# Natal dispersal patterns in a social wild mammal: what does family tell us?

Marlène Gamelon, Jean-Pierre Coudrin, Gilles Capron, Alise Gilot, Éric Baubet, Jessica Cachelou, Jean-michel Gaillard

► To cite this version:

Marlène Gamelon, Jean-Pierre Coudrin, Gilles Capron, Alise Gilot, Éric Baubet, et al.. Natal dispersal patterns in a social wild mammal: what does family tell us?. Ecology, 2025, 106 (9), pp.e70190. 10.1002/ecy.70190. hal-05247389

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1 Journal: Ecology

2 Manuscript type: Report

3

4 Natal dispersal patterns in a social wild mammal: what does family tell us?

5

6 Marlène Gamelon¹, Jean-Pierre Coudrin², Gilles Capron³, Alise Gilot¹, Éric Baubet⁴, Jessica

7 Cachelou¹, Jean-Michel Gaillard¹

8

9 ¹Laboratoire de Biométrie et Biologie Evolutive UMR 5558, CNRS, Université Claude

10 Bernard Lyon 1, Villeurbanne, France.

11 ²Société de Chasse Militaire de Fontevraud 49 et 86, 49590 Fontevraud-l'Abbaye, France.

12 ³Office Français de la Biodiversité, Direction Régionale NA, Service Connaissance, Faubourg

13 de la Cueille Mirebalaise, 86000 Poitiers, France.

14 ⁴Office Français de la Biodiversité, DRAS-Service conservation et gestion des espèces à

15 enjeux, Montfort, 01330 Birieux, France.

16

17 Correspondance: marlene.gamelon@univ-lyon1.fr

18

19 **Open research statement:** Data are published in Zenodo

20 https://doi.org/10.5281/zenodo.15960315.

21 **Keywords:** distance, kin, propensity, repeatability, sex-specific dispersal, *Sus scrofa*, wild

22 boar
23 **Abstract**

24 Natal dispersal is a key process in ecology and evolution. Similarities of dispersal patterns
25 between relatives can lead to small-scale kin structure within populations with consequences
26 on population dynamics and genetics. Most studies have focused on birds, lizards, and small
27 mammals. How family effects may shape sex-specific natal dispersal patterns in a large-sized
28 social mammal remains unexplored. We fill this gap thanks to a 30 year-long monitoring of a
29 wild boar population. This polytocous, polygynous, and size dimorphic species displays a
30 matrilineal social organization. From the monitoring of individuals from early life to
31 adulthood, we characterized natal dispersal patterns by investigating the propensity to
32 disperse and the dispersal distance. As expected for a species subjected to strong sexual
33 selection, offspring males dispersed more often and farther than females. Looking specifically
34 at similarities of dispersal patterns among relatives within a group, we found that offspring
35 females from the same family displayed more similar dispersal propensity and distance than
36 females from different groups, highlighting family effects. However, this dispersal pattern did
37 not hold for males. Family effects can thus shape natal dispersal patterns in a sex-specific way
38 in social mammals, and are key to understand individual variation in dispersal patterns.
39 **Introduction**

40 Natal dispersal corresponds to the movement between the natal area or social group and the
41 area or social group where first breeding takes place, and is a key process in ecology and
42 evolution (Clobert et al. 2001). Dispersal has strong influences on both individual fates,
43 population structure and performance (Clobert et al. 2001). Dispersing from its natal area
44 could have clear fitness benefits, such as leaving a poor area, avoiding competition with kin,
45 or avoiding inbreeding. But natal dispersal has also some fitness costs, involving e.g. a risk of
46 death during the transient stage, a risk of being harassed by conspecifics when settling a new
47 range, or a risk of performing sub-optimally in an unfamiliar environment (Jungwirth et al.
48 2023). Benefits and costs of natal dispersal strongly vary both spatially and temporally, so
49 that the payoff of dispersing is context-dependent. The questions “*should I stay or should I
50 go?*” and “*if I go, how far should it be?*” are thus of prime relevance for any non-sessile
51 organism, and the decisions taken depend on both the set of individual attributes and the
52 environmental context.

