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. In not getting maternal antibodies, baby birds that are hand raised may have a decreased immune system response, an increased chance for developing infections, and a weaker bond with parents. These factors may contribute to the development of behavioral problems later in life.
Males
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–-and the only way to tell the sexes apart is through DNA testing of blood or feathers. 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.
Females
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 passes out of the uterus into the cloaca—a common chamber into which the reproductive, gastrointestinal, and urinary tracts empty. Then the egg passes from the cloaca through the vent opening to outside the bird.
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.
Care of Newborns and Young Birds
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.
Swallowing Foreign Objects
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
The crop is a pouch-like dilation of the esophagus located in the bird’s neck into which food passes from the mouth before it moves through the lower esophagus to the stomach. Crop burns typically occur when hand-fed birds are fed food that is too hot. 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.
Fatty Liver Disease
Fatty liver disease is typically caused by owners’ or breeders’ hand-feeding a high-fat diet to try to get chicks to gain weight quickly. It has been documented more commonly in cockatoos. Often, owners are unaware of the dangers of adding peanut butter, oil, or other high-fat foods to commercial hand-feeding formulas, or they feed high-fat formulas (designed for macaws that require higher fat in their diet) 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 may have severe trouble breathing due to the presence of large amounts of fat internally.
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.
Birth Defects and Developmental Problems
Young, recently purchased hand-fed birds may have low body weights and may look stunted. These birds may have underlying congenital or developmental problems, including decreased liver and immune system function. Even with supportive care, not all of these birds will survive, and those that do may develop repeated illnesses that require veterinary attention.
Problems also occur in birds that are weaned off hand feeding formula too early or are sold before they are completely weaned. They may appear fine initially, but because they do not yet know how to properly themselves, they gradually become weak and lose weight during the first week or two after they are sold. These birds become emaciated and dehydrated and need immediate veterinary care to survive.
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 young birds, especially Eclectus parrots and macaws, and it often affects more than one 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 suspected to be too low humidity in the nest box or brooder as chicks grow and develop.
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. If lockjaw is suspected, a bird should be taken to a veterinarian right away to receive antibiotic treatment and supplemental feeding.
