Breeding and Reproduction of Pet Birds
All birds reproduce by laying eggs. Eggs are produced inside the female and then deposited in a nest. In captive female birds, egg laying, which is actually the equivalent of ovulation in mammals, can happen without fertilization or even the presence of a male. In some species, both female and male birds sit on the nest, while other species either leave this chore to the female only or leave it to nature to provide the warmth needed by the developing chick. In most species of pet birds, both parents are actively involved in incubation, feeding, and caring for the chicks.
Breeding birds and rearing chicks is best undertaken by an experienced bird owner. Most individual pet birds will not breed successfully in captivity. Requirements for breeding are complex and vary by species. Giving the full range of information is beyond the scope of this book.
If you are planning to breed your bird, you should have a thorough understanding of what is involved. By contacting and talking with an experienced breeder, you can learn about incubating, hatching, feeding, and judging whether or not your bird can or will take care of the chicks. Many inexperienced birds have trouble learning to care for their offspring, leaving the owner no choice but hand rearing the chicks. This can be quite challenging and time consuming, as the chicks must be fed on a regular schedule throughout the day. Hand raising also decreases a bird’s immune system strength, increases the chance of infection, and decreases necessary parental bonds. This can lead to behavioral problems later in life, similar to the relative attachment disorder seen in human babies deprived of physical contact.
Most male birds do not have a penis, which can be confusing for pet owners when trying to identify the sex of their birds. Identification of a male bird may be possible based on feather coloration or other physical features. However, most parrots are not sexually dimorphic—that is, males and females look the same. Sperm is produced in reproductive organs located well inside the body and then expelled into the female during copulation, in what is termed cloacal kissing.
In most female birds, only the left ovary is present. The ovary produces an unshelled egg which may then be fertilized by the deposited sperm. The newly fertilized egg then travels through the female, passing through several glands that add the egg white fluid (albumin) and deposit layers of shell material over the egg. The shelled egg is then expelled through the cloaca and deposited in the nest.
Female birds are receptive to male attention only at certain times of the year and under certain conditions (such as the presence of adequate nest boxes). Ask your veterinarian about breeding cycles for your species of bird. Also, female birds can be quite choosy about their mates; you may find that it will take several tries and exposure to different males, for your female to mate successfully. Factors such as age, environment, light cycle, presence of a suitable nest box, available food types, socialization, presence of other birds, and the presence or absence of potential predators (for example, dogs) will all influence whether birds will mate.
The time between mating to laying a fertilized egg and the length of egg incubation also varies between species. Your avian veterinarian can provide accurate estimates for your bird.
Successfully breeding and rearing birds is difficult and not something that most bird owners will do. This section is meant to provide general information, but not to provide a comprehensive guide to rearing young birds.
Chicks of most pet bird species are born blind and without feathers. Depending on the type of bird, the eyes open within 1 to 2 weeks. Feathering is complete in about 1 month for smaller birds but can take up to 5 months in larger birds, such as macaws.
Proper care during breeding, good sanitation and nutrition, nursery management, and egg incubation (if needed) can help reduce diseases in newborn chicks. Be sure to keep the cage in a warm spot away from any drafts. In general, chicks should not be disturbed but should be closely monitored to ensure that they are receiving proper care from the parents. If the newborns do not appear to be thriving, contact your avian veterinarian immediately for instructions on hand rearing.
As chicks get older, it is common for them to eat nonfood items that may be found in the cage. Loose bedding is a favorite for the curious chick. This habit may be related to normal curiosity, boredom, or a seemingly insatiable appetite. The result is that young birds often end up with foreign objects in the crop. A veterinarian may be able to manipulate the item back up the esophagus where it can be retrieved manually. In many cases, as with foreign objects such as jewelry screws, glass and other potentially abrasive items, surgery may be required.
Crop burns occur when birds eat food that is too hot. This is seen most commonly in baby birds being hand-fed. It usually occurs when the powdered formula is mixed with water that has been heated in a bowl in the microwave. Even when the temperature appears to be acceptable (103 to 105°F, 39.4 to 40.6°C), the formula will continue to warm as it absorbs heat from the bowl. The severity of the burn and the bird’s reaction vary greatly. Some birds become ill from the tissue damage and may die despite intensive care. Other birds have no signs and the burn is only detected when either food or a hole is noticed in the area of the crop.
