DOI: 10.5061/dryad.rbnzs7hb4
title: Cooperation-based concept formation in male bottlenose dolphins

description: In Shark Bay, Western Australia, male bottlenose dolphins form a complex
 nested alliance hierarchy. At the first level, pairs or trios of unrelated
 males cooperate to herd single females. Multiple first-order alliances
 cooperate in teams (second-order alliances) in the pursuit and defense of
 females, and multiple teams also work together (third-order alliances).
 Yet it remains unknown how dolphins classify these nested alliance
 relationships. We used 30 years of behavioural data combined with 40
 contemporary sound playback experiments to 14 allied males, recording
 responses with drone-mounted video and a hydrophone array. We show that
 males form a first-person social concept of cooperative team membership at
 the second-order alliance level, independently of first-order alliance
 history and current relationship strength across all three alliance
 levels. Such associative concepts develop through experience and likely
 played an important role in the cooperative behaviour of early humans.
 These results provide evidence that cooperation-based concepts are not
 unique to humans, occurring in other animal societies with extensive
 cooperation between non-kin.
description: The data were collected during August 2018 and 2019 in the
 eastern gulf of Shark Bay, Western Australia, where our research on
 Indo-Pacific bottlenose dolphins (<i>Tursiops aduncus</i>) has
 been carried out on a near-annual, seasonal basis (typically austral
 winter and spring) since 1982. We conducted playback experiments to male
 dolphins from three second-order alliances; the KS alliance (6 males), the
 PD alliance (5 males in 2018, 4 males in 2019) and the RR alliance (3
 males). We utilised a within-subject experimental design, where male
 dolphins were subject to signature whistle playbacks of males from their
 second-order alliance and males from their third-order alliance.
 We used a UAV (DJI Phantom 4 Pro+), with an integrated,
 gimbal-controlled camera (with a focal length of 8.8 mm and maximum
 resolution of 3,840 × 2,160 pixels and 23 frames/s), to obtain high
 quality visual records of how individual dolphins responded to the
 playback experiments. During each playback, the UAV was flown at altitudes
 (x̅: 34 m, range: 30-42 m, as determined by onboard sensors) to maximise
 our ability to detect behavioural changes but also maintain a relatively
 broad field of view. On playback of each stimulus, every effort was made
 to hold the UAV stationary above the animals in order to best assess
 behavioural responses. Using QuickTime
 player (v10.5), we scored the following variables from the videos of each
 playback experiment: (i) time to response (seconds) – time from the start
 of the first whistle stimulus to any visible response by the subject
 animal(s) to the playback; (ii) response duration (seconds) - time from
 the subject animal(s) first response to the playback until returning to
 pre-playback behaviour; (iii) approach distance (metres) – distance from
 first response until returning to pre-playback behaviour, estimated using
 adult dolphin body lengths (2 m) and corroborated with measurements and
 notes taken in real-time from the research vessel; (iv) delta orientation
 (degrees) - relative change in heading on response to playback, estimated
 in degrees; and (v) orient to source (yes/no) - a binary measure of
 whether the subject animal oriented directly toward the playback
 source. One observer (SJA)
 coded all 40 playback videos from the UAV footage, as well as the
 time-synchronised audio recordings from the hydrophones and voice notes
 (using Adobe Audition 13.0.3.60). A second observer (SLK), blind to
 playback treatments and the first observer’s scores, independently coded
 variables (i) through (iv) for all 40 playback videos: time to response;
 response duration; approach distance; and delta orientation. We then
 conducted an inter-observer reliability analysis using the intraclass
 correlation coefficient (ICC) for two-way models in the irr<i>
 </i>package in R 3.6.1 (R project for statistical computing; GNU
 project), and found strong agreement between observers (ICC = 0.976, P =
 &lt; 0.0001, CI = 0.967 - 0.983). Given this parity, we used the data
 scores by observer one in all further analyses and provide all playback
 videos here.
description: The videos are all
 approximately two minutes in length with 60 seconds pre-playback and 60
 second post-playback, with the playback occurring ~ 60 seconds into the
 video. The DJI Phantom 4 Pro+ stores videos in 4 GB chunks, if the
 two-minute playback period spanned two of these chunks then the playback
 will span two video files (totaling two minutes in duration). The playback
 number is visible in the file name, e.g., "PB1", and the
 corresponding data for that playback (focal ID, context, response
 measurements etc.) can be found in the Source Data file alongside the
 original article; King et al (2021) Cooperation-based concept formation in
 male bottlenose dolphins. Nature Communications. Please note, there is no video
 for PB17, this is also noted in the Source Data file mentioned above.
 Acoustic files are stored with the first author and can be made available
 upon request.