BREEDING         

Table of Contents:
           The Reproductive Cycle      Author: Pat Tucker (All Rights Reserved)
            Artificial Incubation          Author: Pat Tucker (All Rights Reserved)
            Veterinary Issues               Author: Pat Tucker  (All Rights Reserved)



                               THE REPRODUCTIVE CYCLE

Reproduction is ultimately linked to the survival of the species as a whole, but is not essential to the immediate existence of the birds partaking of the ritual. Consequently, birds will not breed unless all the appropriate elements are present to stimulate the onset of the reproductive cycle. To complicate matters further, breeding potential is buried deep within the hereditary makeup of each bird and what may stimulate one individual to reproduce may be very different from that which stimulates another.

Environmental and Psychological Stimuli: The onset of breeding behavior in birds is controlled solely by the production of hormones in the pituitary  gland and is a purely physical, rathr than conscious response. That is, birds do not decide to mate, instead their mating is the result of physiological responses.

The initial secretion of hormones (which is essentially the onset of the breeding cycle) can be enhanced by environmental and psychological stimuli such as:

                         1. Introduction of a nest box
                         2. Increased photo-light period
                         3. Increased availabilityof fresh food
                         4. Moisture simulated rainfall)
                         5. Temperature
                         6. Mate compatibility
                         7. Change in location

Pair Selection: Pair selection in our cockatiels should attempt to merge the physical and emotional traits of male and female with a goal of producing a percentage of offspring superior to the parents.  Birds displaying an inferior visual trait (e.g small head, short crest, etc.) or an emotional weakness (e.g. excessively timid or aggressive) should be paired with a partner who will offset that weakness.

Compatibility: Accurate determination of compatibility between a newly established pair will ultimately predict the level of breeding success. Mate acceptance can be identified during the first week with the observation of behavior changes such as establishing territory, courtship, pair bonding, and nest building. These activities are a direct result of the secretion of male and female sex hormones in the testes and ovaries and are sure signs of compatibility.

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Territory: Before coutship begins, most male cockatiels establish a territory. Although the territory required by a cockatiel is relatively small compared to other species, the ability to successfully defend the chosen space is paramount to breeding success. Since a great deal of energy can be expended establishing and defending territories in a colony breeding environment, housing pairs in individual fights or large breeding cages often enhances breeding results.

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Courtship: Courtship in cockatiels begins with the investigation of a nesting site. The male struts, sings, and taps his beak to attract the female to the nest, while often the female displays a coy demeanor. If courtship is successful, both male and female will start to redesign their nest and begin to form a pair bond.

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Pair Bonding: The intensity of a pair bond can reflect the degree of compatibility and, in the end, the level of reproductive success. A bonded pair shares activities such as eating, sleeping, nest building, and mutual preening. Cockatiels who display a strong pair bond will be more devoted to their partners, their nests, and ultimately, their offspring.

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Song and Vocalization: Male cockatiels utilize song to attract a mate, maintain a pair bond, establish territory, and stimulate breeding behavior. This activity is also stimulated by the production of sex hormones. Although other forms of vocalization are related primarily to survival, such as "sounding the alarm" when strangers enter the aviary or alerting a mate that a new supply of food has been offered, these calls are exaggerated during the reproductive cycle when defensive reactions are at their peak.

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Copulation: The urge to copulate intensifies as the testosterone level increases. In cockatiels, treading is from the side with the male mounting the female who has taken on the classic squatting position. During this process, the female emits a constant rhythmic sound while the male folds his tail underneath the female to make his connection. Copulation usually lasts for 2-3 minutes. Although it takes only one insemination to fertilize a clutch of eggs, the greater the number of matings the greater the chance that all the eggs will be fertilized. The sperm is deposted in the cloaca and travels up the oviduct to the ova. The highest percentage of fertile eggs occurs 2-3 days after insemination, with good fertility lasting up to 6-7 days. However, cocktiel hens have been known to lay fertile eggs as much as two weeks after the removal of a mate.

