By Penny Corbett
Why can't my baby birds get out of the shell in time? They get a sack on their abdominal area and end up dying.
It is difficult to provide an answer that may directly help your situation without knowing the species of bird you are writing about. It is possible that the species you are trying to successfully breed may require special incubation conditions. In order to provide you with information that will assist you in producing viable chicks, I will cover the basics.
There should be no doubt that your parent birds are a male and female that know how to mate, where to lay the eggs and how to incubate. Diet, location, security and other factors have been covered in recent past columns. Please refer to these columns if you have any doubts regarding such factors. As long as these needs are met, and there are no genetic or disease factors, the next issue to consider is at what point the eggs are being manually opened.
Incubation periods differ among the species commonly bred, and this period may vary by a couple of days. Not all hens start incubating with the first egg. Some wait until the second egg or so is laid before they start incubating the clutch. This is simply a personal preference of the hen. If you have more than one pair of the same species, you may find that some begin incubation when the first egg is laid and some wait until the second or third egg. Incubation periods are not necessarily written in stone. You should keep and maintain records on each pair that include the mutation (when applicable), number of eggs laid per clutch, number of fertile eggs per clutch, number of chicks hatched and hatch dates, number of chicks weaned and band numbers of those chicks. The data you collect will give you a profile on each pair that will be fairly consistent. Use it to determine the good parents from the marginal or poor parents. The data will also help you know when to expect chicks to hatch and about how many.
The Hatching Process
From your description, the eggs are being opened at least a couple of days too early. When chicks are normally ready to hatch, they have absorbed the yolk sack. There is a process to hatching that takes time and is usually followed during a normal hatch. As hatching time approaches, the chick's head lies under the right wing and the tip of the beak is toward the air cell (located in the large end of the egg). When the air cell enlarges and drops (referred to as drawdown), the chick begins to move its head into the air space made by the drawdown. Some chicks begin to vocalize at this point, but they are not yet ready to hatch. If you candle the egg (care needs to be taken not to drop or crush the egg. If you are not comfortable with candling eggs, do not do it), you will be able to see the chick's head in the air space. The next step is the internal pip when the chick breaks through the inter-membrane to the air cell. This is about the time the yolk sac starts to retract. The chick then makes its first external pip through the shell and begins to breath the room air and vocalization can be heard. The chick continues to rotate in the shell and cut its way out of the shell. In time, the chick pushes off the top of the shell and completes the hatching process. The process from internal pip to complete hatch can take from several hours to a few days, depending on the species.
Eggs can develop a bit differently, and chick position within the egg can vary a little and still hatch successfully. Premature intervention in this process normally causes the death of the chick. The chick does not necessarily start the hatching process and continue until it has hatched. Again, depending on the species, they will have periods of rest. Hatching is time-consuming, hard work. The bird breeder should not get anxious if a chick is not proceeding as quickly as he or she thinks it should.
There are other factors involved in and during the hatch that have not been covered here. This column only explains the time and partial process involved.
Knowing When — And When Not — To Help
When hatching assistance becomes routine, it is time to examine all of the factors involved and correct the problem. The eggs you describe were not at the stage of development for an embryo ready to hatch. They are being opened too early, which is resulting in their death. This is an error in judgement made by many novice bird breeders who believe they are rescuing a trapped chick. Assisting in the hatching of a chick should only be done when it is absolutely necessary. Even then, it should only be done with expert guidance or by someone with the experience to do it successfully.
Columnist Penny J. Corbett has been breeding birds for more than 25 years. She has experience showing and judging many species, including color-bred and type canaries, finches, and softbills. She currently breeds mainly hookbills.