If the burn is mild, swelling and redness will appear on the surface of the skin within several days. If the burn is severe, the chick may be very ill, refuse subsequent feedings, and need immediate veterinary care. The type of treatment depends on the degree of tissue damage. Mild burns may be treated with antibiotics and topical ointments, while severe burns may require life-saving supportive care, and later surgery to repair the damage.
This disease is caused by a high fat diet and may be seen in chicks (particularly cockatoo chicks) that are being hand reared. Often owners are unaware of the dangers of adding peanut butter, oil, or other high fat foods to the regular commercial formula, or they feed high-fat formulas (designed for macaws) to inappropriate species. Fat accumulates in the liver, interfering with normal liver function. Parrot chicks with fatty liver disease typically are heavy for their age and have severe trouble breathing.
Treatment includes removing sources of excess fat, reducing the amount of food provided in a single feeding, and adding digestive aids such as lactulose to the formula. Birds should be handled gently and as little as possible. If this disease is not detected early, and breathing difficulty has occurred, it is often necessary for the veterinarian to give oxygen, injectable fluids, antibiotics, and other supportive care to attempt to save the chick.
Young, recently purchased cockatiels may have low body weights for their age and a stunted appearance. These birds may have underlying congenital or developmental problems, including decreased liver function and decreased immune system competence. With supportive care, some of these birds will survive, but many will not. Birds that survive may have a fairly normal life or may require repeated veterinary care.
Another problem seen in young cockatiels is nicknamed the “one week post-purchase syndrome.” Cockatiels with this syndrome are often only partially weaned and are purchased soon after arriving at the pet store. In nature, they would be eating partially on their own but still receiving supplementation from their parents. When such a bird is sold as “weaned” to an uninformed owner, it generally takes about a week for the bird’s decreased food intake to create noticeable weakness. At this point, the infant bird is emaciated and dehydrated and may or may not respond to medical treatment.
Splay leg occurs when one or both legs are bent so that the chick is unable to stand properly. The cause of this abnormality is unknown. It can occur in most pet bird species but is most common in cockatiels. Parental “over-sitting,” nest box flooring that is too slick, birth defects, and nutritional deficiencies in the parents or young bird may all contribute. For young birds with splay leg, it may be helpful to keep each baby in a small container that does not allow the legs to slide out from under them sideways and to provide flooring that provides some traction. In cases where the legs are already splayed, a veterinarian can often correct the problem with splints, hobbles, or traction. The younger the bird is at the time of the attempted correction, the faster the recovery and the greater the success rate.
An underbite is a genetic abnormality in which the lower jaw outgrows the upper jaw. It commonly occurs in clutches (that is, several chicks from a single clutch of eggs). If the underbite is not too severe and is detected early, the jaw of the bird can be manually manipulated to avoid surgery. However, surgery can be successfully performed by veterinarians experienced in this technique and may be necessary in advanced cases.
Constricted toe syndrome is fairly common in infant birds, often affecting more than 1 toe. A band of fibrous tissue forms at the joint of the toe and interferes with normal blood circulation. This results in swelling, loss of blood supply, and finally death of the end of the toe. If circulation loss is severe and the tissue has died, amputation of the toe may be necessary. If this condition is recognized early, the fibrous band may be surgically removed to restore circulation. The cause of constricted toe syndrome is unknown.
Some birds are born with a condition called eyelid atresia, in which the eyelids are missing and the skin surrounding the eyes is fused together. The condition is most common in cockatiels and usually occurs in several members of the same clutch. If a sufficient opening for vision remains, the bird may lead a close to normal life. Attempts to slit the skin in this area and maintain the opening are rarely successful because the skin tend to seal together again as it heals.
“Lockjaw” is a bacterial infection of the sinuses and jaw joint of the chick. This syndrome can appear in clutches, most commonly in cockatiels. When the jaw joints are affected, the young bird may not be able to open its beak and may therefore starve to death, as it will be unable to eat.