The length of a female adelie penguin foraging trip after being prevented from going to sea

One potential proximate cause of the timing of the nest relief cycle of adelie penguins was investigated by testing the hypothesis that the females count the days that they are gone from the nest so they can return to relieve the fasting male before he abandons the nest. Females were prevented from going to sea, after they finished laying their eggs and had left their nest, for 4 days (the average delay caused by laying a third egg in the first experiment) and the duration of the foraging trip was determined.