Great tits choose between food and proximity to a mate

Summary These experiments test for time of day differences in the attentiveness of territorial, paired, male and female great tits (Parus major) to their mates, by requiring them to choose between feeding and being in sight of their partner. There was a strong time of day effect favouring proximity to a mate early in the day for both males and females. A difference in male and female behaviour that would have suggested that this was male mate guarding was not found. Three independent measures show that this temporal effect is not owing to foraging being more important in the afternoon. There was a significant within-pair correlation in the strength of this proximity effect, which was strongest early in the day. Possible functional explanations are discussed. When females moved out of sight of males, male vocal behaviour increased and this increase was much greater when females moved out of sight earlier in the day than later on. These effects were not observed among females. This result is consistent with the hypothesis that male mate guarding is most important early in the day.