industry recognized this long ago. Chickens that have produced eggs for about eight months begin to produce irregularly and become unprofitable. If the farmer wants to restart the ovulation process, he must first stop it altogether. This is accomplished by shortening the day length to eight hours and removing 10% of the feed and water for three or four weeks. The bird's brain thinks it is fall, stops production and begins molting.
Chemical birth control. Birth control pills for birds will likely become available for parrots in the near future. Currently, there are drugs available that any avian veterinarian can administer. Unfortunately, we do not have enough experience in this area and still find inconsistent results in different individuals. Dr. Branson Ritchie, at the University of Georgia, has been working on this solution for several years.
Hysterectomy. Removal of the uterus and the oviduct will stop egg production.
Hysterectomy involves a significant degree of risk for several reasons. This procedure is difficult and invasive and most veterinarians do not have much experience with this procedure. In addition, the risk of death under anesthesia on a debilitated bird is very high.
Additionally, the bird may continue to exhibit all of the other breeding behaviors associated with egg laying. Only the most serious cases should consider this procedure.
Future possibilities. There has been some research done on surgically sterilizing baby parrots. This process is similar to the methods used with dogs and cats. However, even on young birds with undeveloped gonads, it is still a difficult and dangerous process.
Chemical sterilization of young parrots may be available at some time in the future. This process has not yet been developed for birds, but should work the same as in mammals.
Conclusion: When this problem presents itself, it is important to allow it to run its course. Pay attention to as many of the environmental factors and your birds behavior as you can. Good observation is the best way to manage the problem in the future.