Fig. 2

Plots comparing observed and expected values of partner presence at the nest before focal individual leaves the nest to forage using one pair as an example. Gaussian distribution of the expected values of the four different parameters (a female present when male leaves; b male present when female leaves; c a partner present when focal individual leaves; d at least one of the parents at the nest) of this pair as calculated with a randomisation process. Red dashed lines indicate observed values for that pair, which is in this case significantly higher than expected based on uncoordinated foraging trips