The efficiency of begging and pecking is plotted as a function of squab age.  Begging efficiency was computed by dividing the number of 10-s intervals in which the squab begged by the number of times they were fed by a parent during the first 60 min after light onset in the morning.  Pecking efficiency comes from an experiment in which squab were deprived of food overnight and then given a 20 minute test in which seed was spread across the floor of an aquarium.  Pecking efficiency is the total number of pecks divided by the total number of seeds eaten.