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Egg Laying: Once pair compatibility is established with the observation of hormone related activities such as courtship, pair bonding, nest building, and copulation, the arduous portion of the reproductive cycle, which includes egg laying, incubation, hatching and rearing of young is launched. During this critical time period the aviculturist who has learned the delicate 'art of intervention' has a distinct advantage. This art, which is fine tuned only with hands-on experience, can mean the difference between a cracked egg or a partial hatching, and a robust, healthy chick crying incessantly for its next meal. Learning the 'art of intervention' is truly knowing when interfrence will save a life or end one.

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Cockatiel hens lay a predetermined number of eggs which labels them as determinate layers'. This means that the clutch size, which typically ranges from 4-6 with an average of 5, is not influenced by the removal of eggs from the nest, unless they are removed as they are laid. In this case, the hen may be stimulated to lay more than one clutch sequentially. Laying is asynchronous in two day intervals, and most hens lay a consistent number of eggs per clutch or have a consistent laying pattern if the environmental conditions are stable (e.g., first clutch of 4 eggs and second clutch of 5), or some other consistent pattern depending upon the individual hen. This indicates that clutch size may be determined genetically, but it can be affected by age, food availability, nest size, and number of previous clutches. Although the hen has no conscious control over clutch size, she does have control over the actual laying of the egg, usually ensureing that the egg is deposited inside the nesting sute.

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Many cockatiel hens in 'laying mode' will display a labored posture which includes drooped wings, visible breathing, and occasionally a sleepy eyed appearance several hours before an egg is laid. This is not to be confused with egg binding which will include an enharged, hard abdomen, penguin-like posture and severe straining. Poor nutrition, lack of exercise, old age, over-breeding, internal tumors, or the production of an over sized egg can cause egg binding in cockatiel hens. Egg binding in a cockatiel hen should be treated as a medical emergency.

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Incubation: Once laid, the egg contains all the elements necessary for chick development except heat, humidity and oxygen. Heat is provided exclusively by the parent birds; humidity is partially provided by the environment and supplemented by bathing by the parent birds; and oxygen is absorbed solely from the environment through tiny pores in the egg shell. In cockatiels, both sexes participate in the incubation period lasting 18-21 days, which usually begins with the second or third egg. To assist in this process, the parent birds develop what is referred to as a 'brood patch' on their underside. This is essentially a thinning of the feathers and an increase in the blood vessels, which allows the brooding partent to detect even the slightest changes in the temprature of the egg. The ideal temperature is thought to be 98.5-99.5 degrees F., and the ideal humidity between 50% and 60%. However, the parents have a great deal of control over both factors if they fall below these recommended levels. Problems have been known to occur most often when the temperature and humidity levels rise above the normal range. Eggs must be turned an odd number of times each day and in a different direction each time. This procedure serves to warm the underside of the egg with each truning and distribute the temperature and food source for the check evenly through the egg while ensureing that the egg is positioned on a different side each night, the longest time lapse between egg turnings.

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There are several pitfalls to avoid during the incubation period, including constant nest inspections, candling, and egg cleaning. All too often, our natural curiosity or false sense of responsibility dictates our behavior during this 'waiting period' with disastrous results which can be manifested in cracked eggs, partially developed embryos, or nest abandonment. Too many intrusions into the nest can cause fear in the parents which increases the possibility of cracked eggs or spotty incubation and, the all too common practice of candling is an unnecessary risk. although it is true the veins can be seen in a fertile egg as early as five days, at nine to twelve days a fertile egg can easily be identified in the nest with the naked eye. The first egg laid should appear slightly darker and chalky against the lighter, translucent appearance of the more newly laid eggs. There are only three critical time periods during incubation in which inspection may be necessary.

