The effects of female group-changing behavior on female-female aggression, female rank, and female hierarchy stability

It is unclear how habitat features alter animal response to social instability. Only by uncovering such interactions can we fully understand the evolutionary drivers and fitness consequences of sociality. We capitalize on a management-induced manipulation of social stability in an island population of free-ranging feral horses (Equus caballus), living across three distinct habitat types. We tested whether female group-changing behaviour (a reliable measure of social instability) affected 1) female-female aggression, 2) rank within female dominance hierarchies, 3) stability of female hierarchies (in the groups they joined and/or left), and 4) how habitat characteristics shaped these responses. Female group-changing behaviour positively predicted aggression from other females, but only when habitat features such as visibility and freshwater distribution were considered. We found no strong association among female group changing behaviour and the aggression initiated, female rank, or the s..., Behavioural and demographic sampling
Comparable to previous studies, data were collected across 7.5 weeks in 2021 (June – July) and 8 weeks in 2023 (June – August), totaling 697.15 hours of behavioural observation (379.9 hours, 2021; 317.25 hours, 2023), averaging 4.72 ± 0.61 hours per mare (range = 0.5-14.25 hours). We recorded all instances of female-female aggression including displacements, bites, kicks, and pushes [25]. Each female’s aggression rate was calculated as the total number of aggressive interactions (either initiated or received) / the total number of hours she was observed. Only reproductive mares (aged 4 years and older) for which we collected at least three hours of data were included in our analyses (n = 51). When possible, animals were observed during both years of the study; two main factors precluded this for some animals: 1) field logistics (finding and then observing animals on foot) required that only mares that could be located on a consistent basis were obser..., , # The effects of female group-changing behavior on female-femaleaggression, female rank, and female hierarchy stability

[https://doi.org/10.5061/dryad.vhhmgqp3z](https://doi.org/10.5061/dryad.vhhmgqp3z)

## Description of the data and file structure

### Files and variables

#### File: CHANGES\_AND\_ELO\_BIO\_LET\_20241025.R

**Description:** R code for analysis regarding the effects of female group-changing behavior on female dominance hierarchy stability

#### File: CHANGES\_WITH\_RANK\_AND\_AGG\_BIO\_LET\_20241115.R

**Description:** R code for analysis regarding the effects of female group-changing behavior on female-female aggression and female rank

#### File: agg\_and\_rank\_data\_BIOL\_LETT\_20241025.csv

**Description:** Data for analyzing the effects of female group-changing behavior on female-female aggression and female rank

##### Variables

* year:
* horse:
* mareage:
* region:
* no_trts:
* no_changes:
* total_agg_given:
* total_agg_rcd:
* ch_per_hour:
* agg_given_per_hr...