The timing of nest relief is crucial to the nesting success of adelie penguins. Experiments were conducted to test whether the physiological conditions of the female will determine how long she stays at sea to feed. Stressed females should stay at sea longer and the male mate would have to shorten their foraging trip to match the date of hatching accurately. At least one adult penguin was banded ... from each pair that had eggs collected (for another study on energetic value of eggs). Removal of one egg caused most females to lay a third egg. The duration of the first, second and third foraging trip (FFT, SFT, TFT), the time from the beginning of the FFT until the end of the TFT, the time for each egg to hatch, the time from the laying of the final egg until the first egg hatched (apparent hatched time) and the guard stage (first hatch until the first day both parents absent) were measured and compared with control nests. Eggs in the nest may also give a clue to the adults, especially in the few days before hatching. Newly hatched chicks starve within a few days if a well fed adult is not there to feed them. Adults may therefore be able to regulate the length of the TFT to suit the amount of time remaining before the eggs hatch. Clutches of early and late eggs were cross fostered and the above parameters measured and compared with control nests.