Plastic eggs are a very useful tool when breeding is in full swing and can be used in a number of ways. Plastic eggs can be used to delay the fertilization process, retain heat allowing the hen to leave the nestbox longer to feed or mate, prevent chicks once hatched being squashed or used to replace the hen’s eggs when the eggs are to be transferred to a foster pair.
Let me explain that after mating has taken place and the hen has laid the egg the hen and sometimes the cock need to use the body heat to start the embryo developing. Heat is required to start the process and depending on how tight the hen sits the egg, you can normally see a red vein after four days which will continue to form the chick (checking for a fertility by using a torch light is called candling).
You can remove the egg and store in a safe place replacing the egg with a plastic egg substitute, you may wish to remove the second and third egg also replacing with plastic eggs. After the fourth egg is laid remove two of the plastic eggs and put the hens eggs back in the nestbox. Budgerigar normally lays a egg every other day and the difference in size between the first hatched and fourth can be considerable by removing three eggs until the fourth egg is laid we can now have all four eggs hatching on the same day.
Choosing to not use plastic eggs and that is your choice for me l prefer to use plastic eggs in some circumstances l will remove the eggs as described above but it is not the norm.