DOI: 10.5061/dryad.cnp5hqcfz
title: Dispersed female networks: female gorillas’ inter-group relationships influence dispersal decisions

description: Dispersal is a fundamental aspect of many animal societies, impacting gene
 flow, knowledge transmission, culture, and individual fitness. However,
 little is known about the information individuals use when dispersing.
 Mountain gorillas exhibit a flexible dispersal pattern with 50% of both
 sexes dispersing from their natal groups, and females often dispersing
 multiple times. Using two decades of data, including 152 dispersals from
 56 females, we examined how familiarity with individuals in other groups
 influenced dispersal. We found that females avoided groups containing
 males from their natal group, but preferred groups containing females they
 had previously resided with. This suggests that females prioritise the
 maintenance of female relationships in their dispersal decisions, whilst
 reducing inbreeding risks. Joining a new group can be costly, and these
 pre-existing relationships may therefore reduce these dispersal costs.
 These findings highlight the capacity for wider-scale societies to both
 shape and be shaped by dispersal decisions, with long-term inter-group
 relationships representing potential sources of information and support in
 the dispersal process. This not only contributes to a better understanding
 of population dynamics in this endangered ape, but also of the foundation
 of our own flexible society, characterised by individuals moving between
 social groups throughout their lifetimes.
description: # Data for: Dispersed female networks: female gorillas’ inter-group
 relationships influence dispersal decisions ## Description of the data and
 file structure #### **Final_model_1_anonymized.xlsx** *Description*: Each
 event number represents a unique dispersal event. There are multiple rows
 per event, with date, ID, age, and the previous group of the female
 remaining consistent within each event. The column 'group'
 represents all the study groups, except the one in which the female
 resided, as potential dispersal options. The data was used for Model1a and
 Model1b. The column 'Selected' can be either 1 or 0, depending
 on whether the female chose to join the group (1) or not (0). For each
 event, there is exactly one row where 'Selected' is 1, and all
 the other groups for that event are assigned 0. For each group, additional
 information is provided: *Variables* nb_member: The group size,
 representing the number of individuals in the group older than 6 years.
 nb_silverbacks: The number of males older than 12 years. nb_adult_females:
 The number of females older than 8 years. annual_overlap: A measure of the
 overlap between the home ranges of the female's previous group and
 the potential dispersal group, ranging from 0 to values greater than 1.
 distance: The spatial distance between the female's previous group
 and the potential dispersal group (km). visual_interaction: The number of
 visual interactions with the group in the 365 days preceding dispersal.
 auditory_interaction: The number of acoustic interactions with the group
 in the 365 days preceding dispersal. natal_males: The number of natal
 males in the group. natal_females: The number of natal females in the
 group. non_natal_males: The number of males from a non-natal group.
 non_natal_females: The number of females from a non-natal group. parallel:
 Whether the event took place in parallel with other individuals;
 1=parallel, 0=non-parallel. parallel_buddies: The number of individuals
 with whom the female dispersed. #### **Final_model_2_anonymized.xlsx**
 *Description*: Each row represents an inter-unit encounter. For each
 encounter, the female's ID, age, and current group are provided,
 along with the group's start and end dates for her residency. All
 inter-unit encounters occurring within this period, as well as their
 respective dates, are listed. The dispersal column indicates whether the
 female dispersed during the encounter (0=no, 1=yes). As in Model 1, for
 each group, additional information is provided. This dataset is used in
 Model 2 as well as in Duration of co-residency and Time since last
 co-residency. *Variables* current_group_nb_member: The group size,
 representing the number of individuals in the female's group older
 than 6 years. interaction_nb_members: The group size, representing the
 number of individuals in the encountered unit older than 6 years.
 diff_groupsize: interaction_nb_members-current_group_nb_member.
