Sheet 1: 2022
Head turn data was only collected in 2022; thus only n=93.
Used for analysis of differences between FC, PC1 and PC2, and for differences in head turn frequency by age.

Condition = Condition type (PC1, primed condition 1; PC2, primed condition 2; FC, free condition)
	PC1 and PC2 were summed due to insignificant differences between them -> PC.

Average_Head_turns_per_minute = average number of head turns counted per minute the individual was in camera view

For Approaches and Pecks:
No = no peck/approach occurred
Yes = approach/peck occurred irrespective of colour-match
Cor = peck at/approach towards the crisp bag that colour-matched the hand-held one
NCor = peck at/approach towards the crisp bag that did not colour-match the hand-held one
Both = both colour-matched and non-colour-matched approach/peck occurred

Approach_YN and Peck_YN are occurrences of approaches and pecks irrespective of whether they occurred towards the biased side.



Sheet 2: 2021 and 2022 summed
Combined peck and approach data from 2021 and 2022; thus n=183.
Used for analysis of approach and peck occurrence, age differences in approaches and pecks, as well as investigation of whether gull choices matched the hand-held item.

Held_Item and Pecked_Item are the colours of the crisp bags (blue and green) held by the experimenter and chosen by the gull, respectively.
This was used to test whether Held_Item influenced Pecked_Item.


Sheet 3: Directness
Scores of directness (1=least, 5=most direct) given by an independent observer.