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(1) The laying of the first egg so that a hatching date can be established for the nest

(2) Confirmation of fertility to determine if the pair will be allowed to incubate to full

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(3) Verification of the hatching process

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A further illustration of improper intervention by the aviculturist pertains to egg cleaning. Inadequate parenting skills may result in undesirable materials in the nest, such as fecal matter or food particles, which may adhere to the egg shells. If too many egg pores are clogged, enough life supporting oxygen could be resricted to cause the death of the embryo. However, despite popular belief to the contrary, egg cleaning frequently clogs additional shell pores which could worsen an already perilous situation. Here again, understnding the 'art of intervention' plays a significant role in the life or death outcome.

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The common stumbling blocks in the incubation process include: injury to eggs due to excessive nest interference, night fright, and inadequate brooding techniques due to inexperience, or poor synchronization between parents. The 'age factor' is significant during this state of the cockatiel breeding cycle. Statistics compiled at Feathering Crest Aviary over a 30 year period have indicated that hens younger than 24 months and cocks under 18 months undergo a learning period with their first clutches. Breeding results are better and bad habils are rarely formed when birds are allowed to mature to these ages before being set up for breeding.

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Hatching: Since cockatiels lay their eggs in two day intervals, hatching is asynchronous from the point of incubation. That is, if the parent birds begin to incubate with the laying of the second egg and five eggs are ultimately laid, the first two chicks may hatch within hours of each other, but the last three chicks will hatch at two day intervals. This mean that in a clutch of five eggs, there will be at least a six day age difference between the oldest and youngest chicks.

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The hatching process involves an intricate sequence of events which begins several days before the chick emrges from the egg shell. The chick develops hatching muscles at the base of the neck, an egg tooth at the tip of the upper mandible, and the air sac at the blunt end of the egg enlarges and draws down. Hatching begins when the chick penetrates the air sac and inhales air into the lungs.

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It is now that the real work begins for the unborn chick! There appears to be an internal pipping procedure which proceeds the external pipping of the egg shell. This occurs at least 24 hours before external pipping and it is probably during this time that the egg sac is drawn into the abdominal cavity. During this process, loud chirping sounds can be heard radiating from the egg shell and, in cockatiels, it is common to see internal pipping marks that leave protrusions without penetrating the egg shell.

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External pipping begins once the egg tooth is successful in penetrating the egg shell. During this state of the pipping process, the blood vessels in the inner membrane begin to drain and the chick continues pipping in a circular motion until the blunt end of the egg shell is severed. The chick kicks away the shell to finalize the hatching process.

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Hatching problems are often a result of improper incubation by the parents who may keep the temperature and humidity levels significantly higher or lower than the ideal ranges either due to inexperience or poor parenting skills. This may result in unretracted egg sacs, skeletal abnormalities, neurological problems, or adherence to the inside of the membrane. In cockatiels, it is most common to experience problems due to low humidity levels in the nest causing the shell membrane to dry out and the chick to adhere to it, usually at the wing or head. This may be complicated by the membrane drying sufficiently to adhere to both the chick and the egg shell and may cause poor calcium absorption to the chick. In these cases the chick begins pipping but is unable to rotate and sever the egg shell, and it may be necessary to assist in the hatching. If so, the egg shell should be gradually peeling away from the chick with a blunt instrument but, if bleeding is encourntered, it is an indication that the blood vessels in the inner membrane have not drained and hatching may be premature. In this case, moisten the chick with warm water using a cottom swab and replace the chick in the nest for a period of 30 minutes before continuing.

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ARTIFICIAL INCUBATION

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Choosing an Incubator:  There are two types of incubators available on the market today; forced air using a fan, and still air (or draft types using a natural convection. Although both may accomplish the task in the poultry industry, the forced air models are preferable for parrot eggs. Many models are available for $100-$500.

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Temperature: Embryonic development occurs between 97 degrees F and 102 degrees F but the higher the temperature, the faster the embryo develops and faster is not necessarily better. The optimum temperature is that which is identical to the natural incubation of the parent (approx. 98.5-99.5 degrees F), and there seems to be fewer problems with hatches when the incubation temperature is stabilized at 99.5 degrees F.

