Fig 1.
a) Map of the roosting sites included in this study. The main roosts are represented with a circle. For these three roosts, social associations were recorded for the NBDA analysis. The secondary roosts are represented with a triangle. No social data was recorded at those sites, and the spread of the behaviour purely relied on individuals moving between the main and secondary roosts. The colours of each symbol represent the colour the two demonstrators were trained to use in each roost: red (Clifton Gardens—CG), blue (Balmoral Beach—BA, Manly—MA, and Botanic Gardens—BG), or white for the control group where no demonstrator was trained (Northbridge—NB). The black square represents an additional location where social data was collected (Spit Road, SP). The map was constructed in QGIS [51], using OpenStreetMap [52]. b) Male demonstrator of the CG roost during the preference test, shown in front of the experimental apparatus that dispensed blue and red coloured almonds. The dispensing side for each colour was alternated each day. c) Example of red and blue unshelled almonds. Almonds were safe for human consumption and were dyed using nontoxic food dye. Pictures by JP.
Fig 2.
Social networks of the study population.
(A) Network between neighbouring roosting communities, where edge labels represent the percentage of birds moving between sites. The network was constructed using GEPHI version 0.9.2 [53]. Orange circles represent the main roosts, grey circles the secondary roosts. (B) Social network recorded from the three neighbouring roost sites of BA (squares), CG (circles), and NB (triangles), including 322 individuals. Nodes represent individuals and the edges between nodes are scaled according to the proportion of all foraging observations where two individuals were observed foraging together during two 10 day social data collection periods. Node size indicates weighted degree, and nodes are coloured according to diet, i.e., red or blue if they ate the novel food (n = 197), and grey if they did not (n = 125). Node colour indicate individuals that displayed a preference for red (>50% solves on red) or blue (>50% solves on blue). The network was constructed in Gephi [53]. Edges below 0.10 are not shown for visual clarity. The data underlying this figure can be found in our data and code repository (https://doi.org/10.5281/zenodo.19052060).
Table 1.
Widely applicable information criteria (WAIC) estimates for all evaluated models with a 60 sec window of social information. is a model with a positive frequent dependent bias;
is a model of bias towards copying the behaviour of males;
is a model of bias towards copying the behaviour of adults;
is a model of bias towards copying individuals from the same roost;
is the model for individual learning.
Fig 3.
Posterior distributions of main learning parameters for each model.
Only the posteriors for individuals with known age and sex classes are displayed. Each column is a parameter. Each row is a model. Dotted lines show the prior used in each model. The data underlying this figure can be found in our data and code repository (https://doi.org/10.5281/zenodo.19052060).
Fig 4.
Individual-level acquisition curves comparing expressed choices against the frequency of behaviour produced in the previous 60 seconds, divided by age and sex class.
The dotted line shows the expectation under unbiased copying, and the shape of the curve is the estimated posterior mean of f from the frequency-dependent learning EWA model. Results suggest that juveniles disproportionately choose the food colour that the majority chose in the 60s previous, while adults are not influenced by the frequency of other’s choices. (a) Adults (>7 years), with females in orange, males in blue, and birds of unknown sex in green. (b) Juveniles (1–7 years), with colours as per (a). (c) Females, with adults in blue, juveniles in orange, and birds of unknown age in pink. (d) Males, with age coloured as per (c). The data underlying this figure can be found in our data and code repository (https://doi.org/10.5281/zenodo.19052060).
Fig 5.
Foraging on shelled almonds by cockatoos.
The pictures represent the remains of different opening techniques: two examples of “nibbling” starting (A) the hilum and (B) tip and an example of the (C) “splitting” technique. Pictures by JP.
Fig 6.
Behavioural sequences for successful almond openings across different roost sites (a: BA, b: BG, c: CG, d: MA, e: NB) and extraction techniques (f).
Opening stages are depicted from left to right: (i) whether individuals remove the outer layers of the shell (optional step, binary), (ii) at which location the shell is initially cracked (4 options: tip, hillum, middle, seam), and (iii) how the almond is subsequentially extracted (3 options: nibble, split, other). Males (M) are more likely than females (F) to show the ’splitting’ technique (p = 0.01) at stage 3 (panel f), and sites show significant differences in extractive sequences (p = 0.001). The data underlying this figure can be found in our data and code repository (https://doi.org/10.5281/zenodo.19052060).