Recently, a friend of mine has issue with one of his breeding female white-rumped shama: egg binding. According to my friend, he saw the female stands/lay on the floor of the aviary in the morning, fluffy feather, and seems to have hard time breathing. Normal bird should perch on the tree branch, alert and active. As seen before in previous year, he immediately caught the bird and bring her inside the house in bamboo cage and use incandescent light to keep her warm. He then gave her few drops of liquid calcium. Few hours later, she is able to lay the egg, and seems to recover the ordeal.
In two years of bird keeping, I hear few stories of egg binding in pet birds, especially around breeding season start. Lucky for me, I haven't have this issue in all of my birds (knock on wood ;) ). Female bird when in breeding season need great amount of calcium (usually stored in the bone) to be able to form eggshell properly. Once the reserved calcium is depleted, some calcium from her own bone will be use. And when there is not enough calcium to form eggshell, the egg inside her body will has soft shell and it can cause the female bird great difficulty to lay.
Lacking of calcium in daily diet is the main cause for egg binding in pet birds, especially insectivore bird like white-rumped shama. According to bird keepers in Asia, supplement normal daily insect diet with small vertebrate animals such as small lizards, froglet, small fish, or feeding small shrimps with shell once in a while can be enough to reduce this egg binding issue. In country like where I live, small lizards and froglet are almost impossible to find, and small fish (even feeder fish) is somewhat expensive, supplement daily diet with either liquid or powder calcium is almost the only choice to prevent this issue.
For those who keeps pet birds indoor, even with plenty calcium supplement, the female bird might still get egg binding. The cause is not due to lack of calcium, but lack of Vitamin D3. Vitamin D3 is the only vitamin D form that the bird can use, found only in animal products such as eggs, milk, insects, and liver or synthesize by the bird when bird is exposed to sunlight. The short wavelength ultraviolet light in the sunlight aids in the formation of vitamin D3 on the skin. The exposed skin of the legs, feet, around the eyes, and in other areas on some birds, exude an oily compound called technically 7-dehydrocholesterol. When the ultraviolet rays strike this substance, they produce a chemical change that transforms it into cholecalciferol, or vitamin D3. The vitamin is then resorbed into the skin over a period of time to supply the birds' vitamin D requirement. These ultraviolet rays cannot penetrate window glass, though they will go through quartz glass and most clear plastics. Vitamin D3 is crucial for the absorption of calcium into the body. Without vitamin D3, whatever amount of calcium the bird eat, it will come out the bird body with all the undigested wastes.
Other causes include obesity, lack of exercise, oversized or mal-formed eggs, excessive egg laying, oviduct infection or damage, heredity and senility are all causes of egg binding.
Sign of egg binding: according to Linda Pesek (DVM) in her article "Egg binding in breeding and pet birds" here are some of the clinical signs: "A hen may appear depressed, have an abnormally wide stance, and make repeated straining motions. Some birds may be puffed yet perching, while others may be found on the bottom of the cage. Some birds may even be found dead on the floor of the cage or aviary without any previous warning. Droppings may be larger than normal or no droppings may be passed and the vent may be dilated and swollen."
Treatment: As in case of my friend, keep the bird warm (85-95F) and give couple drops of liquid calcium will do the trick, but it's all depend on when you discover the bird has issue with egg binding, and other factors such as how poor condition of the bird is. Again, here is what Linda Pesek wrote: "Egg binding should be considered an emergency. Medical treatment is initiated to stabilize the bird. The bird may be given fluids intravenously or subcutaneously as well as antibiotics, steroids and calcium. It is placed in an incubator at 85-95 degrees F with moistened air. If the egg is not passed within a few hours, additional calcium as well as certain drugs to stimulate contraction and expulsion of the egg may be administered. Sometimes it is necessary to sedate the bird with isoflurane and manually pass the egg. If this is not possible due to the large size of the egg, ovocentesis or aspiration of the egg's contents, followed by collapse of the egg and removal of the shell may be necessary." Ovocentesis or aspiration of the egg's contents can be done by using syringe with sharp needle to puncture the eggshell and remove the contents inside. Once the egg collapse, the shell can be remove using small forceps. I would imagine this process is very tricky to do and risk of infection is very high. Sterile all equipments use, antibiotic might need to give to the bird after the procedure, and proceed with great care.
Long term prevention: Review the daily diet and make change if necessary. Adding calcium supplemental 3-4 times weekly during breeding season and 1-2 times weekly when outside breeding season can help. Provide the bird with natural sunlight few hours daily or use artificial light bulb that specifically made to help bird/reptile produce vitamin D3 regularly to ensure bird can have enough vitamin D3. Give plenty of room for the bird to exercise. Observe the bird carefully during breeding season to caught the sign of egg binding early.