53 Natal dispersal is a complex process shaped by individual phenotypic attributes (e.g. sex,
54 body size, condition), pre-natal maternal effects (e.g. maternal condition), post-natal maternal
55 effects (e.g. location at birth, early-life home range) (Massot and Clobert 2000, Pasinelli and
56 Walters 2002) and by population density during early life (Matthysen 2005, Gaillard et al.
57 2008). Moreover, early-life environmental conditions experienced by offspring may shape
58 their dispersal patterns. Thus, a natal habitat preference induction (NHPI) can favor the
59 dispersal of individuals towards habitats resembling their natal habitat (Davis and Stamps
60 2004). Among those factors, the similarities of natal dispersal among relatives play a crucial
61 role because they lead to small-scale kin structure within populations (Matthysen 2005) with
62 consequences on population dynamics and genetics. Although several case studies have
63 looked for similarities of dispersal between relatives in vertebrates (see Massot and Clobert
2000 for a review), most have focused on birds, lizards, and small mammals. For instance, among the 22 case studies listed in Massot and Clobert (2000)'s Table 1, none has been performed on a large mammal, likely because dispersal propensity and distance are difficult to study in the wild for large species.

Empirical evidence of family effects on natal dispersal is limited and the strength of similarities of dispersal patterns among offspring from the same “family” can vary according to the sex of the individuals. For instance, no correlation was found between dispersal distances of siblings and no sex effect occurred on dispersal distance in the California spotted owl (*Strix occidentalis*), but no owls settled at isolated or unoccupied sites (Lahaye et al. 2001). On the other hand, mixed-sex sibling pairs remained close right after fledging more often than similar-sex pairs in the borrowing owl (*Athene cunicularia*) (Catlin and Rosenberg 2014). Recent studies in birds have provided further evidence that offspring sex may shape the level of similarity in dispersal patterns among kin. In the Florida scrub-jay (*Aphelocoma coerulescens*), social dynamics had sex-specific effects on dispersal patterns (Suh et al. 2020), with e.g. the presence of a stepfather inducing earlier dispersal for males, or high-ranking and singleton females dispersing shorter distance.

Natal dispersal patterns can greatly vary across social mammal species (see Clutton-Brock and Lukas 2012 for a review on social dispersal in mammals). Some species are philopatric, with individuals of one sex (often females in mammals, Pusey 1987) remaining in their natal group throughout their life, whereas individuals from the other sex disperse (in e.g. social rodents, primates, or bats). Alternatively, individuals can disperse from their natal group to breed (in e.g. carnivores, equids, or monkeys). Between the two extreme cases, philopatric and disperser individuals of a given sex coexist. In social species displaying natal dispersal, a key question is whether dispersal among kin is independent or not, and when not, how kinship influences sex-specific natal dispersal patterns. To the best of our knowledge, these questions
89 have remained unexplored to date despite the rich literature existing on the dispersal process.

90 We aim here to fill this knowledge gap by assessing the extent to which family effects may
91 shape natal dispersal patterns in a social mammal in the wild, and whether this influence
92 differs between sexes.

93 To do so, we took advantage of a 30 year-long monitoring of a free-ranging wild boar (Sus
94 scrofa) population. This is a polytocous species, with females able to produce large litters (up
95 to 14 piglets) (Gamelon et al. 2013). The social system is described as a matrilineal social
96 organization (Dardaillon 1988), with adult females generally grouped with their young. After
97 weaning, females remain with their mothers, generating mother-daughter associations that last
98 over time (Kaminski et al. 2005, Focardi et al. 2015), while males leave the social groups at
99 about one year of age (Truvé and Lemel 2003). Thanks to the individual monitoring of several
100 hundreds of individuals of both sexes from early life to adult stages, we identified dispersal
101 patterns by measuring two key metrics, namely the propensity to disperse and the dispersal
102 distance. We tested whether offspring sex may shape the level of similarity in dispersal
103 patterns among kin. More specifically, we tested three predictions. (P1) Sex-biased dispersal
104 is widespread across animal species (e.g. see Trochet et al. 2016 for a review on 257
105 vertebrates and arthropods species) and several hypotheses have been proposed to account for
106 that. Under the “local mate competition hypothesis” (Dobson 1982), the sex suffering the
107 most from intrasexual competition should disperse more. We thus predicted that (P1)
108 offspring males should disperse more often and farther than offspring females because this
109 species is highly sexually dimorphic in size (Veylit et al. 2021) and polygynous (Poteaux et
110 al. 2009). (P2) The NHPI hypothesis (Davis and Stamps 2004) posits that individuals tend to
111 disperse towards habitats resembling their natal habitat. While exploring habitat
112 characteristics of natal and breeding habitats is beyond the scope of the present paper, we can
113 derive from that hypothesis that offspring males exhibiting long dispersal distances should be
in social groups with offspring females displaying long dispersal distances, so the median dispersal distance displayed by offspring males and offspring females from the same social group should be positively associated. (P3) Offspring sex may shape the level of similarity in dispersal patterns among kin (e.g. Catlin and Rosenberg 2014). Given the matrilineal social organization, we predicted that (P3a) offspring females born in the same social group should display more similar dispersal propensity and distance than offspring females from different social groups, after having disentangled the social (family) effects from the spatial (location) effects; (P3b) within a social group, offspring males should not display more similar dispersal patterns than offspring males from other groups, because males are theoretically more prone to live solitary when adult than females living in social (family) groups.