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Humidity: Eggs naturally lose weight during incubation due to fluid loss. The ambient humidity will dictate the amount of water that should be added to the bottom of the incubator to maintain the desired humidity level of 50-55%. A humidity measurer can be purchased and added to those incubators that are not equipped with one.

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Egg Turning: Eggs should be positioned on their side so that the small (or more pointed end of the egg is slightly lower than that of the larger (more rounded) end where the air sac is located. An egg that is placed on a flat surface will automatically assume this position. When automatic turning mechanisms are used, it is important to position the eggs according to these guidelines.

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Hand turning is preferable to automatic turning devices because it is a more natural turn. A gentle rotation of the egg from one side to the other, an odd number of times each day and in a different direction each time is strongly recommended. Hatchings have been successful with as few as 3 turns or as many as 21 turns each day. (Caution: Never turn an egg end-over-end as this may rupture the air sac.)

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Hatching: Approximately 12-24 hours before external pipping is expected or when signs of internal pipping are observed, turning should be ceased and the egg should be moved to a hatcher which is essentially an incubator designed for that purposed and set at a temperature of approximately 98.5 degrees F. Listening to the egg will help you determine when internal pipping has begun as a tapping sound is emitted from the egg. When internal pipping has ended and external pipping is ready to begin, the chick will emit a rhythmic peep. Additional humidity is often required during this time, and adding a bowl of water to the hatcher will usually accomplish this goal. Hatching is most often uneventful.

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Hatching Assistance: Determining the point of intervention is a difficult process. If 24 hours have past following the onset of internal pipping and external pipping has not begun, careful egg monitoring is warranted. Listen to the egg for vocalization. If chick vocalization is present, this means the chick has pipped through the internal membrane into the air cell and is breathing air. The entire process may take as long as 48 hours from internal pipping until hatching. Most hatchings that are assisted by the aviculturist are done as a safeguard to prevent the possible occurrence of a full-term dead-in-shell chick and not because it is absolutely essential. If proper procedures are followed, there is little risk to the chick.

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Unless chick vocalization resembles a distress signal, hatching asistance should be postponed until external pipping has begun. Chip away the egg shell at the pip site, moisten the internal membrane to reveal any undrained blood vessels. If no blood vessels are present or the few that remain appear brown rather than red in color, hatching assistance may continue. Gently break through the membrane with a blunt instrument (i.e., toothpick). In bleeding occurs, apply pressure to the bleeding site until the bleeding stops and return the egg to the incubator for a period of 30 minutes. Once the blood vessels are completely drained, gently peel the shell away from the top half of the chick and remove the white canopy membrane. As the chick wriggles out of the shell, observe the naval area to determine if the egg sac has been retracted. If an unretracted egg sac is present, leave the chick in the bottom half of the shell and replace it in the incubator until it is completely absorbed or becomes a hard pea-like protrusion. At this time, the chick can be removed from the remaining egg shell.

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Feeding from the egg: Newly hatched chicks experience a natural waiting period between hatching and feeding whereby the absorbed egg sac continues to fulfill its nutrition needs. During this time-period, there is a lack of feeding response from the chick and oftentimes (especially if there has been a hatching assistance), the chick remains positioned on its side in the hatcher, appearing lethargic. Within an 8-hour period, the chick's physical position changes from the lethargic position to an upright position and active begging is observed. This posture is usually accompanied by a feeding response which indicates the need for external nourishment. Chicks should be fed at 1-2 hour intervals for the first 4 days from 6am to 11pm, with an additional 3am feeding (optional) using a diluted formula. During days 4-9, feedings can be stretched to 3 hours, the formula thickened slightly, and the 3am feeding eliminated. After 9 days, 4 feedings a day with regular strength formula will suffice.