DOI: 10.5061/dryad.4f4qrfjgm
title: Wild kangaroos become more social when caring for young and may maintain long-term affiliations with popular individuals

description: Kangaroos are an iconic group of Australian fauna. Despite considerable
 research on kangaroo behaviour, key gaps remain in our understanding of
 their social organization in the wild. In particular, it remains largely
 unknown whether kangaroos form long-term social bonds and what factors
 might prompt individuals to associate or dissociate from one another. Over
 6 years, we monitored the social affiliations of individually identified
 eastern grey kangaroos, Macropus giganteus, in a large wild population. We
 investigated the short-term and long-term relationships of kangaroos and
 the extent those relationships varied with age, sex and reproductive
 state. We found evidence that long-term relationships among eastern grey
 kangaroos are possible, especially between adult females. Those
 individuals that were more sociable within years were also more likely to
 establish affiliations across years. Contrary to previous studies, we
 observed females actively associating with other mothers in the years in
 which they had young. These data suggest that the fission-fusion dynamics
 of eastern grey kangaroo social behaviour allow females to modulate their
 social position with conspecifics according to their current reproductive
 state. We highlight the adaptive implications of the formation of
 long-term bonds and the changes in social behaviour observed in females.
description: The study was based on identifying individual eastern grey
 kangaroos from high-resolution digital photographs. These were taken
 during a systematic annual survey of a wild population on private property
 near the locality of Wollar in the New South Wales Central Tablelands.
 This population ranged in size from 34 to 71 individuals. The photographic
 survey was conducted annually over six years (2015–2020) by the second
 author and at approximately the same time each year (see below for the
 exception). The survey was done in the Austral spring, except for 2016
 when it took place in winter. Photos were taken using a 200mm lens on a
 Canon EOS 7D digital SLR from portable hides placed at least 12 hours
 prior to the first day of observation. The survey was conducted over two
 to three hours at dawn and again at dusk for three to four consecutive
 days. This population of eastern grey kangaroos was
 particularly suited for this study because individuals rested during the
 day within a eucalypt woodland surrounding an open grassy valley. At dusk,
 kangaroos progressively moved out into the grassland of the valley from
 the woodland to graze and ultimately dispersed out into the surrounding
 areas around the valley after dark. At dawn, kangaroos would return to the
 valley to graze until mid-morning and then return to shelter in the
 eucalypt woodland. This meant hides could be strategically placed around
 the valley in order to survey virtually all individuals residing in the
 valley. Hides would be entered at least an hour before dawn and prior to
 kangaroos returning to the valley, and again at mid-afternoon before
 kangaroos had left diurnal rest spots inside the eucalypt
 woodland. Multiple photos of individuals and their
 associates were taken to ensure kangaroos could be adequately identified
 in most instances. Each annual survey typically resulted in a photo
 library of 500 to 700 images and was considered to be an exhaustive survey
 of all individuals residing in the valley. In general, a photographic
 survey is an optimal choice for kangaroos because of its minimal
 invasiveness (e.g., Austin and Ramp, 2019). Similar survey designs have
 also been used to take representative ‘snapshots’ of population dynamics
 in eastern grey kangaroos (Toni et al., 2021) and other animals (Piefke et
 al., 2021).
description: Data files can be accessed through Microsoft Excel.
description: # Wild kangaroos become more social when caring for young and may maintain
 long-term affiliations with popular individuals MS Authors: Campbell, Nora
 E; Ord, Terry J ## FILE NAME AND CONTENT Campbell\_Ord\_data.xlsx All data
 used in analyis of kangaroo social networks. ## FILE STRUCTURE AND UNITS
 OF MEASUREMENT The file is a xlsx file that can be opened using any text,
 spreadsheet or statistical program. ## xlsx file column headings
 Descriptions for the headings in the .xlsx file are given below. ### Roo *
 The individual kangaroo, given by a number, predated by the sex/age it was
 last seen as. E.g. Roo f4 is kangaroo 004, who was last seen in 2020,
 identified as a female. ### sex * The sex/age of the focal kangaroo in a
 given year. Females with and without young are categorised seperately. ###
 Date * The date that the photograph used to identify the kangaroo was
 taken. ### Time * The time that the photograph used to identify the
 kangaroo was taken. ### AM/PM * The time of day the data was collected. AM
 data was collected shortly after sunrise until mid-morning. PM data was
 collected from mid-afternoon to sunset. ### All other individuals within 3
 m * All other kangaroos seen within an estimated 3 meters of the focal
 kangaroo. ### Males * The number of males in the photograph with the focal
 kangaroo. ### Females without Young * The number of females with no young
 in the photograph with the focal kangaroo. ### Females with Young * The
 number of mother kangaroos in the photograph with the focal kangaroo. ###
 Fully emerged juveniles * The number of juveniles belonging to the focal
 kangaroo (only valid if the focal kangaroo was a female with young), that
 are fully emerged from the pouch. ### Other juveniles * The number of
 juveniles not belonging to the focal kangaroo seen in the photograph with
 the focal kangaroo. ### Unknown * The number of kangaroos in the
 photograph with the focal kangaroo whose sex cannot be determined. ###
 Observed ID'd Associates * Individual kangaroos (represented by a
 number) that are seen in the photograph with the focal kangaroo. ## DATA
 COLLECTOR * Photographs used in the study were taken by Terry J. Ord.
 Kangaroos were identified from these photographs by Nora E. Campbell.