## 124 Materials and methods

### 125 (a) Study site and data collection

The study site is located in western France in the 3,250 ha open military camp of Fontevraud-l'Abbaye (47°10'N; 0°02'E). Hereafter, the definition of “year” is based on hunting seasons, thus starting in October 1st and ending in September 30th the next civil year. From 1992 to 2023, between June and August, a mark-recapture-recovery program allowed us to capture wild boars with traps at 26 different locations within the military camp (Appendix S1, Figure S1A). At each capture, individuals were ear-marked with unique ID, and the date at capture, the exact location of the trap, the sex, and body mass (in kg) were recorded before releasing them. Later, individuals can be killed by hunting within or outside the military camp during the hunting season, from September to February (Appendix S1, Figure S1B, C) or died from car collision. Drive hunting consists in pushing out animals with dogs to posted hunters who then shoot wild boar without any possibility to identify their sex or age. The ID of marked individuals, the date and the exact location of the death were recorded. In total, 3,973 wild boars were marked (1,954 males and 2,019 females), among them 2,548 individuals (1,258
males and 1,290 females), i.e. 64%, were recovered after being shot by hunters (n = 2,486) or killed by car collision (n = 62). About 17.5% of males and 18.3% of females that were marked as young were never recorded after the first capture event and were thus excluded from the analyses: those individuals could have died from natural causes (e.g. disease) or other mortality causes (hunting, car collision, etc.).

## (b) Restricted dataset to study natal dispersal

To study natal dispersal, individuals should have been caught and marked young enough prior to their natal dispersal, and then recovered dead old enough after dispersal. In wild boar, males begin to disperse at the age of 10 months, and dispersal ceases at the age of 16 months, while females begin to disperse at 7 months and dispersal ceases at the age of 11 months (Truvé and Lemel 2003). Therefore, we restricted our analyses of natal dispersal to individuals younger than 7 months of age at first capture, and dead at 16 months of age or older.

The age of the individuals at capture (in days) corresponds to body mass at capture (in kg) minus the birth mass, divided by the growth rate (in kg.d⁻¹), assuming birth mass equals 1 kg (Gamelon et al. 2011) and individual growth rate is linear over the first months of life (Gaillard et al. 1992, Veylit et al. 2020a). Previous work has shown that body growth rate can strongly vary among populations (Veylit et al. 2020b). Therefore, we estimated body growth rate early in life for a subset of individuals weighing less than 20 kg at capture and shot below 50 kg, and ensured that a maximum of 150 days elapsed between the capture and the death events (sample size = 264 individuals). We assumed a linear body growth rate between capture and death (see Gaillard et al. 1992, Veylit et al. 2020a for a full justification). We then tested whether the body growth rate was sex-specific, using a linear regression with individual body growth rate as a response variable and sex as a categorical effect. This model was compared to the null model using a Likelihood Ratio Test (LRT), which compares the
difference in deviance between the two nested models. The estimate of body growth rate was retrieved from the selected model.

Once the mean body growth rate was estimated, the age of all individuals weighing less than 20 kg at first capture (i.e. small enough for estimating accurately their age) was estimated, and individuals younger than 7 months of age at first capture, and shot at 16 months of age or older were kept (sample size = 836 out of the initial 2,486 individuals, 20 died from car collisions and all others by hunting). The analysis of natal dispersal was thus restricted to this final dataset containing 836 individuals (404 males and 432 females). The median age at death was estimated to be 1.69 years for males and 1.79 years for females. As a check, we back-calculated the birth dates of all individuals for a visual inspection of their distribution.
As the rut usually begins in mid-December (Cachelou et al. 2022) and the gestation length is 115 days, a birth peak was expected around April-June, which matched with observed data (Appendix S1, Figure S2).

