Part 3: Ringing your healthy birds. By Jim Hayward
If it is done in a discreet manner, cockatiels are usually very tolerant of nest inspection. Inspection must be carried out with the minimum of disturbance and preferably in the morning, so as to allow the pair sufficient time to settle back quickly onto their young or eggs. This might not be the case if the nest is looked into during late afternoon or early evening. Of course, it will be much wiser to wait until both parents are out of the box and in the flight.
The intruder may think a box of snakes has been opened up rather than a nest of birds, the hissing, puffing out of feathers and swaying to and fro is their defensive action designed to frighten off an enemy, and this threat display is taken up by parents and young alike.
Many breeders consider it best to contain their curiosity and leave nesting birds well alone, at least during the stages of incubation and the first few days of life of the hatchlings. Disadvantages of nest inspection include the possibility of chilled eggs, and causing desertion or crushing of eggs and young. Advantages include being able to check if eggs are fertile, to see that hatchlings are being fed and to remove any dead young which might cause infection to their siblings.