Two-action task, testing imitative social learning in kea (Nestor notabilis)

Abstract

Social learning is an adaptive way of dealing with the complexity of life as it reduces the risk of trial-and-error learning. Depending on the type of information acquired, and associations formed, several mechanisms within the larger taxonomy of social learning can be distinguished. Imitation is one such process within this larger taxonomy, it is considered cognitively demanding and is associated with high-fidelity response matching. The present study reproduced a 2002 study conducted by Heyes and Saggerson, which successfully illustrated motor imitation in budgerigars (Melopsittacus undulatus). In our study, eighteen kea (Nestor notabilis) that observed a trained demonstrator remove a stopper from a test box (1) took less time from hopping on the box to feeding (response duration) in session one and (2) were faster in making a vertical removal response on the stopper once they hopped on the box (removal latency) in session one than non-observing control group individuals. In contrast to the budgerigars (Heyes and Saggerson, Ani Behav. 64:851-859, 2002) the present study could not find evidence of motor imitation in kea. The results do illustrate, however, that there were strong social effects on exploration rates indicating motivational and attentional shifts. Furthermore, the results may suggest a propensity toward emulation in contrast to motor imitation or alternatively selectivity in the application of imitation.

Keywords: Emulation; Imitation; Kea; Nestor norabilis; Social learning; Two-action task.

Fig. 1

Kea test box specification, including feeding trays, and removable lid. Adjusted by a factor of 3.8 (incl. test box, feeding holes and stoppers) to the budgerigar test set-up to account for the larger size of kea

Fig. 2

Kea test cage set-up: A observation compartment view, B two tunnels up against mesh wire separation and C demonstration/test compartment view including test box with stoppers and removable visual barrier

Fig. 3

Test stoppers: on top and inside the test box; training stoppers with integrated discs from different angles (below and above)

Fig. 4

Log of the removal latency session 1 for control (green) and test (yellow) birds across trials in the first session. Boxplots show the median (solid line), 25th–75th percentile (box) and the largest and smallest value (whiskers). Dots reflects outliers. Note that the figures show the raw data and does not represent the fitted model with log (removal latency) as a response. Full-null model comparison: χ.² = 21.579, df = 3, P = 0.000079

Fig. 5

Logs of the approach pace, response duration and removal latency for females and males across all trials and sessions. Sex differences in A approach pace between females (F) and males (M), P = 0.0005; B in response duration between females (F) and males (M), P = 0.0119 and C removal latency between females (F) and males (M), P = 0.0079. Violin plots with boxplots showing the median (solid line), 25th–75th percentile (box) and the largest and smallest value (whiskers). Dots reflects outliers. Note that the figures show the raw data and not the corresponding models