Relative diets preference
We recorded the number of birds feeding on a given food tray at every 60 seconds interval across the four aviaries within an hour with a telescope stationed 25 m from the aviaries. We carried out observations in the morning (1000 – 1100 hrs. GMT) and evening (1600 - 1700 hrs. GMT) of three selected days per week. We recorded the identity and sex of foraging individuals throughout the experiment. Also, we weighed (±0.1 g) the amount of food left on each food tray (defined as giving up density, hereafter GUD) three hours after food was provided using a digital weighing scale. We measured GUD at 0900, 1200, and 1500, 1800 hours for food provided at 0600, 0900, 1200, and 1500 respectively.