 current_group_sb: The number of males older than 12 years in the female
 group. nb_silverbacks: The number of males older than 12 years in the
 encountered unit. diff_sb: nb_silverbacks-current_group_sb
 current_group_nb_of_receptive_females: the number of receptive females in
 the female's current group. This is calculated as the number of adult
 females with no dependent offspring and not giving birth within 2 months
 of the encounter (latest stage of pregnancy).
 interaction_nb_of_receptive_females: the number of receptive females in
 the encountered unit. This is calculated as the number of adult females
 with no dependent offspring and not giving birth within 2 months of the
 encounter (latest stage of pregnancy).
 diff_receptive_females: interaction_nb_of_receptive_females
 - current_group_nb_of_receptive_females visual_interaction: The number of
 visual interactions with the group in the 365 days preceding the
 encounter. auditory_interaction: The number of acoustic interactions with
 the group in the 365 days preceding the encounter. natal_males: The number
 of natal males in the group. natal_females: The number of natal females in
 the group. non_natal_males: The number of males from a non-natal group.
 non_natal_females: The number of females from a non-natal group.
 group_category: Group versus solitary males (1 versus 0) been_in_group:
 Whether the female has ever resided in the encountered group (yes=1, no=0)
 *The other columns indicate the number of individuals by the duration of
 co-residency and the time since last co-residency with the focal female.*
 natal_male_0_2y: The number of natal males the female last resided with
 between 0 to 2 years. natal_male_2_25y: The number of natal males the
 female last resided with between 2 to 5 years. natal_male_5_10y: The
 number of natal males the female last resided with between 5 to 10 years.
 natal_male_10y_more: The number of natal males the female last resided
 with more than 10 years ago. natal_male_duration_0_2y: The number of natal
 males the female resided with during 0 to 2 years.
 natal_male_duration_2_5y: The number of natal males the female resided
 with during 2 to 5 years. natal_male_duration_5_10y: The number of natal
 males the female resided with during 5 to 10 years.
 natal_male_duration_10y_more: The number of natal males the female resided
 with for more than 10 years. natal_female_0_2y: The number of natal
 females the female last resided with between 0 to 2 years.
 natal_female_2_25y: The number of natal females the female last resided
 with between 2 to 5 years. natal_female_5_10y: The number of natal females
 the female last resided with between 5 to 10 years. natal_female_10y_more:
 The number of natal females the female last resided with more than 10
 years ago. natal_female_duration_0_2y: The number of natal females the
 female resided with during 0 to 2 years. natal_female_duration_2_5y: The
 number of natal females the female resided with during 2 to 5 years.
 natal_female_duration_5_10y: The number of natal females the female
 resided with during 5 to 10 years. natal_female_duration_10y_more: The
 number of natal females the female resided with for more than 10 years.
 non_natal_female_0_2y: The number of natal females the female last resided
 with between 0 to 2 years. non_natal_female_2_25y: The number of natal
 females the female last resided with between 2 to 5 years.
 non_natal_female_5_10y: The number of natal females the female last
 resided with between 5 to 10 years. non_natal_female_10y_more: The number
 of natal females the female last resided with more than 10 years ago.
 non_natal_female_duration_0_2y: The number of natal females the female
 resided with during 0 to 2 years. non_natal_female_duration_2_5y: The
 number of natal females the female resided with during 2 to 5 years.
 non_natal_female_duration_5_10y: The number of natal females the female
 resided with during 5 to 10 years. non_natal_female_duration_10y_more: The
 number of natal females the female resided with for more than 10 years.
 **Note on missing data:** In *Final_model_1_anonymized.xlsx*, a few cells
 in the distance and annual overlap columns contain 'n/a' values.
 These indicate cases where there were insufficient data to calculate these
 metrics reliably. * **Distance**: This value could not be estimated when
 fewer than three GPS points were available within the 7 days prior to the
 female’s departure. * **Annual overlap**: Annual home range overlap was
 not calculated for groups with fewer than 50 GPS points over the year. In
 such cases, the corresponding cells were marked as 'n/a'.