### (c) Estimating dispersal metrics

We first calculated the Euclidean distance (in m) between the trap where a given individual was captured and the place where it was shot. We added 1 to the distance and log-transformed it. This corresponds to the log-transformed dispersal distance. To determine the propensity to disperse, we defined a threshold value beyond which a given individual is considered as having dispersed, and below which it is considered as philopatric (see Gaillard et al. 2008, Vanpé et al. 2015 for similar approaches). This sex-specific threshold value corresponds to the diameter of an average home range for wild boar, i.e. 3,190 m for males and 2,250 m for females (corresponding to a home range of 800 ha for males and 400 ha for females, Mauget 1980, Fattebert et al. 2017). Dispersal propensity thus corresponds to a dichotomous categorical variable (i.e. 1 when natal dispersal occurs and 0 otherwise), and should be interpreted relatively to the threshold value considered.
189 (d) Statistical analyses

190 To test our prediction that natal dispersal patterns should be sex dependent (P1), we used a
191 linear-mixed model with dispersal distance (log-transformed) as a response variable, sex as a
192 fixed categorical effect, and year as a random factor, and we compared this model to a null
193 model using a LRT. Similarly, we used a generalized linear-mixed model with dispersal
194 propensity as the response variable, sex as a fixed categorical effect, and year as a random factor
195 using a binomial link function, and we compared this model to a null model using a LRT.
196 Because males and females displayed contrasting patterns in terms of both dispersal distance
197 and dispersal propensity (see results), repeatability analyses were performed on males and
198 females separately.

199 To assess the influence of social group on natal dispersal distances within a family (P2), we
200 first assigned individuals to a family. Poteaux et al. (2009) found that young wild boars captured
201 in the same trap the same day were genetically highly related, so we defined a family as the set
202 of individuals captured in the same trap the same day. We estimated the sex-specific median
203 dispersal distance per family, added 1 to the median distance and log-transformed it. We
204 excluded the families containing only one individual, one sex only, or for which one of the
205 sexes had a median dispersal distance of zero (no dispersal at all), as it would be meaningless
206 to estimate sex-specific median dispersal distance in those specific cases. Then, we used a
207 linear-mixed model with the median dispersal distance of males as a response variable, the
208 median dispersal distance of females as a covariate, and year as a random factor (sample size =
209 272 individuals, corresponding to 96 families), and assessed whether dispersal distance of
210 females and males were positively related.

211 To assess the influence of social group on sex-specific natal dispersal patterns (P3), we assigned
212 individuals to a family, but here we restricted our definition of a family as the set of individuals
213 of the same sex (because the analysis is sex-specific) captured in the same trap the same day.
Then, for males and females separately, we used a linear-mixed model with individual dispersal distance (log-transformed) as a response variable and family and location of the trap as random factors. Adding "location of the trap" in the analyses allowed us to estimate the repeatability not only at the level of the family but also at the level of the location group, and thus to disentangle the social effects from the spatial effects. We calculated the repeatability (Nakagawa and Schielzeth 2010) of dispersal distance in a given family and in a given trap for families with more than one individual because estimating repeatability for one individual would be meaningless (sample size for females = 144, belonging to 63 families and 18 traps; sample size for males = 141, belonging to 61 families and 17 traps). Repeatability corresponds to the proportion of the total variance (in dispersal distance in our case) accounted for by differences among groups (families or trap location here). To evaluate the uncertainty of the repeatability estimates, the number of parametric bootstraps was set to 1,000 and 95% confidence intervals were computed. Statistical significance was assessed by a LRT and 1,000 permutation tests. Analyses of repeatability were performed using the package rptR (Stoffel et al. 2017). We replicated the exact same analysis on a subset of individuals that have dispersed (propensity=1), thus excluding philopatric individuals, resulting in 81 males and 54 females. Finally, instead of considering dispersal distance as the response variable, we used propensity and a binomial link function to assess the repeatability of dispersal propensity within a given family and a given trap.

All the analyses were performed in R ver. 4.3.2 (www.r-project.org) and the dataset is provided in Gamelon (2025).

235

## 236 Results

As expected based on previous studies, we found no evidence for sex-specific individual body growth rate in early life (LRT: $\chi^2$= 2.632, df=1, p=0.105). Body growth rate was estimated to

237

238
239 be 0.143 kg.d⁻¹ (SE: 0.004) (n = 264 individuals). This rate was used to estimate individual
240 ages of both males and females.

