Chicks fully formed, but dead without pipping
Avian Incubation and Hatching
Eggs should be moved to the hatcher when the internal pip (or drawdown) occurs. Many aviculturists use their old incubators as hatchers, and many keep their hatcher in the nursery. Hatching actually begins three to four days prior to the expected hatch date. The hatcher should be set at 98.5 degrees F, or approximately one degree less than the incubator. The humidity should be high enough to prevent the hatching chick from sticking to the membranes and drying out. The wet bulb temperature, which measures humidity, should read 92-94 degrees F or higher. The hygrometer wick must be kept wet to give an accurate reading. As chicks hatch in the hatcher, the humidity will naturally rise.
Candling eggs is a very important skill. Eggs should be candled immediately after removal from the nest to check for fertility. The size of the air cell should be noted. Any shell abnormalities should be noted and corrected, if possible. Within 24-48 hours of pip, the egg will undergo drawdown, as the air cell changes shape. At this time, it is a good idea to candle the egg every 6-8 hours, and to place the egg in the hatcher, as turning is no longer required.
Damaged eggs can be easily repaired. If cracked eggs are not repaired, the egg will lose too much moisture during incubation, resulting in dead-in-shell (DIS) embryos, or the egg may become infected. Repaired eggs require special monitoring during hatch, as the repaired area may prevent the chick from hatching normally. Thin cracks can be repaired with water-soluble white glue. Several coats are usually required. Bite or toenail holes should be repaired. If the defect is too large to be corrected by glue alone, tissue paper may be used to cover the defect, using several coats. Repaired eggs should be hand-turned, and weighed frequently.
Recognizing DIS embryos by candling is an important skill. Early embryo death is easy to diagnose by the presence of a blood ring. Older embryos that die turn very dark as the blood supply recedes. Blood vessels indicate a viable embryo. If no active blood vessels are seen, or if patches of the shell are devoid of vessels, then that indicates DIS.