241 As expected, we found strong evidence for sex-specific natal dispersal patterns. For the
242 dispersal distance, the model including sex outperformed the null model (LRT: χ²=54.465,
243 df=1, p<0.001) (n = 404 males and 432 females). Males had longer dispersal distance than
244 females (sex effect: 1.408 (SE: 0.188)) with a mean dispersal distance twice as large in males
245 than in females (10.071 km (SD: 18.289 km) vs. 5.070 km (SD=12.816 km), respectively).
246 Interestingly, the range of dispersal distance was larger in females (from 0 to 161.940 km,
247 Figure 1B) than in males (from 0 to 144.366 km, Figure 1A), leading to a higher individual
248 heterogeneity in dispersal distance of females than males (coefficient of variation of 2.53 vs.
249 1.82, respectively). For the propensity to disperse, again as expected from P1, the model
250 including sex was better supported than the null model (LRT: χ²= 25.385, df=1, p<0.001).
251 Males had higher propensity to disperse than females (sex effect: 0.714 (SE: 0.143)), with a
252 mean dispersal propensity of 55.9% vs. 38.4% for females. These findings strongly support
253 our first prediction.

254 To assess the influence of social group on natal dispersal distances, individuals were assigned
255 to a family. A total of 51 families were of size 2, 26 of size 3, 11 of size 4, 4 of size 5, 1 of
256 size 6, 2 of size 7, and 1 of size 8. We found some evidence for a positive relationship
257 between median dispersal distance (log-transformed) of offspring males and females within a
258 social group (slope of the relationship between male and female dispersal distances = 0.199,
259 SE=0.113, p=0.083), indicating that families with females dispersing farther tend to be the
260 ones where males dispersed the farthest too (Appendix S1, Figure S3). These findings are in
261 line with our second prediction.

262 To assess the influence of social group on sex-specific natal dispersal patterns, individuals
263 were assigned to a family. For males, 46 families were of size 2, 13 of size 3 and 2 of size 5.
For females, family sizes varied between 2 and 4, with 50, 8 and 5 families of size 2, 3 and 4, respectively. Male dispersal distance (log-transformed) was not repeatable within a family (mean repeatability of 0.09, Appendix S1, Table S1), whereas female dispersal distance was repeatable within a family (mean repeatability of 0.354, Appendix S1, Table S1). On the other hand, we did not find any evidence of repeatability of dispersal distance within a trap location for either males or females (mean repeatability of 0 and 0.031, respectively, Appendix S1, Table S1). The propensity to disperse was not repeatable for males within a family (mean repeatability of 0, Appendix S1, Table S1), whereas for females, it was repeatable (mean repeatability of 0.265 on the original scale and of 0.310 on the link scale, Appendix S1, Table S1). Like for dispersal distance, we did not find any evidence of repeatability of dispersal propensity within a trap location for either males or females (mean repeatability of 0 and 0.116, respectively, Appendix S1, Table S1). These findings provide mixed support for our third and fourth predictions and show a complex interplay among sex, NHPI, and components of the dispersal process.

When the analysis was replicated on the subset of individuals having dispersed (i.e. propensity of 1), we found again that female dispersal distance was repeatable within a family (mean repeatability of 0.397, Appendix S1, Table S1). The repeatability of male dispersal distance increased to 0.323, a value close to that observed in females.

## Discussion

While natal dispersal has been intensively studied, the role played by family effects in a large social mammal in relation to offspring sex has remained an open question. We found clear support for two predictions (P1 and P3a), and partial support for others (P2, P3b).

*Sex-biased dispersal, consequences for the most philopatric sex, and evidence for individual heterogeneity (P1)*
Looking at the broad picture of dispersal patterns at the population level, in accordance with both theoretical expectations and previous empirical evidence accumulated in large mammals (Truvé and Lemel 2003, Podgórski et al. 2014, Brom et al. 2016), we found that offspring males disperse more often and farther on average than offspring females. Most males in the dataset died at young ages (median: 1.69 years), but some of them reached old ages (maximum age recorded: 8.78 years) meaning that some breeding dispersal during adulthood cannot be excluded. Philopatry, i.e. remaining in the natal area with kin, for the sex exhibiting a low natal dispersal contributes to form groups of related individuals, with several advantages. This may enhance some reproductive share within the group, as shown in a cooperative breeding fish (Hellmann et al. 2015) or in the well-studied meerkat (Clutton-Brock et al. 1999). As in other social species, communal rearing of offspring, the so-called “piglet-sitting”, may favor wild boar females’ reproductive success and in turn increase their inclusive fitness (Focardi et al. 2015). Similarly, staying with kin can increase foraging efficiency, reduce predation risk, and improve survival (Focardi et al. 2015, Jungwirth et al. 2023) through cooperation with relatives. Noticeably, a sex described as philopatric can hide important among-individual heterogeneity in dispersal patterns. Even though wild boar females have lower propensity and lower dispersal distances than males on average, they display a high heterogeneity in dispersal distances, with a coefficient of variation larger than that of males. The longest dispersal distance observed in this long-term study has even been recorded for a female (Figure 1B).

*Strength of similarities of dispersal patterns among offspring within a group (P2, P3)*

Looking more specifically at similarities of dispersal patterns among relatives, most of the studies published have so far focused on birds, lizards and small mammals (see Massot and Clobert 2000 for a review). In wild boar, we found some evidence for a positive relationship between dispersal distances of offspring males and females born within the same social group
313 (P2), so that families with females dispersing farther tend to be the ones where males
dispersed the farthest too. Within a family, while females tend to behave similarly when
314 facing the following questions: "*should I stay or should I go?*" and "*if I go, how far should it
315 be?*" (P3a), for males, both the propensity to disperse and the dispersal distance were poorly
316 repeatable, highlighting a high within-group diversity of dispersal patterns among related
317 males (P3b). This is likely due to the matriarchal organization in wild boar, with most of the
318 females from a family staying at the same location (philopatry), or most of them dispersing in
319 parallel, allowing familiar relationships to be maintained (see some case studies of parallel
dispersal in Lawson Handley and Perrin 2007). For male dispersers (i.e. with a dispersal
320 propensity of 1), however, repeatability of dispersal distance within a family was as high as in
321 females. These findings raise the questions of the underlying mechanisms causing similarities
322 of dispersal patterns among offspring within a same family.
323

325 Several mechanisms can explain similarities of dispersal patterns among offspring within a
326 family. For instance, in common lizards, mothers in good condition displaying low pre-natal
327 maternal corticosterone, which is the predominant stress hormone in vertebrates, produce
328 offspring with a high propensity to disperse, whereas mothers with opposite characteristics
329 tend to produce more philopatric offspring (De Fraipont et al. 2000). Such maternal effects
330 can explain strong family effects in dispersal patterns among offspring from the same social
331 group. Similarly, the occurrence of a NHPI (Davis and Stamps 2004) may generate
332 similarities in dispersal patterns among offspring from the same family, when individuals
333 disperse towards areas similar to their natal habitat. Therefore, a complex interplay among
334 behavioral, physiological, and genetic mechanisms, which are not mutually exclusive, can
335 induce family effects on dispersal patterns.
336

Conclusions
To what extent the results we obtained in this wild boar population can be generalized to other populations with contrasting ecological contexts (e.g. contrasting landscape resistances or different harvesting strategies that may affect family structure) remains to be carefully assessed. While individual attributes such as body condition or sex have been identified as the main structuring factors of dispersal patterns in vertebrates (see Li and Kokko 2019 for sex-biased dispersal, for condition-dependent dispersal Bonte and De La Peña 2009), family effects have remained surprisingly overlooked. Our findings demonstrate that family effects also structure natal dispersal patterns in a sex-specific way in the social wild boar species. We thereby anticipate that family effects matter and have to be accounted for when studying dispersal in social species. In particular, future studies should decipher how family effects interplay with condition-dependence to shape dispersal patterns in social species. Assessing the magnitude of resemblance in dispersal patterns among kin in social species, and investigating how similarities among kin vary along the sociality continuum across species (Salguero-Gómez 2024) is likely to improve our understanding of the natal dispersal process.

**Acknowledgments.** We warmly thank Petter Kjellander, Burt Kotler and one anonymous referee for insightful comments on an earlier version of this work. We thank all the persons from the military camp of Fontevraud-l'Abbaye, France, for running the long-term monitoring of the wild boar population. This work was funded by the French National Research Agency ANR PURE project to MG (ANR-23-CE02-0028).

**Author contribution.** MG and JMG conceived the study. JPC and colleagues collected the data. AG curated the data, AG and MG ran the analyses. MG and JMG wrote the first draft of the manuscript. All authors provided comments on the paper and agreed on the final version.

**Conflict of interest statement.** We declare we have no conflict of interests.
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Figure 1. Frequency distribution of natal dispersal distances (i.e. linear distances (in meters)) between the location of the trap and the location of the death by shooting or car collision) for A) 404 wild boar males and B) 432 wild boar females. The vertical red lines indicate the threshold value beyond which individuals are considered to have dispersed, and below which they are assigned to be philopatric. This sex-specific threshold distance corresponds to 3,190 m for males and 2,250 m for females.

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